Journal articles: 'Tridentate Ligands - Metal Complexes'

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Alghamdi, Israa A., Mohamed Abdelbaset, and Ines El Mannoubi. "Mixed Ligand Complexes of Copper(II) and Cobalt(II) with Hydrazones Derivatives and ortho-Vanillin: Syntheses, Characterizations and Antimicrobial Activity." Oriental Journal of Chemistry 35, no. 6 (December 30, 2019): 1722–30. http://dx.doi.org/10.13005/ojc/350614.

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The purpose of this paper was to synthesis new mixed-ligand Cu(II) and Co(II) metal complexes utilizing bidentate and tridentate donor hydrazones derivatives as primary ligands and o-vanillin as co-ligand. The obtained compounds were characterized by elemental analysis, Infrared, UV-Vis., 1H-NMR, Mass spectra, molar conductance, thermal analysis and atomic absorption spectroscopy (ASS). Spectroscopic analysis results indicated that the hydrazone ligand (L1) behave as tridentate (ONO) and forms metal complexes having distorted square planar geometry. While the ligands (L2, L3 AND L4) behave as bidentate (NO) and forms metal complexes having octahedral geometry around the central metal atoms. The antimicrobial potentials were assessed for the ligand (L2) and its metal complexes only and were screened against six types of bacterial strains and one fungal strain. The antimicrobial activities results of the tested compounds showed enhanced activity of the complexes over their parent ligands.

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Hanan, Garry S., Dirk Volkmer, and Jean-Marie Lehn. "Coordination arrays Synthesis and characterization of tetranuclear complexes of grid-type." Canadian Journal of Chemistry 82, no. 10 (October 1, 2004): 1428–34. http://dx.doi.org/10.1139/v04-092.

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A series of tetranuclear metal complexes of grid-type consisting of four bis-tridentate ligands and four divalent transition metal ions were synthesized and characterized. The 1H NMR spectra of diamagnetic complexes containing Zn(II), Cd(II), Fe(II), and Ru(II) was correlated to the radius of the metal ion. The UVvis and electrochemical results indicated that the bridging ligand π* orbital and the dπ metal orbital are stabilized by complexation of more than one metal ion. Furthermore, the Co(II) and Fe(II) grids exhibit metalmetal interaction mediated by the bis-tridentate ligands as indicated by electrochemical and spectroscopic methods. These results provide guidelines for the design of larger grids bearing several metal centres in a square arrangement, which also represent potential components of molecular electronic devices.Key words: complexes with nitrogen ligands, octahedral metal ions, self-assembly, supramolecular chemistry.

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Polo-Cerón, Dorian. "Cu(II) and Ni(II) Complexes with New Tridentate NNS Thiosemicarbazones: Synthesis, Characterisation, DNA Interaction, and Antibacterial Activity." Bioinorganic Chemistry and Applications 2019 (July 1, 2019): 1–14. http://dx.doi.org/10.1155/2019/3520837.

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This paper reports the synthesis and detailed characterisation of copper(II) and nickel(II) complexes with tridentate thiosemicarbazone ligands H2L1 and H2L2 derived from 2-acetylpyrazine. The ligands and their metal complexes were characterised by different physicochemical techniques, including elemental and thermogravimetric analysis; UV-Vis, IR, 1H-NMR, and 13C-NMR spectroscopy; molar conductance measurements; and mass spectrometry. The crystal structure of the H2L1 ligand was determined by single crystal X-ray diffraction studies. The spectral data showed that the thiosemicarbazone behaves as an NNS tridentate ligand through the nitrogen atoms of the azomethine group and pyrazine ring and the sulphur atom of the thioamide group. Elemental and thermal analyses indicated that the obtained metal complexes had a 1 : 1 stoichiometry (metal-ligand). The interactions between these complexes and calf thymus DNA (CT-DNA) were studied by electronic absorption and viscosity measurements. The activities of these compounds against oxidative DNA cleavage were examined by agarose gel electrophoresis. Cu(II) and Ni(II) complexes can wind DNA strands through groove interactions and promote strand breakage of the plasmid pmCherry under oxidative stress conditions. Moreover, all the complexes could interact more strongly with DNA than could with the free ligands. Finally, the antibacterial activities of the ligands and their complexes were determined by in vitro tests against Gram-positive bacterial strains (S. aureus ATCC 25923, L. monocytogenes ATCC 19115, and B. cereus ATCC 10876) and Gram-negative bacterial strains (E. coli ATCC 25922, S. typhimurium ATCC 14028, and K. pneumoniae ATCC BAA-2146) using the broth microdilution method. The metal complexes showed greater antimicrobial activities than the precursor ligands against some of the microorganisms.

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Chan, Chung Ying, and Peter J. Barnard. "Rhenium complexes of bidentate, bis-bidentate and tridentate N-heterocyclic carbene ligands." Dalton Transactions 44, no. 44 (2015): 19126–40. http://dx.doi.org/10.1039/c5dt03295d.

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Rhenium(i) tricarbonyl complexes of a range of bidentate, bis-bidentate and tridentate NHC ligands have been prepared. These NHC ligands are of interest for possible applications in the development of Tc-99m or Re-186/188 radiopharmaceuticals and the stability of two complexes were evaluated in ligand challenge experiments using the metal binding amino acids l-histidine or l-cysteine.

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Jamil, Yasmin Mos'ad, Fathi Mohammed Al-Azab, and Nedhal Abdulmawla Al-Selwi. "Novel organophosphorus Schiff base ligands: Synthesis, characterization, ligational aspects, XRD and biological activity studies." Ecletica Quimica 48, no. 3 (July 1, 2023): 36–53. http://dx.doi.org/10.26850/1678-4618eqj.v48.3.2023.p36-53.

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Six complexes have been synthesized from Cu(II), Ni(II), and Co(II) with new bidentate N2 donor Schiff base ligand (2-methoxybenzalidene-1-phenylsemicarbazide L1) and tridentate N2O donor organophosphorus Schiff base ligand (2-methoxybenzalidenediphenylphosphate-1-phenylsemicarbazide L2). Both ligands were synthesized and characterized by metal analysis, infrared (IR), ultraviolet visible (UV-Vis), and nuclear magnetic resonance (NMR) spectral studies. The chemical structures of the synthesized complexes were characterized using their metal analysis, magnetic susceptibility, molar conductance, IR, and UV-Vis spectra. According to molar ratio studies, the complexes have the composition of ML2 for L1 and ML for L2. The X-ray diffraction (XRD) studies showed that the particle size of ligands and L1 complexes were in nano-range. The ligands and their metal complexes have been screened for their antioxidant, antibacterial and antifungal activity.

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Laramée-Milette, Baptiste, and Garry S. Hanan. "Ruthenium bistridentate complexes with non-symmetrical hexahydro-pyrimidopyrimidine ligands: a structural and theoretical investigation of their optical and electrochemical properties." Dalton Transactions 45, no. 31 (2016): 12507–17. http://dx.doi.org/10.1039/c6dt02408d.

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The optical and electronic properties of six Ru complexes with non-symmetrical tridentate ligands have been investigated and, as corroborated by electrochemical data, the presence of the hpp ligand strongly affects the oxidation potential of the metal ion.

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Kavitha, Palakuri, and K. Laxma Reddy. "Synthesis, Structural Characterization, and Biological Activity Studies of Ni(II) and Zn(II) Complexes." Bioinorganic Chemistry and Applications 2014 (2014): 1–13. http://dx.doi.org/10.1155/2014/568741.

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Ni(II) and Zn(II) complexes were synthesized from tridentate 3-formyl chromone Schiff bases such as 3-((2-hydroxyphenylimino)methyl)-4H-chromen-4-one (HL1), 2-((4-oxo-4H-chromen-3-yl)methylneamino)benzoic acid (HL2), 3-((3-hydroxypyridin-2-ylimino)methyl)-4H-chromen-4-one (HL3), and 3-((2-mercaptophenylimino)methyl)-4H-chromen-4-one (HL4). All the complexes were characterized in the light of elemental analysis, molar conductance, FTIR, UV-VIS, magnetic, thermal, powder XRD, and SEM studies. The conductance and spectroscopic data suggested that, the ligands act as neutral and monobasic tridentate ligands and form octahedral complexes with general formula [M(L1–4)2]·nH2O (M = Ni(II) and Zn(II)). Metal complexes exhibited pronounced activity against tested bacteria and fungi strains compared to the ligands. In addition metal complexes displayed good antioxidant and moderate nematicidal activities. The cytotoxicity of ligands and their metal complexes have been evaluated by MTT assay. The DNA cleavage activity of the metal complexes was performed using agarose gel electrophoresis in the presence and absence of oxidant H2O2. All metal complexes showed significant nuclease activity in the presence of H2O2.

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Peng, Deqian, Xinwen Yan, Chao Yu, Shaowen Zhang, and Xiaofang Li. "Transition metal complexes bearing tridentate ligands for precise olefin polymerization." Polymer Chemistry 7, no. 15 (2016): 2601–34. http://dx.doi.org/10.1039/c6py00040a.

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Aragón-Muriel, Alberto, Viviana Reyes-Márquez, Farrah Cañavera-Buelvas, Jesús R. Parra-Unda, Fernando Cuenú-Cabezas, Dorian Polo-Cerón, Raúl Colorado-Peralta, Galdina V. Suárez-Moreno, Bethsy Adriana Aguilar-Castillo, and David Morales-Morales. "Pincer Complexes Derived from Tridentate Schiff Bases for Their Use as Antimicrobial Metallopharmaceuticals." Inorganics 10, no. 9 (September 5, 2022): 134. http://dx.doi.org/10.3390/inorganics10090134.

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Within the current challenges in medicinal chemistry, the development of new and better therapeutic agents effective against infectious diseases produced by bacteria, fungi, viruses, and parasites stands out. With chemotherapy as one of the main strategies against these diseases focusing on the administration of organic and inorganic drugs, the latter is generally based on the synergistic effect produced by the formation of metal complexes with biologically active organic compounds. In this sense, Schiff bases (SBs) represent and ideal ligand scaffold since they have demonstrated a broad spectrum of antitumor, antiviral, antimicrobial, and anti-inflammatory activities, among others. In addition, SBs are synthesized in an easy manner from one-step condensation reactions, being thus suitable for facile structural modifications, having the imine group as a coordination point found in most of their metal complexes, and promoting chelation when other donor atoms are three, four, or five bonds apart. However, despite the wide variety of metal complexes found in the literature using this type of ligands, only a handful of them include on their structures tridentate SBs ligands and their biological evaluation has been explored. Hence, this review summarizes the most important antimicrobial activity results reported this far for pincer-type complexes (main group and d-block) derived from SBs tridentate ligands.

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Sumby, Christopher J., Ben A. Leita, Boujemaa Moubaraki, Keith S. Murray, and Peter J. Steel. "Synthesis and Coordination Chemistry of Doubly-Tridentate Tripodal Pyridazine and Pyrimidine-Derived Ligands: Structural Interplay Between M2L and M2L2 (M = Ni and Pd) Complexes and Magnetic Properties of Iron(II) Complexes." Australian Journal of Chemistry 62, no. 9 (2009): 1142. http://dx.doi.org/10.1071/ch09244.

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The coordination chemistry of three bridging doubly-tridentate ligands, including the known compound 3,6-bis(di-2-pyridylmethyl)pyridazine (1), which is structurally similar to 1,4-bis(di-2-pyridylmethyl)phthalazine (2), and two pyrimidine-linked compounds 4,6-bis(di-2-pyridylmethyl)pyrimidine (3), and 4,6-bis(di-2-pyridylamino)pyrimidine (4), was investigated with FeII, NiII, and PdII metal salts. Ligands 3 and 4 were synthesized in one-pot reactions from easily obtained starting materials; compound 3 was synthesized from di-2-pyridylmethane and 4,6-diiodopyrimidine in 48% yield, while ligand 4 was prepared by reacting di-2-pyridylamine with 4,6-dichloropyrimidine in 27% yield. During the synthesis of 4, an additional compound, 4-chloro-6-(di-2-pyridylamino)pyrimidine (5), with only one tridentate binding site was obtained in 30% yield. Reactions of 1, 3, and 4 with FeII or NiII salts gave two types of complexes, either discrete M2L or M2L2 assemblies. The PdII complexes obtained were also characterized as discrete M2L complexes. The compounds were characterized by a combination of NMR and IR spectroscopy, microanalysis and X-ray crystallography. Noticeable differences in the structures obtained for NiII coordination complexes with the carbon-linked (3) and nitrogen-linked (4) ligands were observed, whereby the nitrogen linker adopted a trigonal planar geometry and prevented tridentate facial coordination of the octahedral metal centres. The magnetic properties of dinuclear FeII complexes of 1 were examined to see if they showed spin-crossover effects, a feature recently observed by others in other dinuclear helicate complexes, but the complexes remained high-spin at all temperatures between 300 and 2 K.

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Mekala, Himabindu, Rambabu Palabindela, Prabhakar Myadaraveni, Devendar Banothu, Gangalla Ravi, and Mamatha Kasula. "MOLECULAR DOCKING INVESTIGATIONS OF THIOSEMICARBAZONE Cu(II) and Zn(II) METAL COMPLEXES AGAINST EGFR, HER2, AND IKK-β TARGET PROTEINS: SYNTHESIS, CHARACTERIZATION AND BIOLOGICAL SCREENING." RASAYAN Journal of Chemistry 16, no. 03 (2023): 1309–18. http://dx.doi.org/10.31788/rjc.2023.1636895.

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Cu(II) and Zn(II) complexes of Schiff bases produced from thiosemicarbazone with Anthracene, indole, pyrimidines, and chromones have been synthesized and physiochemically characterized. Among the synthesized ligands L1-L4, the first three ligands behave as uninegative bidentate ones towards Cu(II) and Zn(II) metals, whereas the L4 ligand behaves as a uninegative tridentate one. The structure and bonding properties of the complexes have been investigated using electronic and HRMS-spectral data. All the ligands and complexes were tested for their anti-cancer and anti-bacterial activities. Docking studies demonstrated that Cu(II) and Zn(II) complexes interacted favorably with the EGFR, HER2, and IKK-β receptors.

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Fürmeyer, Fabian, Danny Münzberg, Luca M. Carrella, and Eva Rentschler. "First Cobalt(II) Spin Crossover Compound with N4S2-Donorset." Molecules 25, no. 4 (February 14, 2020): 855. http://dx.doi.org/10.3390/molecules25040855.

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Herein we report the synthesis and characterization of a novel bis-tridentate 1,3,4-thiadiazole ligand (L = 2,5-bis[(2-pyridylmethyl)thio]methyl-1,3,4-thiadiazole). Two new mononuclear complexes of the type [MII(L)2](ClO4)2 (with M = FeII (C1) and CoII (C2)) have been synthesized, containing the new ligand (L). In both complexes the metal centers are coordinated by an N4S2-donorset and each of the two ligands is donating to the metal ion with just one of the tridentate pockets. The iron(II) complex (C1) is in the low spin [LS] state below room temperature and shows an increase in the magnetic moment only above 300 K. In contrast, the cobalt(II) complex (C2) shows a gradual spin crossover (SCO) with T1/2 = 175 K. To our knowledge, this is the first cobalt(II) SCO complex with an N4S2-coordination.

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Pajoudoro, Djafarou Ngouh, Daniel Lissouck, Baruch Ateba Amana, Joseph Zobo Mfomo, A. E. B. Abdallah, Alfred Aristide Flavien Toze, and Désiré Bikele Mama. "Antioxidant Properties of Lapachol and Its Derivatives and Their Ability to Chelate Iron (II) Cation: DFT and QTAIM Studies." Bioinorganic Chemistry and Applications 2020 (March 31, 2020): 1–10. http://dx.doi.org/10.1155/2020/2103239.

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The elucidation of the complexation of lapachol and its derivatives to Fe2+ cation has been done using the density functional theory (DFT). This complexation has been limited to bidentate and tridentate to Fe2+ cation. Geometry optimizations have been implemented in gas and solution phase (water, acetonitrile, chlorobenzene, benzene, and toluene) for ligands at B3LYP/6-311++G (d,p) level of theory using B3LYP/6-31+G(d,p) optimized data as starting point. But, the geometrical optimizations in solution phase of the 22 complexes analyzed of lapachol and its derivatives to Fe2+ cation were restricted to acetonitrile and benzene. The complexation energy and the metal ion affinity (MIA) have also been calculated using the B3LYP method. The results obtained indicated a proportionality between the MIA values and the retained charge on Fe2+ cation for k2-(O1,O2) modes. But, an inverse proportionality has been yielded between these two parameters for k3-(O2, C=C) tridentate modes. For k3-(O3,C=C) tridentate mode coordination, the higher stability has been obtained. In this latter tridentate coordination in gas phase, the topological analysis of complexes exhibits the fact that the electron density is concentrated between the O3 oxygen atom of the ligand attached to Fe2+ and this metal cation. Moreover, the hydrogen bond strength calculated for isolated ligands (situated between 23.92 and 30.15 kJ/mol) is in the range of normal HBs. Collectively, all the complexation processes have shown to be highly exothermic. Our results have also shown that the electron extraction from Fe2+...Lai complexes is more difficult compared to that from free ligands.

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Morales-Espinosa, Eric G., Naytze Ortiz-Pastrana, Valente Gómez-Benítez, Reyna Reyes-Martínez, Hilda Amelia Piñón-Castillo, Laura A. Manjarrez-Nevárez, Juan M. German-Acacio, and David Morales-Morales. "Synthesis and Characterization of Two Isostructural POCOP Ni(II) Pincer Complexes Containing Fluorothiophenolate Ligands: [Ni(SC6F4-4-H){C6H2-3-(C2H3O)-2,6-(OPiPr2)2}] and [Ni(SC6F5){C6H2-3-(C2H3O)-2,6-(OPiPr2)2}]." Molbank 2022, no. 2 (May 9, 2022): M1359. http://dx.doi.org/10.3390/m1359.

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Among their many applications, metal pincer complexes are of interest for their properties as catalysts in cross-coupling reactions. Pincer ligands exhibit tridentate coordination to the metal center and occupy the meridional positions forming two chelate rings. The two Ni(II) POCOP pincer complexes with a fluorothiophenolate ligand reported herein, with formulas [Ni(SC6F4-4-H){C6H2-3-(C2H3O)-2,6-(OPiPr2)2}] (2) and [Ni(SC6F5){C6H2-3-(C2H3O)-2,6-(OPiPr2)2}] (3), are isostructural. Additionally, they are prepared in a facile manner from the chloride compound [NiCl{C6H2-3-(C2H3O)-2-6-(OPiPr2)2}] (1). The complexes exhibited slightly distorted square planar geometries around the metal. The fluorothiophenolate ligands are responsible of the C—H···F, C—F···π and C=O···πF interactions that contribute to stabilize the crystal structure arrays.

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Bartholomew, Amymarie K., Louise M. Guard, Nilay Hazari, and Eddie D. Luzik. "Synthesis of Mg Complexes Supported by Tris-(1-pyrazolyl)phosphine." Australian Journal of Chemistry 66, no. 11 (2013): 1455. http://dx.doi.org/10.1071/ch13354.

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The preparation and characterisation of two Mg coordination compounds supported by the tris(1-pyrazolyl)phosphine (P(pz)3) ligand, [{P(pz)3}Mg(MeCN)3](I)2 and [Mg{P(pz)3}2](I)2, is described. This is the first time this ligand has been coordinated to Mg or any other s-block metal and the complexes are the first examples of crystallographically characterised P(pz)3 complexes on any metal. The structures of the new Mg complexes are compared with related species with the more common tridentate facial ligands, tris(pyrazolyl)hydroborate (Tp), tris(pyrazolyl)methane (Tpm), and tris(pyrazolyl)methanide (Tpmd).

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Suresh, Lakshmi, Ralte Lalrempuia, Jonas B. Ekeli, Francis Gillis-D’Hamers, Karl W. Törnroos, Vidar R. Jensen, and Erwan Le Roux. "Unsaturated and Benzannulated N-Heterocyclic Carbene Complexes of Titanium and Hafnium: Impact on Catalysts Structure and Performance in Copolymerization of Cyclohexene Oxide with CO2." Molecules 25, no. 19 (September 23, 2020): 4364. http://dx.doi.org/10.3390/molecules25194364.

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Tridentate, bis-phenolate N-heterocyclic carbenes (NHCs) are among the ligands giving the most selective and active group 4-based catalysts for the copolymerization of cyclohexene oxide (CHO) with CO2. In particular, ligands based on imidazolidin-2-ylidene (saturated NHC) moieties have given catalysts which exclusively form polycarbonate in moderate-to-high yields even under low CO2 pressure and at low copolymerization temperatures. Here, to evaluate the influence of the NHC moiety on the molecular structure of the catalyst and its performance in copolymerization, we extend this chemistry by synthesizing and characterizing titanium complexes bearing tridentate bis-phenolate imidazol-2-ylidene (unsaturated NHC) and benzimidazol-2-ylidene (benzannulated NHC) ligands. The electronic properties of the ligands and the nature of their bonds to titanium are studied using density functional theory (DFT) and natural bond orbital (NBO) analysis. The metal–NHC bond distances and bond strengths are governed by ligand-to-metal σ- and π-donation, whereas back-donation directly from the metal to the NHC ligand seems to be less important. The NHC π-acceptor orbitals are still involved in bonding, as they interact with THF and isopropoxide oxygen lone-pair donor orbitals. The new complexes are, when combined with [PPN]Cl co-catalyst, selective in polycarbonate formation. The highest activity, albeit lower than that of the previously reported Ti catalysts based on saturated NHC, was obtained with the benzannulated NHC-Ti catalyst. Attempts to synthesize unsaturated and benzannulated NHC analogues based on Hf invariably led, as in earlier work with Zr, to a mixture of products that include zwitterionic and homoleptic complexes. However, the benzannulated NHC-Hf complexes were obtained as the major products, allowing for isolation. Although these complexes selectively form polycarbonate, their catalytic performance is inferior to that of analogues based on saturated NHC.

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S. Sharma, S., J. V. Ramani, D. P. Dalwadi, J. J. Bhalodia, N. K. Patel, D. D. Patel, and R. K. Patel. "New Ternary Transition Metal Complexes of 2-{[(2-aminophenyl)imino] methyl}Phenol and Metformin: Synthesis, Characterization and Antimicrobial Activity." E-Journal of Chemistry 8, no. 1 (2011): 361–67. http://dx.doi.org/10.1155/2011/723491.

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Complexes of Co(II), Ni(II) and Cu(II) were synthesized from Schiff base 2-{[(2-aminophenyl)imino]methyl}phenol and metformin. The authenticity of the transition metal complexes were characterized by elemental analyses, conductance and magnetic susceptibility measurements, as well as spectroscopic (IR, electronic) and thermal studies. IR spectral studies revealed the existence of the ligands in the amine form in the solid state. The magnetic and electronic spectral studies suggest an octahedral geometry for all the complexes. The metformin acts as a bidentate ligand and Schiff base ofo-phynelendiamine and salicylaldehyde acts as a tridentate ligand. Antimicrobial screening of the Schiff base, metformin and transition metal complexes were determined against the bacteriaEscherichia coliandBacillus megaterium.

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Jayarajan, Ramasamy, Gnanasambandam Vasuki, and Pillutla Sambasiva Rao. "Synthesis and Antimicrobial Studies of Tridentate Schiff Base Ligands with Pyrazolone Moiety and Their Metal Complexes." Organic Chemistry International 2010 (December 26, 2010): 1–7. http://dx.doi.org/10.1155/2010/648589.

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Synthesis, characterization, and antimicrobial activity of tridentate Schiffbase ligands containing pyrazolone moiety (3a and 3b) and their transition metal complexes of VO(II), Cu(II), Fe(III), and Co(II) 4a–h have been investigated. The complexes show enhanced antibacterial activity against S. aureus, E. coli, and S. typhi and antifungal activity against C. albicans, Rhizopus sp., and A. niger compared to the ligands.

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Journal, Baghdad Science. "Spectroscopic Studies and Thermal Analysis of New Azo Dyes Ligands and their Complexes with some Transition of Metal Ions." Baghdad Science Journal 13, no. 3 (December 30, 2018): 511–23. http://dx.doi.org/10.21123/bsj.13.3.511-523.

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New Azo ligands HL1 [2-Hydroxy-3-((5-mercapto-1,3,4-thiadiazol-2-yl)diazenyl)-1-naphth aldehyde] and HL2 [3-((1,5-Dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)diazenyl)-2-hydroxy-1-naphthaldehyde] have been synthesized from reaction (2-hydroxy-1-naphthaldehyde) and (5-amino-1,3,4-thiadiazole-2-thiol) for HL1 and (4-amino-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one) for HL2. Then, its metal ions complexes are synthesized with the general formula; [CrHL1Cl3(H2O)], [VOHL1(SO4)] [ML1Cl(H2O)] where M = Mn(II), Co(II), Ni(II) and Cu(II), and general formula; [Cr(L2)2 ]Cl and [M(L2)2] where M = VO(II), Mn(II), Co(II), Ni(II) and Cu(II) are reported. The ligands and their metal complexes are characterized by phisco- chemical spectroscopic techniques (FT.IR, Mass, UV-Vis, 1H and 13C-NMR, TGA, (C.H.N.), molar conductivity, Atomic Absorbance, Chloride containing magnetic susceptibility). The spectral data suggest that the (HL1) behaves as a bidentate ligand in all complexes, whereas (HL2) behaves as a tridentate ligand for all complexes; bidentate ligand in Vanadium complex is coordinated with the metal ions through azo nitrogen and oxygen atoms. Theoretical studies of these ligands and their metal complexes in gas phase using Hyper chem.8. Studies of these compounds are prepared for their bacterial activity

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Hanack, M., M. Fiedler, and L. R. Subramanian. "Phthalocyaninatoiron complexes with tridentate ligands." Synthetic Metals 100, no. 1 (March 1999): 123–30. http://dx.doi.org/10.1016/s0379-6779(98)00165-9.

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Wadayama, Kosei, Tsugiko Takase, and Dai Oyama. "Selective synthesis and crystal structures of manganese(I) complexes with a bi- or tridentate terpyridine ligand." Acta Crystallographica Section E Crystallographic Communications 76, no. 7 (June 26, 2020): 1139–42. http://dx.doi.org/10.1107/s2056989020008178.

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The crystal structures of two manganese(I) complexes with a different coordination mode of the supporting ligand are reported: fac-bromidotricarbonyl(4′-phenyl-2,2′:6′,2′′-terpyridine-κ2 N,N′)manganese(I), [MnBr(C21H15N3)(CO)3], I, and cis-bromidodicarbonyl(4′-phenyl-2,2′:6′,2′′-terpyridine-κ3 N,N′,N′′)manganese(I), [MnBr(C21H15N3)(CO)2], II. In both complexes, the manganese(I) atom is coordinated by terminal carbonyl ligands, a bromide ion, and a 4′-phenyl-2,2′:6′,2′′-terpyridine ligand within a distorted octahedral environment. In I, the metal ion is facially coordinated by three carbonyl ligands and the terpyridine ligand binds in a bidentate fashion. The non-coordinating nitrogen atom in the terpyridine ligand is positioned on the side opposite to the bromido ligand. In II, the metal ion is coordinated by two carbonyl ligands in a cis configuration and the terpyridine ligand binds in a tridentate fashion; notably, one carbonyl and the trans bromido ligand are mutually disordered over two positions. In I, the complex molecules are linked by C—H...Br hydrogen bonds. In II, aromatic π–π contacts are present, as well as pairs of C—H...Br and C—H...O hydrogen bonds.

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Ashbridge, Zoe, Elisabeth Kreidt, Lucian Pirvu, Fredrik Schaufelberger, Joakim Halldin Stenlid, Frank Abild-Pedersen, and David A. Leigh. "Vernier template synthesis of molecular knots." Science 375, no. 6584 (March 4, 2022): 1035–41. http://dx.doi.org/10.1126/science.abm9247.

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Molecular knots are often prepared using metal helicates to cross the strands. We found that coordinatively mismatching oligodentate ligands and metal ions provides a more effective way to synthesize larger knots using Vernier templating. Strands composed of different numbers of tridentate 2,6-pyridinedicarboxamide groups fold around nine-coordinate lanthanide (III) ions to generate strand-entangled complexes with the lowest common multiple of coordination sites for the ligand strands and metal ions. Ring-closing olefin metathesis then completes the knots. A 3:2 (ditopic strand:metal) Vernier assembly produces +3 1 #+3 1 and −3 1 #−3 1 granny knots. Vernier complexes of 3:4 (tetratopic strand:metal) stoichiometry selectively form a 378-atom-long trefoil-of-trefoils triskelion knot with 12 alternating strand crossings or, by using opposing stereochemistry at the terminus of the strand, an inverted-core triskelion knot with six alternating and six nonalternating strand crossings.

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Ismaiel Mahjoub Muslah, Safa, Ammar J. Alabdali, and Nasser D. Shaalan. "Synthesis of Binuclear Complexes of Cu (II), Ni (II) and Cr (III) Metal Ions Derived from Di-Imine Compound as Biterminal Binding Site Ligand." Al-Nahrain Journal of Science 23, no. 4 (December 1, 2020): 19–28. http://dx.doi.org/10.22401/anjs.23.4.04.

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The research is concerning synthesis of two di-imine ligands derived from thiadiazole heterocyclic compounds. 1, 3, 4-thiadiazole-2, 5-dihydrazino is considered as ligand (L1) and starting essential compound that used as precursor to synthesize the new ligand (2, 2'-(((1,3,4-thiadiazole-2,5-diyl)bis(hydrazin-2yl1ylidene))bis (methaneylylide)) diphenol (L2). Six new complexes were derived from the ligands using some transition metal ions like Cu(II), Ni(II), and Cr(III).The synthesized compounds characterized by infra-red, ultra-violet-visible and gas chromatography-mass spectroscopy, conductivity, and thermal analysis. The coordination modes were suggested to be N2from two terminals to form binuclear complexes. The mentioned characterization methods showed that the prepared complexes may have chelation pattern (bidentate or tridentate) depending on the suggested geometry (square planer or octahedral) and the type of ligand.

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24

Zhang, Long, Tao Yan, Ying-Feng Han, F. Ekkehardt Hahn, and Guo-Xin Jin. "Synthesis of a new type of alkene metal complex using face-capping thione-alkene ligands." Dalton Transactions 44, no. 19 (2015): 8797–800. http://dx.doi.org/10.1039/c5dt01311a.

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25

Sadek, Hassan Ahmed. "Synthesis, Spectroscopic and Thermogravimetric studies on some Transition metal complexes with hydrazone ligands." JOURNAL OF ADVANCES IN CHEMISTRY 12, no. 3 (February 16, 2016): 4224–36. http://dx.doi.org/10.24297/jac.v12i3.2163.

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Complexes of Cu (II) and Ni (II) derived from 2-amino-N’-(2-hydroxybenzylidene) benzohydrazide (ASH) , 2-amino-N’-benzylidenebenzohydrazide (ABH), N’-(3-phenylallylidene)-2-((3-phenylallylidene)amino)benzohydrazide (ACH), and N’-(4-methoxybenzylidene)-2-((4-methoxybenzylidene)amino)benzohydrazide (AAH) have been synthesized and characterized by elemental and thermal analysis(TGA), IR, U.V-Visible, 1 H NMR (Ligands) spectral studies, magnetic susceptibility, atomic absorption and molar conductivity measurements, the ligand (ASH) act as tridentate with ONO donor sites, the bonding sites are carbonyl oxygen , azomethine nitrogen and phenolate oxygen, the other ligands act as bidentate with ON donor sites, the bonding sites are carbonyl oxygen, azomethine nitrogen, the metal complexes exhibit different geometrical structures such as square pyramidal, tetrahedral, square planar and octahedral. The Coats-Redfern equation has been used to calculate the thermodynamic parameters for different thermal decomposition steps of some complexes.

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26

Decken, Andreas, Robert A. Gossage, and Paras N. Yadav. "Oxazoline chemistry. Part VIII. Synthesis and characterization of a new class of pincer ligands derived from the 2-(o-anilinyl)-2-oxazoline skeleton Applications to the synthesis of group X transition metal catalysts." Canadian Journal of Chemistry 83, no. 8 (August 1, 2005): 1185–89. http://dx.doi.org/10.1139/v05-163.

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The synthesis and characterization of a new and readily synthesized class of potentially anionic pincer ligands with C1 point group symmetries is described. These materials can be made via amide coupling of a 2-(2′-anilinyl)-2-oxazoline unit with picolinic acid; the incorporation of enantiopure oxazoline fragments facilitates the construction of chiral C1 pincers. Treatment of the free ligands with Pd metal sources leads to the formation of amidoPd pincer complexes in good yield. One of these Pd complexes has been characterized by single crystal X-ray diffraction methods, which confirms the proposed tridentate binding mode of the ligand and the formation of an amido NPd bond. The metal complexes have been shown to be suitable precusors for catalytically active Pd species that are useful for CC bond forming reactions, notably the Heck reaction under standard conditions. Key words: oxazoline, 4,5-dihydro-2-oxazole, palladium, pincer ligand, amido, Heck reaction.

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27

Onyiriuka, Emmanuel C., and Alan Storr. "Synthesis and characterization of transition metal complexes containing novel, unsymmetric tridentate organogallate ligands." Canadian Journal of Chemistry 65, no. 6 (June 1, 1987): 1367–74. http://dx.doi.org/10.1139/v87-231.

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Two novel unsymmetric tridentate anionic organogallate ligands have been synthesized and their coordinating properties toward a number of transition metal carbonyl species, and toward the "NINO" moiety, have been investigated. The ligand [Me2Ga(N2C3H3)•O(C5H3N)CH2NMe2]−, La, has shown unusual behaviour in that it produces both the fac and mer octahedral isomers, LaM(CO)3, (M = Mn or Re), on reaction with Mn(CO)5Br and [Re(CO)4Cl]2, respectively. In addition, this ligand gives a stable Rh(III) addition product, LaRh(Me)(I)CO, on reaction of LaRh(CO) with Mel. The second ligand, [Me2Ga(N2C3H3)•O(C9H6N)]−, Lq, containing a quinolyl moiety in addition to a pyrazolyl group attached to dimethyl-gallium, displays more predictable behaviour in its coordinating properties.

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28

Leovac, Vukadin, Ljiljana Vojinovic, Katalin Mesaros-Secenji, and Valerija Cesljevic. "Transition metal complexes with thiosemicarbazide-based ligands, part 46: Synthesis and physico-chemical characterization of mixed ligand cobalt(III)-complexes with salicylaldehyde semi-, thiosemi- an." Journal of the Serbian Chemical Society 68, no. 12 (2003): 919–27. http://dx.doi.org/10.2298/jsc0312919l.

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Mixed ligand octahedral cobalt(III) complexes with the tridentate salicylaldehyde semi-, thiosemi- and isothiosemicarbazone and pyridine of general formula [CoIII(L1-3)(py)3]X(H2L1=salicylaldehyde semicarbazone X=[CIICl3(py)]-, ClO4-.H2O, I-. 0.5 I2; H2L2=salicylaldehyde thiosemicarbazone, X=[CoIICl3(py)]-, CoIIBr3(py)]-, ClO4-. H2O, I3-; H2L3 = salicylaldehyde S-methylisothiosemicarbazone, X=[CoIIBr3(py)]-, ClO4-. H2O, BF4-) were synthesized. The tridentate coordination of all the three dianionic forms of the ligands involves the phenol oxygen, hydrazine nitrogen and the chalcogen (O or S) in case of salicylaldehyde semi thiosemicarbazone and the terminal nitrogen atom in the case of isothiosemicarbazone. For all the complexes, a meridial octahedral arrangement is proposed, which is a consequence of the planarity of the chelate ligand. The compounds were characterized by elemental analysis molar conductivity, magnetic susceptibility, IR and electronic absorption spectra. The thermal decomposition of the complexes was investigated by thermogravimetry, coupled TG-MS measurements and DSC.

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29

Abdullahi, B. L., and I. T. Siraj. "Synthesis, characterization and antimicrobial activities of Schiff base complexes derived from Salicylaldehyde and amino acid (isoleucine)." Bayero Journal of Pure and Applied Sciences 15, no. 1 (December 9, 2022): 113–18. http://dx.doi.org/10.4314/bajopas.v15i1.15.

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Complexes of Fe(II), Co(II), Cu(II), and Zn(II) with a Schiff base derived from salicylaldehyde and isoleucine were successfully synthesized. All complexes were distinctly colored and were characterized by molar conductance, magnetic susceptibility, infrared and UV spectroscopy. Infrared spectroscopy shows the Schiff base ligand is coordinated to the central metal ion in a tridentate manner through the N-atom of the azomethine and two oxygen of the phenol and carboxylate. All complexes contain two ligands molecules per metal ion (ML2). An octahedral geometry is proposed for the metal complexes. Antimicrobial study of the complexes was undertaken against five pathogenic bacteria strains and two fungi, mucus species and Aspergillus fumigates. The result reveal that most of the complexes and particularly Co (II) and Zn (II) have a much enhanced activity against Staphyllococcus aureus, Escherichia coli and Klebsiella pneumoniae.

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30

Tak, Rajkumar, Manish Kumar, Rukhsana I. Kureshy, Manoj Kumar Choudhary, Noor-ul H. Khan, Sayed H. R. Abdi, and Hari C. Bajaj. "Enantioselective syntheses of β-amino alcohols catalyzed by recyclable chiral Fe(iii) metal complex." RSC Advances 6, no. 9 (2016): 7693–700. http://dx.doi.org/10.1039/c5ra23600b.

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An efficient asymmetric desymmetrization of meso-epoxides with anilines catalyzed by a series of simple and environmentally benign in situ generated Fe(iii) complexes based on chiral tridentate ligands L1–L7 was carried out at rt.

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31

Roymuhury, Sagnik K., Mrinmay Mandal, Debashis Chakraborty, and Venkatachalam Ramkumar. "Homoleptic titanium and zirconium complexes exhibiting unusual Oiminol–metal coordination: application in stereoselective ring-opening polymerization of lactide." Polymer Chemistry 12, no. 27 (2021): 3953–67. http://dx.doi.org/10.1039/d1py00237f.

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The synthesis and characterization of novel homoleptic Ti and Zr complexes with tridentate ONO-type Schiff base ligands and their catalytic activities towards the ring-opening polymerization (ROP) of lactide are reported.

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32

Al-Radadi, Najlaa S., Ehab M. Zayed, Gehad G. Mohamed, and Hayam A. Abd El Salam. "Synthesis, Spectroscopic Characterization, Molecular Docking, and Evaluation of Antibacterial Potential of Transition Metal Complexes Obtained Using Triazole Chelating Ligand." Journal of Chemistry 2020 (February 24, 2020): 1–12. http://dx.doi.org/10.1155/2020/1548641.

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Mononuclear chelates of Ni(II), Co(II), Fe(III), Cd(II), and Cu(II) derived from triazole novel tridentate ligands were prepared and characterized by different spectroscopic methods. The metal to ligand ratio was 1 : 2, which was revealed by elemental analysis. All the complexes were electrolytic in nature as suggested by the conductivity measurements. IR pointed out that the coordination of the triazole ligand toward the metal ions was carried out through N amino and S thiophenolic atoms. The complexes were found to have octahedral geometry, and their thermal stability was also studied. The XRD spectrum of Co(II) and Fe(III) complexes concluded their crystalline structure. The parent ligand and its chelates were investigated for antimicrobial potential. Bioassay of all triazole complexes showed increased activity as compared to that of the ligand. The complexes having Ni(II), Co(II), and Cu(II) ions as metal center exhibited superior antibacterial activity in opposition to Gram-positive (B. subtilis and S. pyogenes) and Gram-negative (E. coli and P. vulgaris) bacterium as compared to standard.

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33

Zhong, Tingshan, Jixing Zhao, and Hao Lei. "Trianionic binucleating bis(trityl)/aryloxide ligands and their lithium, magnesium, and zinc complexes." Canadian Journal of Chemistry 98, no. 8 (August 2020): 453–59. http://dx.doi.org/10.1139/cjc-2020-0139.

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A series of lithium complexes with trianionic bis(trityl)/aryloxide ligands were prepared by triple deprotonation of phenols with two ortho-diarylmethyl substituents. Transmetalation with one of the lithium complexes via salt metathesis resulted in the synthesis of corresponding Mg and Zn complexes, which showed distinct coordination stoichiometry and structures. The metal complexes were characterized by multi-nuclear NMR, UV–vis, and infrared spectroscopy. Additionally, the redox property of a trilithium compound was investigated by electrochemical methods. X-ray crystallography revealed that the new bis(trityl)/aryloxide ligands could simultaneously bind to two nearby metal centers both in chelating κ2-O,C fashion, making themselves rare examples of tridentate binucleating alkyl/aryloxo scaffolds.

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34

Lashanizadegan, Maryam, and Marzieh Sarkheil. "Solvent-dependent synthesis and mono-hydrolysis of di-Schiff base of (+/-)trans-1,2-cyclohexanediamine and 2-pyridinecarboxaldehyde in Cu(II), Co(II) and Zn(II) complexes." Journal of the Serbian Chemical Society 77, no. 11 (2012): 1589–97. http://dx.doi.org/10.2298/jsc111203035l.

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The Schiff base ligand trans-N,N?-bis[2-pyridinecarboxylidene] cyclohexane-1,2-diamine (L) was synthesized. This ligand when stirred with 1 equiv of MCl2.xH2O (M = Cu, Co, Zn) in ethanol, undergoes partial hydrolysis of the imino bond and the result tridentate ligand (L') and immediately forms the complexes with N3 coordination sphere. The reactions of L with MCl2.xH2O (M = Cu, Co, Zn) in THF give complexes [ML]Cl2. The ligand (L), complexes [M(L')Cl]Cl and [ML]Cl2 were characterized by elemental analysis, UV-Vis, FT-IR, 1H NMR, GC/MS and luminescence properties. The 1H NMR spectra of the ligand and its diamagnetic complexes were recorded in CDCl3 and DMSO solvents, respectively. Obtained data confirm that the donor atoms N in ligand coordinated to the metal ions. The luminescence studies show ligands and their complexes display intraligand (?- ?

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35

Anarado, Chigozie John Onyinye, Chinasa Grace Iziga, Collins Ugochukwu Ibeji, Ilknur Babahan-Bircan, Burak Coban, Füsun Cömert, and Charity Ebere Anarado. "Synthesis and Characterization of 4-amino-N'-[(1E)-1-(2-hydroxy-6-methyl-4-oxo-4H-pyran-3-yl)ethylidene]benzohydrazide and its Cu(II), Ni(II), Zn(II) and Mn(II) Complexes." Molekul 18, no. 2 (July 10, 2023): 307. http://dx.doi.org/10.20884/1.jm.2023.18.2.8186.

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New benzohydrazone compound, 4-amino-N'-[(1E)-1-(2-hydroxy-6-methyl-4-oxo-4H-pyran-3-yl)ethylidene] benzohydrazide (HL1) and its Cu(II), Ni(II), Zn(II) and Mn(II) complexes were synthesized. The structures of HL1 and its complexes were elucidated by elemental analysis and IR, UV-Vis, 1H and 13C NMR spectroscopy and mass spectrometry. The infrared spectral data of the complexes revealed that HL1 coordinated with the metal ions through azomethine nitrogen, enolic oxygen and amide carbonyl oxygen atoms, hence, HL1 behaves as a monobasic tridentate ligand. UV-Vis data revealed that Zn(II) and Mn(II) complexes adopted octahedral geometry, while Cu(II) and Ni(II) complexes had five-coordinate and square-planar geometries respectively. The mass spectra data and elemental analysis values are in accordance with the calculated values for the suggested molecular formula of the complexes, a confirmation of the 1:1 ligand to metal stoichiometry in case of Cu(II) complex and 2:1 ligands to metal stoichiometry in case of the other complexes.

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36

Baker, AT, DC Craig, G. Dong, and AD Rae. "Metal Complexes of 1,3-Bis(Pyridin-2-yl)pyrazole: Spectral, Magnetic and Structural Studies." Australian Journal of Chemistry 48, no. 6 (1995): 1071. http://dx.doi.org/10.1071/ch9951071.

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Bis(ligand)iron(II) and nickel(II) complexes of the asymmetric tridentate ligand 1,3-bis(pyridin-2-yl) pyrazole , L, have been prepared. The iron(II) complex, [FeL2] [PF6]2, is high-spin in the solid state over the temperature range 304-102 K, with a magnetic moment of 5.27 BM at room temperature. The crystal structure of bis (1,3-bis(pyridin-2-yl) pyrazole )iron(II) bis (hexafluorophosphate ) has been determined by single-crystal X-ray diffractometry. The compound crystallized as yellow prisms, with the structure being disordered in the tetragonal space group P421c with Z = 2. Crystal data a = b = 8.785(1) Ǻ, c = 19.804(6) Ǻ. The iron(II) centre is in an N6 environment, where the six donor nitrogen atoms are provided by the two tridentate heterocyclic ligands. The complex cation has an approximately octahedral structure exhibiting tetragonal compression. The observed Fe-N(pyridine) and Fe-N( pyrazole ) distances are 2.308(4) and 2.019(7) Ǻ respectively, with the Fe-N(pyridine) distance being the longest observed to date.

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37

Aleksanyan, Diana V., Svetlana G. Churusova, Ekaterina Yu Rybalkina, and Vladimir A. Kozlov. "Rhenium(I) Complexes with Pincer Ligands as a New Class of Potential Antitumor Agents." Proceedings 22, no. 1 (August 8, 2019): 43. http://dx.doi.org/10.3390/proceedings2019022043.

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Transition metal complexes attract continuous research interest as potential antitumor agents. The most popular compounds are ruthenium, gold, titanium, osmium, iridium, zinc, and palladium complexes, which have already displayed cytotoxic features that are not typical for classical platinum-containing chemotherapeutic agents. Substantially lower attention is drawn to organometallic compounds of rhenium. However, the known examples of cytotoxic organometallic rhenium derivatives with bidentate heterocyclic, organophosphorus, labile alkoxide, and hydroxide ligands render further studies in this field very promising. As for their analogs with multidentate ligands, a literature survey has revealed only a few examples of cytotoxic rhenium complexes, whereas the antitumor activity of cyclometallated derivatives has not been studied at all. At the same time, it is known that the use of pincer-type ligands having specific tridentate monoanionic frameworks, which offer multiple options for directed structural modifications, allows one to finely tune the thermodynamic and kinetic stability of the resulting metal complexes. Therefore, we synthesized and studied the cytotoxic properties of a series of rhenium(I) complexes with tridentate pincer-type ligands based on functionalized carboxamides bearing ancillary donor groups both in the acid and amine components. It was shown that the target complexes can be obtained not only by the conventional solution-based method, but also under solvent-free conditions according to the solid-phase methodology recently developed in our group. The results obtained were used to define the main structure–activity relationships for a principally new class of potential antitumor agents and to choose the most promising compounds for further studies in order to create new pharmaceuticals.

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38

Payen, Leo, Lukas Kletsch, Tobias Lapić, Mathias Wickleder, and Axel Klein. "C–H Metalation of Terpyridine Stereoisomers with Ni(II), Pd(II), and Pt(II)." Inorganics 11, no. 4 (April 21, 2023): 174. http://dx.doi.org/10.3390/inorganics11040174.

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Ni(II), Pd(II), and Pt(II) complexes [M(Y-terpy)X] (X = Cl or Br) containing the tridentate N^C^N-cyclometalating 2,3′:5′,2″and 2,2′:4′,2″ stereoisomers of the well-known tridentate N^N^N ligand 2,2′:6′,2″-terpyridine (terpy) were synthesised in moderate to good yields through C–H activation. For the Pt complexes, the phenyl ethynide derivatives [Pt(Y-terpy)(C≡CPh)] were also obtained under Sonogashira conditions. In contrast to this, C^N^N cyclometalated complexes using the 2,2′:6′,3″- and 2,2′:6′4″-terpy isomers were not obtained. Comparison of the N^C^N complexes of the cyclometalated 2,3′:5′,2″- and 2,2′:4′,2″-terpy ligands with complexes [M(dpb)Cl] of the prototypical N^C^N cyclometalating ligand dpb− (Hdpb = 2,6-diphenyl-pyridine) showed higher potentials for the terpy complexes for the ligand-centred reductions in line with the superior π-accepting properties of the terpy ligands compared with dpb. Metal-centred oxidations were facilitated by the dpb ligand carrying a central σ-donating phenyl group instead of a metalated pyridine moiety. The same trends were found for the long-wavelength absorptions and the derived electrochemical and optical band gaps. The lower σ-donating capacities of the cyclometalated terpy derivatives is also confirmed by a reduced trans influence in the structure of [Ni(2,3′:5′,2″-terpy)Br0.14/OAc0.86]. Attempts to re-crystallise some poorly soluble Pd(II) and Pt(II) complexes of this series under solvothermal conditions (HOAc) gave two structures with N-protonated cyclometalated pyridine moieties, [Pt(2,3′:5′,2″-terpyH)Cl].Cl and [Pd(2,3′:5′,2″-terpyH)Cl2].

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39

Yadav, Jyoti, and Jai Devi. "Antimicrobial and Antioxidant Activities of Diorganotin(IV) Complexes Synthesized from 1,2,4-Triazole Derivatives." Asian Journal of Chemistry 32, no. 10 (2020): 2553–58. http://dx.doi.org/10.14233/ajchem.2020.22819.

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Novel diorganotin(IV) complexes were synthesized from 1,2,4-triazole Schiff base ligands which were synthesized by reaction between the 4-amino-5-phenyl-1,2,4-triazole-3-thiol and salicyaldehyde derivatives. The bonding and geometry of the diorganotin(IV) complexes were evaluated by using different spectroscopic techniques such as FT-IR, mass, 1H, 13C & 119Sn NMR. The different spectroscopic techniques revealed the tridentate (ONS) mode of chelation of Schiff base ligands and pentacoordinated environment around the central tin metal which was satisfied with azomethine nitrogen, phenolic oxygen, thiolic sulfur and metal-carbon bond of alkyl/aryl group. The Schiff base ligands and their organotin(IV) complexes were tested for their in vitro antimicrobial and antioxidant activities to examine the biological outline of complexes in comparison to standard drugs. The results of activities data revealed that diorganotin(IV) complexes are more active than Schiff base ligands and some diorganotin(IV) complexes are even more active than the standard drugs. In all the synthesized complexes, compound 9 (Bu2SnL2) and 10 (Ph2SnL2) were most potent and can be used in future clinical trials.

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40

Megger, Dominik A., Kristin Rosowski, Christian Radunsky, Jutta Kösters, Barbara Sitek, and Jens Müller. "Structurally related hydrazone-based metal complexes with different antitumor activities variably induce apoptotic cell death." Dalton Transactions 46, no. 14 (2017): 4759–67. http://dx.doi.org/10.1039/c6dt04613d.

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Three new metal complexes bearing a tridentate hydrazone-based ligand were synthesized and structurally characterized. Depending on the metal ion, the complexes show remarkably different antitumor activities.

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41

Pilichos, Evangelos, Evangelos Spanakis, Evangelia-Konstantina Maniaki, Catherine P. Raptopoulou, Vassilis Psycharis, Mark M. Turnbull, and Spyros P. Perlepes. "Diversity of Coordination Modes in a Flexible Ditopic Ligand Containing 2-Pyridyl, Carbonyl and Hydrazone Functionalities: Mononuclear and Dinuclear Cobalt(III) Complexes, and Tetranuclear Copper(II) and Nickel(II) Clusters." Magnetochemistry 5, no. 3 (July 1, 2019): 39. http://dx.doi.org/10.3390/magnetochemistry5030039.

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Syntheses, crystal structures and characterization are reported for four new complexes [Cu4Br2(L)4]Br2 (1), [Ni4(NO3)2(L)4(H2O)](NO3)2 (2), [Co2(L)3](ClO4)3 (3) and [Co(L)2](ClO4) (4), where L− is the monoanion of the ditopic ligand N′-(1-(pyridin-2-yl)ethylidene)pyridine-2-carbohydrazide (LH) built on a picolinoyl hydrazone core fragment, and possessing a bidentate and a tridentate coordination pocket. The tetranuclear cation of 1·0.8H2O·MeOH is a strictly planar, rectangular [2 × 2] grid. Two 2.21011 L− ligands bridge adjacent CuII atoms on the short sides of the rectangle through their alkoxide oxygen atoms, and two 2.11111 ligands bridge adjacent CuII atoms on the long sides of the rectangle through their diazine groups; two metal ions are 5-coordinate and two are 6-coordinate. The tetranuclear cation of 2·0.2H2O·3EtOH is a square [2 × 2] grid. The two 6-coordinate NiII atoms of each side of the square are bridged by the alkoxide O atom of one 2.21011 L− ligand. The dinuclear cation of 3·0.8H2O·1.3MeOH contains two low-spin octahedral CoIII ions bridged by three 2.01111 L− ligands forming a pseudo triple helicate. In the mononuclear cation [Co(L)2]+ of complex 4, the low-spin octahedral CoIII center is coordinated by two tridentate chelating, meridional 1.10011 ligands. The crystal structures of the complexes are stabilized by a variety of π–π stacking and/or H-bonding interactions. Compounds 2, 3 and 4 are the first structurally characterized nickel and cobalt complexes of any form (neutral or anionic) of LH. The 2.01111 and 1.10011 coordination modes of L−, observed in the structures of complexes 3 and 4, have been crystallographically established for the first time in coordination complexes containing this anionic ligand. Variable-temperature, solid-state dc magnetic susceptibility and variable-field magnetization studies at 1.8 K were carried out on complexes 1 and 2. Antiferromagnetic metal ion···metal ion exchange interactions are present in both complexes. The study reveals that the cation of 1 can be considered as a practically isolated pair of strongly antiferromagnetically coupled (through the diazine group of L−) dinulear units. The susceptibility data for 2 were fit to a single-J model for an S = 1 cyclic tetramer. The values of the J parameters have been rationalized in terms of known magnetostructural correlations. Spectral data (infrared (IR), ultraviolet/visible (UV/VIS), 1H nuclear magnetic resonance (NMR) for the diamagnetic complexes) are also discussed in the light of the structural features of 1–4 and the coordination modes of the organic and inorganic ligands that are present in the complexes. The combined work demonstrates the ligating flexibility of L−, and its usefulness in the synthesis of complexes with interesting structures and properties.

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42

Silva, Francisco, Célia Fernandes, Maria Paula Cabral Campello, and António Paulo. "Metal complexes of tridentate tripod ligands in medical imaging and therapy." Polyhedron 125 (March 2017): 186–205. http://dx.doi.org/10.1016/j.poly.2016.11.040.

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43

Jirgi, Bhikshappa S., Gopal L. Tembe, Maruti H. Sonar, and A. Sitaramachandra Murty. "Transition metal complexes of novel tridentate S,N,O donor ligands." Transition Metal Chemistry 18, no. 2 (April 1993): 171–74. http://dx.doi.org/10.1007/bf00139950.

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44

Zhang, Xiu-Qing, Qing Yu, He-Dong Bian, Shi-Ping Yan, Dai-Zheng Liao, Wen Gu, and Hong Liang. "New Coordination Polymers of Lanthanide(III) with Tetrazole-1-acetic Acid: Synthesis, Crystal Structures, and Magnetic Properties." Australian Journal of Chemistry 61, no. 4 (2008): 303. http://dx.doi.org/10.1071/ch07439.

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New coordination polymers {[Ln(tza)3(H2O)2]·mH2O}n (Ln = LaIII 1 and PrIII 2, m = 2; Ln = NdIII 3, m = 1.5) and {[Sm2(tza)6(H2O)5]·H2O}n 4 (Htza = tetrazole-1-acetic acid) have been synthesized and characterized by IR spectroscopy, elemental analysis, X-ray crystallography, and magnetic measurements. The Htza ligand coordinates to the lanthanide cations through the carboxylate group in a monodentate, bridging bidentate coordination mode or bridging tridentate to two metal centres. Complexes 1 and 2 are isostructural. Complex 3 has a similar structure to 1 and 2, but the arrangement of ligands has changed. Complex 4 consists of two types of metallic molecules. Magnetic measurements show weak antiferromagnetic coupling between the metal centres in complexes 2 and 3.

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45

Mishra, A. P., and Monika Soni. "Synthesis, Structural, and Biological Studies of Some Schiff Bases and Their Metal Complexes." Metal-Based Drugs 2008 (July 27, 2008): 1–7. http://dx.doi.org/10.1155/2008/875410.

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New bidentate or tridentate Schiff bases and their VO(II) and Co(II) complexes formed by the condensation of methyl isobutyl ketone with nicotinamide (mna)/2-amino-4-chlorophenol (map) and 2-hydroxy acetophenone with nicotinamide (han)/isoniazide (hai). Physicochemical characterization has been carried out to determine the structure of the complexes. The FAB mass and thermal data show degradation pattern of the complexes. XRD analysis reveals that all the studied complexes crystallize as tetragonal crystal system. Some of the complexes have been screened for their antimicrobial activity by the well diffusion technique using DMSO as solvent on different species of pathogenic bacteria/fungi, that is, E. coli, S. aureus, S. fecalis, A. niger, T. polysporum, and their antimicrobial potency have been discussed. It has been found that all the complexes are antimicrobially active and show higher activity than the free ligand. Metal chelation affects significantly the antimicrobial/bioactive behavior of the organic ligands.

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46

Assoumatine, Tokouré, and Helen Stoeckli-Evans. "Silver(I) nitrate complexes of three tetrakis-thioether-substituted pyrazine ligands: metal–organic chain, network and framework structures." Acta Crystallographica Section E Crystallographic Communications 73, no. 3 (February 24, 2017): 434–40. http://dx.doi.org/10.1107/s2056989017002791.

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The reaction of the ligand 2,3,5,6-tetrakis[(methylsulfanyl)methyl]pyrazine (L1) with silver(I) nitrate led to {[Ag(C12H20N2S4)](NO3)}n, (I),catena-poly[[silver(I)-μ-2,3,5,6-tetrakis[(methylsulfanyl)methyl]pyrazine] nitrate], a compound with a metal–organic chain structure. The asymmetric unit is composed of two half ligands, located about inversion centres, with one ligand coordinating to the silver atoms in a bis-tridentate manner and the other in a bis-bidentate manner. The charge on the metal atom is compensated for by a free nitrate anion. Hence, the silver atom has a fivefold S3N2coordination sphere. The reaction of the ligand 2,3,5,6-tetrakis[(phenylsulfanyl)methyl]pyrazine (L2) with silver(I) nitrate, led to [Ag2(NO3)2(C32H28N2S4)]n, (II), poly[di-μ-nitrato-bis{μ-2,3,5,6-tetrakis[(phenylsulfanyl)methyl]pyrazine}disilver], a compound with a metal–organic network structure. The asymmetric unit is composed of half a ligand, located about an inversion centre, that coordinates to the silver atoms in a bis-tridentate manner. The nitrate anion coordinates to the silver atom in a bidentate/monodentate manner, bridging the silver atoms, which therefore have a sixfold S2NO3coordination sphere. The reaction of the ligand 2,3,5,6-tetrakis[(pyridin-2-ylsulfanyl)methyl]pyrazine (L3) with silver(I) nitrate led to [Ag3(NO3)3(C28H24N6S4)]n, (III), poly[trinitrato{μ6-2,3,5,6-tetrakis[(pyridin-2-ylsulfanyl)methyl]pyrazine}trisilver(I)], a compound with a metal–organic framework structure. The asymmetric unit is composed of half a ligand, located about an inversion centre, that coordinates to the silver atoms in a bis-tridentate manner. One pyridine N atom bridges the monomeric units, so forming a chain structure. Two nitrate O atoms also coordinate to this silver atom, hence it has a sixfold S2N2O2coordination sphere. The chains are linkedviaa second silver atom, located on a twofold rotation axis, coordinated by the second pyridine N atom. A second nitrate anion, also lying about the twofold rotation axis, coordinates to this silver atomviaan Ag—O bond, hence this second silver atom has a threefold N2O coordination sphere. In the crystal of (I), the nitrate anion plays an essential role in forming C—H...O hydrogen bonds that link the metal–organic chains to form a three-dimensional supramolecular structure. In the crystal of (II), the metal–organic networks (lying parallel to thebcplane) stack up thea-axis direction but there are no significant intermolecular interactions present between the layers. In the crystal of (III), there are a number of C—H...O hydrogen bonds present within the metal–organic framework. The role of the nitrate anion in the formation of the coordination polymers is also examined.

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Seleem, H. S. M., M. El-Behairy, M. M. Masshaly, and H. H. Mena. "Thermodynamics of complexation of isatin-3-thiosemicarbazone (HIT) and other related derivatives with some metal ions." Journal of the Serbian Chemical Society 67, no. 4 (2002): 243–56. http://dx.doi.org/10.2298/jsc0204243s.

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Proton-ligand formation constants of isatin-3-thiosemicarbazone (HIT) N-acetylisatin-3-thiosemicarbazone (HAIT) and 5-(p-nitrobenzoyl)-1,2,4-triazino[5,6-b]indole- 3-thione (HBITr) ligands and their corresponding metal-ligand formation constants with Mn2+, Fe3+, Co2 Ni2+, Cu2+, Zn2+, Cd2+, UO22+ and Th4+ ions were determined pH-metrically at 10, 20, 30 and 40 ?C in 75 %(v/v) ethanol?water. The thermodynamic parameters (?G, ?H and ?S) were also evaluated. It was found that both log K1 and ??H1, for HIT and HAIT-complexes are somewhat larger than log K2 and ??H2, indicating a change in the dentate character of these ligands from tridentate (ONN-donors) in 1:1 chelates to bidentate (ON-donors) in 1:2; M:L chelates. In contrast, the values of logK2 and ??H2 for HBITr-complexes are somewhat larger than logK1 and ??H1, indicating a strong trans-effect for the second coordination. The dissociation process is non-spontaneous endothermic and entropically unfavorable while the complexation process is spontaneous, exothermic and entropically favorable. The thermodynamic parameters were separated into their electrostatic (el) and non-electrostatic (non) constituents.

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Holland, Amanda M., Allen G. Oliver, and Vlad M. Iluc. "Iron pyrrole-based PNP pincer ligand complexes as catalyst precursors." Acta Crystallographica Section C Structural Chemistry 73, no. 7 (June 28, 2017): 569–74. http://dx.doi.org/10.1107/s2053229617009287.

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The structure of a pincer ligand consists of a backbone and two `arms' which typically contain a P or N atom. They are tridentate ligands that coordinate to a metal center in a meridional configuration. A series of three iron complexes containing the pyrrole-based PNP pincer ligand 2,5-bis[(diisopropylphosphanyl)methyl]pyrrolide (PNpyrP) has been synthesized. These complexes are possible precursors to new iron catalysts. {2,5-Bis[(diisopropylphosphanyl)methyl]pyrrolido-κ3 P,N,P′}carbonylchlorido(trimethylphosphane-κP)iron(II), [Fe(C18H34NP2)Cl(C3H9P)(CO)] or [Fe(PNpyrP)Cl(PMe3)(CO)], (I), has a slightly distorted octahedral geometry, with the Cl and CO ligands occupying the apical positions. {2,5-Bis[(diisopropylphosphanyl)methyl]pyrrolido-κ3 P,N,P′}chlorido(pyridine-κN)iron(II), [Fe(C18H34NP2)Cl(C5H5N)] or [Fe(PNpyrP)Cl(py)] (py is pyridine), (II), is a five-coordinate square-pyramidal complex, with the pyridine ligand in the apical position. {2,5-Bis[(diisopropylphosphanyl)methyl]pyrrolido-κ3 P,N,P′}dicarbonylchloridoiron(II), [Fe(C18H34NP2)Cl(CO)2] or [Fe(PNpyrP)Cl(CO)2], (III), is structurally similar to (I), but with the PMe3 ligand replaced by a second carbonyl ligand from the reaction of (II) with CO. The two carbonyl ligands are in a cis configuration, and there is positional disorder of the chloride and trans carbonyl ligands.

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Machado, I., M. Fernández, L. Becco, B. Garat, R. F. Brissos, N. Zabarska, P. Gamez, et al. "New metal complexes of NNO tridentate ligands: Effect of metal center and co-ligand on biological activity." Inorganica Chimica Acta 420 (August 2014): 39–46. http://dx.doi.org/10.1016/j.ica.2013.10.022.

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50

Onggo, D., DC Craig, AD Rae, and HA Goodwin. "Coordination of Hydrazone Derivatives of 2,2'-Bipyridine-6-carbaldehyde. Electronic and Structural Aspects of the Iron(II), Cobalt(II) and Nickel(II) Complexes." Australian Journal of Chemistry 44, no. 3 (1991): 331. http://dx.doi.org/10.1071/ch9910331.

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Iron(II), cobalt(II) and nickel(II) [MN6]2+ type complexes of the tridentate terimine ligands 2,2′-bipyridine-6-carbaldehyde phenylhydrazone ( bph ) and 2,2′-bipyridine-6-carbaldehyde 2-pyridylhydrazone ( bpyh ) have been prepared. The electronic spectrum of the [NiN6]2+ species indicates that the field strength of these ligands is near that at the iron(II) singlet/quintet crossover. Magnetic and Mossbauer spectral data reveal that salts of [Fe( bph )2]2+ are essentially low spin, while those of [Fe( bpyh )2]2+ are high spin. Salts of [Co( bph )2]2+ have strongly temperature-dependent magnetic moments which indicate a thermally induced doublet ↔ quartet spin transition in the metal atom. The structure of [Ni( bph )2][ClO4]2 reveals meridional coordination of the tridentate units, the azomethine nitrogen of the hydrazone moiety being bound to the metal atom. There is significant twisting (8.3°) of the two pyridyl rings in each ligand molecule about the interring bridge. The [NiN6]2+ fragment is tetragonally compressed and the mean Ni-N distance is 2.09 Ǻ. [Ni( bph )2][ClO4]2 is monoclinic, space group C2/c, Z = 4, a 23.949(3), b 7.868(1), c 21.303(3)Ǻ, β 117.95(2)°.

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Journal articles on the topic 'Tridentate Ligands - Metal Complexes'

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