Добірка наукової літератури з теми "Closo-Decaborate anions"

Here, we present composites and materials that can be prepared starting with boron hydride cluster compounds (decaborane, decahydro-closo-decaborate and dodecahydro-closo-dodecaborate anions and carboranes). Recent examples of their utilization as boron protective coatings including using them to synthesize boron carbide, boron nitride, metal borides, metal-containing composites, and neutron shielding materials are discussed. The data are generalized demonstrate the versatile application of materials based on boron cluster anions and carboranes in various fields.

A series of complexation reactions of silver(I) and copper(I) in the presence of a polyhedral weakly coordinating [B10Cl10]2− anion has been carried out. The effect of the solvent and the presence of Ph3P on the composition and structure of the reaction product were studied. Eight novel complexes were obtained and characterized by 11B Nuclear magnetic resonance, Infra-Red, and Raman spectroscopies as well as powder and single-crystal X-ray diffraction techniques. The [B10Cl10]2− anion demonstrated weaker coordinating ability towards coinage metals than [B10H10]2− at similar reaction conditions. The [B10Cl10]2− anion remains unreacted in the copper(I) complexation reaction, while in the absence of competing ligands, we obtained the first complexes containing decachloro-closo-decaborate anion directly coordinated by the metal atom. The bonding between metal atoms and the boron cluster anions was studied using the atomic Hirshfeld surfaces. Besides edge and face coordination of the polyhedral anion, this method allowed us to reveal the Ag–Ag bond in crystal of {Ag2(DMF)2[B10Cl10]}n, the presence of which was additionally supported by the Raman spectroscopy data.

A new series of compounds based on perbrominated disubstituted sulfonium derivatives of the closo-decaborate anion (n-Bu4N)[2-B10Br9SR2] (R = n-Pr, i-Pr, n-Bu, n-C8H17, n-C12H25, n-C18H37) was obtained, characterised by modern physicochemical methods of analysis. According to the results of an X-ray diffraction study, some of the anions and solvate molecules were disordered. The cations (n-Bu4N)+ and anions [2-B10Br9SR2]− were associated via C-H…Br and H…H contacts. In addition, Br…Br interactions between anions were revealed. The role of these contacts was analysed in terms of Hirshfeld surface analysis, QTAIM theory and the NCI method using quantum chemical calculations. An increase in the size of the alkyl R moiety led to significant strengthening of the total energy of H…H interactions. In the case of R = -n-C18H37, a parallel mutual orientation of alkyl moieties was established that was similar to the packing of salts of fatty acids. The nature of C-H…Br and Br…Br interionic interactions was found to be attractive, in contrast to the repulsive nature of intermolecular Br…Br interactions.

A comprehensive study focused on the preparation of disubstituted carboxonium derivatives of closo-decaborate anion [2,6-B10H8O2CC6H5]− was carried out. The proposed synthesis of the target product was based on the interaction between the anion [B10H11]− and benzoic acid C6H5COOH. It was shown that the formation of this product proceeds stepwise through the formation of a mono-substituted product [B10H9OC(OH)C6H5]−. In addition, an alternative one-step approach for obtaining the target derivative is postulated. The structure of tetrabutylammonium salts of carboxonium derivative ((C4H9)4N)[2,6-B10H8O2CC6H5] was established with the help of X-ray structure analysis. The reaction pathway for the formation of [2,6-B10H8O2CC6H5]− was investigated with the help of density functional theory (DFT) calculations. This process has an electrophile induced nucleophilic substitution (EINS) mechanism, and intermediate anionic species play a key role. Such intermediates have a structure in which one boron atom coordinates two hydrogen atoms. The regioselectivity for the process of formation for the 2,6-isomer was also proved by theoretical calculations. Generally, in the experimental part, the simple and available approach for producing disubstituted carboxonium derivative was introduced, and the mechanism of this process was investigated with the help of theoretical calculations. The proposed approach can be applicable for the preparation of a wide range of disubstituted derivatives of closo-borate anions.

Mixed-ligand lead(II) complexes with 2,2′-bipyridyl and [B10H9OH]2− or monosubstituted hydroxy-substituted closo-decaborate anions with a pendant hydroxy group, separated from the boron cage by an alkoxylic spacer of different lengths [B10H9O(CH2)xO(CH2)2OH]]2− (x = 2 or 5) have been synthesized. Compounds have been characterized by IR and multinuclear NMR spectroscopies. The structures of binuclear complex [Pb(bipy)2[B10H9OH]]2·CH3CN (1·CH3CN), mononuclear complex [Pb(bipy)2[B10H9O(CH2)2O(CH2)2OH]]·0.5bipy·CH3CN (2·0.5bipy·CH3CN), and polymeric complex [Pb(bipy)[B10H9O(CH2)5O(CH2)2OH]]n (3) have been determined by single-crystal X-ray diffraction. In all three compounds, the co-ordination polyhedra of lead(II) are formed by N atoms from two bipy molecules, O atoms of the substituent attached to the boron cage, and BH groups of the boron cage.

Abstract Thallium(I) decahydro-closo-decaborate Tl2[B10H10] and thallium(I) dodecahydro-closo-dodecaborate Tl2[B12H12] are readily available as microcrystalline powders from reactions of thallium(I) carbonate Tl2[CO3] with aqueous solutions of the respective free acid (H3O)2[B10H10] or (H3O)2[B12H12]. Tl2[B12H12] crystallizes with an anti-fluorite related structure (cubic, F m 3 ‾ $Fm\bar{3}$ , a = 1074.23(8) pm, Z = 4). Each Tl+ cation is coordinated by four icosahedral [B12H12]2– anions (d(B–B) = 180–181 pm) providing a twelvefold coordination sphere of hydrogen atoms (d(Tl–H) = 296 pm). Tl2[B10H10] crystallizes monoclinically in the space group P21/n with a = 704.03(5), b = 1111.45(8), c = 1281.16(9) pm and β = 94.912(3)° for Z = 4. The bicapped square antiprismatic [B10H10]2– anions (d(B–B) = 147–176 pm to the two apical boron atoms, d(B–B) = 161–199 pm within the corpus) again form distorted tetrahedra around the (Tl1)+, but square pyramids around the (Tl2)+ cations. Thus (Tl1)+ is coordinated by 12 hydrogen atoms (d(Tl1–H) = 275–315 pm), but (Tl2)+ only by 11 of them (d(Tl2–H) = 267–357 pm). Both compounds show a greenish-yellow photoluminescence caused by an interconfigurational 6sp –6s 2 emission (3Pn→1S0, n = 0–2) at the Tl+ cation.

Le développement d'une nouvelle classe de POM hybrides multifonctionnels, désignés sous le nom de "SiW10-B10-Ligand organique”, à partir du précurseur POM-Borate "SiW10-monoB10",a été étudié pour des applications biologiques.Ce dernier résulte de la réaction du groupe carbonyle de l'anion closo-décahydrodécaborate [B10H9CO]- avec l'un des deux groupes amine pendants du lien organique 3-(aminopropyl)triéthoxysilane, qui est attaché de manière covalente au polyoxométalate de type Keggin POM [SiW10O36]2-.L'objectif initiale de cette étude était d'aller plus loin en fonctionnalisant la deuxième fonction amine de SiW10-monoB10.Le composé mono-adduct "SiW10-monoB10" a d'abord été synthétisé avec une bonne pureté et en quantité suffisante,puis caractérisé par une spectrométrie RMN 1H-15N HMQC, ce qui a permis d'examiner la nature de la fonction amine libre et de montrer la présence d'une fraction d'amine non nulle qui ne serait pas impliquée dans l'interaction H-H avec le cluster de déca-borate.Malgré tous nos efforts et différentes stratégies étudiées, les études réalisées montrent que les interactions avec la partie POM et avec les groupements B-H sont préférentielles à la formation des liaisons covalentes espérées.Dans la partie suivante,nous nous sommes intéressés à d'autres POMs hybrides utilisés comme photo-amorceurs. Des dérivés à base d'anthracène, de benzophénone et d'anthraquinone ont été respectivement greffés de manière covalente sur la plateforme de polyoxométalate (POM) [Mo6O19]2-, donnant naissance à des complexes Lindqvist organo-imido: POM-imidoanthraquinone (POM-AQ), POM-imidoanthracène (POM-AC) et POM-imidobenzophénone (POM-AB). Il a été démontré que les photosystèmes combinant la N-méthyldiéthanolamine (MDEA) en tant que donneur d'électrons et ces hybrides POM favorisent la photopolymérisation radicalaire libre de dérivés de monomères acrylates sous irradiation dans le domaine visible,tandis que dans des conditions similaires, aucune polymérisation n'a été observée lorsque l'on ajoutait chacun des clusters d'hexamolybdate ou de l'entité organique seule avec la MDEA et les monomères acrylates. Grâce à la présence du POM,les revêtements préparés à l'aide du photosystème POM-AQ/MDEA/acrylate d'huile de soja époxydée présentent d'excellentes propriétés mécaniques,avec une très bonne flexibilité,et une résistance à la rupture fragile.Dans le dernier chapitre, la préparation de nouveaux complexes d'inclusion closo-borate/CD a été étudiée pour élaborer des systèmes suffisamment forts pour être envisagés pour des applications biologiques. Jouant sur le volume et la charge de [B10H10]2-,on a cherché à augmenter leur caractère chaotrope des clusters de bore et ainsi à augmenter leur affinité de liaison avec les CDs. L'encapsulation des anions [B10H9NCCH3]- et [B20H18]2- dans les CDs a été étudiée en deux parties distinctes.La spectrométrie de RMN ont montré la formation de complexes d'inclusion entre [B10H9NCCH3]- et [B20H18]2- et les beta- et gamma-CDs, tandis que des interactions plus faibles ont été observées avec la alpha-CD,pour laquelle les constantes de liaison ont été déterminées par RMN et ITC.Ces valeurs sont bien supérieures à celles obtenues lors de travaux antérieurs avec [B10H10]2- validant ainsi l'approche suivie dans ce travail de thèse.Une nouvelle approche en chimie du [B20H18]2- a également été étudiée à la fin du travail lié au processus d'échange hydrogène-deutérium en solution aqueuse de [B20H18]2-.La RMN 1H{11B} et 11B{1H} a mis en évidence des processus d'échange de deutérium-proton avec les protons des atomes de bore sur une période de temps en présence de dégradation. Il est intéressant de noter que, par le biais de la RMN de solutions [B20H18]2-/CD dans D2O,il a été démontré que les cyclodextrines beta et gamma protégeraient l'anion de la dégradation après 4 à 5 mois, ouvrant la voie à la conception de médicaments à base de bore offrant une stabilité accrue adaptée à une utilisation médicale
The development of a novel class of multifunctional POM hybrids, denoted as ″SiW10-B10-Organic ligand" starting from the POM-Borate precursor ″SiW10-monoB10", has been investigated for biological applications. The latter resulted from the reaction of the carbonyl group of closo-decahydrodecaborate anion [B10H9CO]- with one of the two pendant amine groups of the organic linker 3-(Aminopropyl)triethoxysilane (APTES), which is covalently attached to the POM Keggin-type polyoxometalate [SiW10O36]2-.Herein, we aimed to go further by functionalizing the second amine function of SiW10-monoB10.The mono-adduct ″SiW10-monoB10” compound was firstly synthesized with good purity and in sufficient quantities, then characterized by atypical 1H-15N HMQC NMR, which allowed the examination of the nature of the free amine function and showed the presence of non-zero amine fraction that would not be involved in the H-H interaction with the decaborate cluster. Consequently, the possibility of new functional groups on this free amino arm of SiW10-monoB10 adduct was tested and followed through 1H and 11B NMR. Despite our best efforts and the various strategies, we have investigated, the studies carried out show that interactions with the POM part and with B-H groups are preferential to the formation of the covalent bonds we had hoped for.In the following section, we turned our attention to other hybrid POMs used as photoinitiators. Anthracene-, benzophenone- and anthraquinone-based derivatives were respectively covalently grafted onto the polyoxometalate (POM) platform [Mo6O19]2-, giving rise to highly colored organo-imido Lindqvist complexes: POM-imidoanthraquinone (POM-AQ), POM-imidoanthracene (POM-AC), and POM-imidobenzophenone (POM-AB). It has been evidenced that photosystems combining N-methyldiethanolamine (MDEA) as electron donor and these hybrid POMs promote free-radical photopolymerization of acrylate monomer derivatives under irradiation in the visible range, while in similar conditions, no polymerization was observed considering when adding each of the hexamolybdate cluster or the organic entity alone with the MDEA and acrylate monomers. Such organo-imido Lindqvist species can represent new, easy-to-synthesize, efficient visible-light photoinitiators. Moreover, due to the presence of the POM, coatings prepared using the POM-AQ/MDEA/Soybean oil epoxidized acrylate photosystem exhibit excellent mechanical properties, with very good flexibility, resistance to brittle fracture, and adherence to the steel.In the last chapter, the preparation of new closo-borate/CD inclusion complexes has been studied to elaborate systems strong enough to be considered for biological application. Playing on the volume and charge of [B10H10]2- was set out to increase their chaotropic character and thus enhance their binding affinity to cyclodextrins. The encapsulation of [B10H9NCCH3]- and [B20H18]2- anions within cyclodextrins has been investigated in two different parts. ESI-MS and NMR evidenced the formation of inclusion complexes between the borate compounds and beta- and gamma-CDs, while weaker interactions are evidenced with alpha-CD, for which the binding constants were determined by NMR and ITC. These constant values are much higher than those obtained in previous work with [B10H10]2- thus validating the approach followed in this thesis work.A new approach in [B20H18]2- chemistry has also been studied at the end of the work related to the Hydrogen-Deuterium exchange process in [B20H18]2- aqueous solution.1H{11B} and 11B{1H} NMR evidenced selective deuterium-proton exchange processes with the protons of equatorial Boron atoms over a period of time with the presence of degradation. Interestingly, it has been shown through NMR of [B20H18]2-/CD solutions in D2O that beta- and gamma-CDs would protect the anion from degradation after 4-5 months, opening the route for designing Boron-based drugs with enhanced stability suitable for medical use