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Autore: Grafiati

Pubblicato: 7 luglio 2024

Ultima modifica: 7 luglio 2024

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1

Zhao, Lili, Chaoqun Chai, Wolfgang Petz e Gernot Frenking. "Carbones and Carbon Atom as Ligands in Transition Metal Complexes". Molecules 25, n. 21 (26 ottobre 2020): 4943. http://dx.doi.org/10.3390/molecules25214943.

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This review summarizes experimental and theoretical studies of transition metal complexes with two types of novel metal-carbon bonds. One type features complexes with carbones CL2 as ligands, where the carbon(0) atom has two electron lone pairs which engage in double (σ and π) donation to the metal atom [M]⇇CL2. The second part of this review reports complexes which have a neutral carbon atom C as ligand. Carbido complexes with naked carbon atoms may be considered as endpoint of the series [M]-CR3 → [M]-CR2 → [M]-CR → [M]-C. This review includes some work on uranium and cerium complexes, but it does not present a complete coverage of actinide and lanthanide complexes with carbone or carbide ligands.

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2

Liénard, Amandine, e Gilles Colinet. "Transfert en cadmium et zinc vers l’orge de printemps en sols contaminés et non contaminés de Belgique : évaluation et prédiction". Cahiers Agricultures 27, n. 2 (28 febbraio 2018): 25002. http://dx.doi.org/10.1051/cagri/2018008.

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En Région wallonne, des sols agricoles situés à proximité d’anciens sites de traitements de minerais ont été impactés par des retombées atmosphériques contaminées en cadmium (Cd), plomb (Pb) et zinc (Zn). Afin d’étudier l’impact de ces contaminations sur la qualité des productions agricoles, une étude du transfert en Cd et Zn du sol vers l’orge de printemps (Hordeum vulgare L.) a été réalisée sur une de ces zones contaminées. Dix-huit prélèvements d’orges ont été effectués en zone contaminée, 10 autres en zone témoin non contaminée et chacun d’eux a été subdivisé en trois sous-échantillons (tige, épi et grain). Un prélèvement a été réalisé dans l’horizon de surface du sol (de 0 à 20 cm) à l’emplacement de chaque prélèvement de plantes. Les concentrations disponibles et pseudo-totales en éléments traces et majeurs ainsi que pHeau, pHKCl, carbone organique total et azote total ont été mesurés sur les échantillons de sols. Les concentrations en Cd et Zn ont été dosées dans les grains, les épis et les tiges. Les concentrations en Cd et Zn mesurées dans les plantes récoltées sur la zone contaminée sont de 2 à 9 fois supérieures à celles mesurées dans les orges témoins. Il existe peu de relations entre la concentration en cadmium dans les grains (CdGrain), la concentration en zinc dans les grains (ZnGrain) et les propriétés des sols à l’exception des teneurs en Cd et Zn du sol. Une analyse Cate-Nelson a permis d’estimer CdGrain à 0,027 mg de Cd/kg matière sèche (MS) pour des teneurs pseudo-totales en Cd dans le sol allant de 0 à 1,23 mg/kg, et à 0,118 mg de Cd/kg de MS pour des teneurs pseudo-totales en Cd dans le sol allant de 1,24 à 6,87 mg/kg. ZnGrain est estimé à 19,2 mg/kg de MS pour des teneurs pseudo-totales de Zn dans le sol allant de 0 à 131 mg/kg, et à 40 mg/kg de MS pour des teneurs pseudo-totales de Zn dans le sol allant de 132 à 570 mg/kg. Une estimation du transfert en Cd et Zn reste toutefois complexe dans ces sols multicontaminés.

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3

Chaton, Corinne, e Coline Metta-Versmessen. "Le contrat carbone pour différences, un outil adapté pour la décarbonation de l’hydrogène ?" Revue économique Vol. 74, n. 5 (4 gennaio 2024): 705–37. http://dx.doi.org/10.3917/reco.745.0705.

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Le marché carbone EU-ETS n’est pas suffisant pour décarboner rapidement les secteurs où les technologies bas-carbone sont trop coûteuses par rapport aux technologies existantes. Pour y remédier, cette étude caractérise un « contrat carbone pour différences » (CCfD). Il s’agit d’un instrument qui garantit aux producteurs bas-carbone un prix carbone suffisant pour assurer la compétitivité de leur technologie par rapport à celles émettrices. Nous proposons une méthodologie pour concevoir les CCfD selon la région et le secteur d’application. Nous nous concentrons sur le développement de l’hydrogène par électrolyse comme alternative au vaporeformage du méthane. Du fait du double impact du prix carbone, nous soutenons que ce CCfD est un contrat complexe et qu’il devrait être défini pour des zones ayant un mix électrique homogène . Classification JEL : D47, H23, O38, Q48, Q52.

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4

BIDDULPH, George Elliot, Yannick Enock BOCKO, Pierre BOLA, Bart CREZEE, Greta DARGIE, Ovide EMBA, Selena GEORGIOU et al. "Connaissances actuelles et orientations futures des recherches sur le complexe de tourbières de la Cuvette centrale du Congo". BOIS & FORETS DES TROPIQUES 355 (1 marzo 2023): 73–86. http://dx.doi.org/10.19182/bft2023.355.a37152.

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La Cuvette centrale est le plus vaste complexe de tourbières tropicales au monde, qui s'étend sur environ 145 000 km2 en République du Congo et en République démocratique du Congo. Ce complexe stocke environ 30,6 Pg C, soit l'équivalent de trois années d'émissions mondiales de dioxyde de carbone, et représente désormais le premier site Ramsar transnational. Malgré sa taille et son importance mondiale en tant que puits de carbone, les aspects clés de son écologie et de son histoire, notamment sa formation, l'ampleur des flux de gaz à effet de serre, sa biodiversité et l'histoire de l'activité humaine, demeurent relativement peu connus. Nous synthétisons ici les connaissances disponibles sur la Cuvette centrale, en identifiant des domaines clés pour la poursuite des recherches. Enfin, nous examinons le potentiel des modèles mathématiques pour évaluer les trajectoires futures des tourbières en termes d’impacts prévisibles de l'exploitation de ressources et du changement climatique.

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5

Frenking, Gernot, e Ralf Tonner. "Divalent carbon(0) compounds". Pure and Applied Chemistry 81, n. 4 (1 gennaio 2009): 597–614. http://dx.doi.org/10.1351/pac-con-08-11-03.

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Quantum chemical studies show that there is a class of carbon compounds with the general formular CL2 where the carbon atom retains its four valence electrons as two lone pairs. The C-L bonds come from L → C donor-acceptor interactions where L is a strong σ-donor. Divalent C(0) compounds (carbones) are conceptually different from divalent C(II) compounds (carbenes) and tetravalent carbon compounds, but the bonding situation in a real molecule may be intermediate between the three archetypes. There are molecules like tetraaminoallenes which may be described in terms of two double bonds (R2N)2C=C=C(NR2)2 where the extraordinary donor strength of the dicoordinated carbon atom comes only to the fore through the interactions with protons and Lewis acids. They may be considered as "hidden divalent C(0) compounds". The donor strength of divalent C(0) molecules has been investigated by calculations of the binding energies with protons and with main-group Lewis acids and the bond dissociation energies (BDEs) of transition-metal complexes.

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6

Frański, Rafał, Błażej Gierczyk, Grzegorz Schroeder, Stefan Pieper, Andreas Springer e Michael Linscheid. "Electrospray ionization mass spectrometric study of mercury complexes of N-heterocyclic carbenes derived from 1,2,4-triazolium salt precursors". Open Chemistry 5, n. 1 (1 marzo 2007): 316–29. http://dx.doi.org/10.2478/s11532-006-0050-0.

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AbstractBy mixing 1,2,4-triazolium salts (precursors of N-heterocyclic carbenes 1–6) with mercury acetate, a number of complexes have been obtained under electrospray ionization condition. Carbenes 1 and 2 contain one carbene center; therefore, they are able to bond only one mercury cation. Carbenes 3–5 contain two carbene centers; therefore, they can bond two mercury cations. Mercury complexes of 1–5 always contain an acetate anion attached to a mercury cation. Carbene 6 also contains two carbene centers; however, its structure allows formation of a complex containing mercury bonded simultaneously to both centers, therefore, the complex that does not contain an acetate anion. The MS/MS spectra taken for complexes of carbenes 1–5 have shown formation of a cation corresponding to N1 substituent (adamantyl or benzyl), and those of complexes of carbenes 3–5 (doubly charged ions) have also shown the respective complementary partner ions. Mercury complex of 2 has yielded some other interesting fragmentation pathways, e.g. a loss of the HHgOOCCH3 molecule. The fragmentation pathway of the mercury complexes of 6 was found to be complicated.

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7

Wernert, Carole. "Les héritages d’une trajectoire énergétique dans un ancien bassin houiller : le cas complexe d’une transition à Sarrebruck". Réactions d’épidémie, n. 2 (1 novembre 2020): 127–47. http://dx.doi.org/10.57086/rrs.144.

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Cet article vise à contribuer à la déconstruction de la vision monolithique du processus de transition énergétique bas carbone à travers la notion de trajectoire énergétique. L’objectif principal est d’identifier les différents marqueurs susceptibles d’enclencher ou de ralentir la transition bas carbone à travers une analyse historique, multiscalaire et politisée de la trajectoire énergétique de la ville allemande de Sarrebruck. Située au cœur du bassin houiller sarro-lorrain (concurrent de celui de la Ruhr), la ville a longtemps été dépendante d’un mix énergétique fondé sur le charbon local. Mais au tournant des années 1990, la ville et son entre- prise municipale de l’énergie (Stadtwerk) se sont positionnées en tant que pionnières dans l’élaboration de programmes d’énergies renouvelables et de sobriété énergétique. La trajectoire énergétique de la ville de Sarrebruck montre alors un processus de transition bas carbone non linéaire, à séquences alternées.

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8

Ning, Yalan, Robert D. J. .Froese, Peter Margl, Edward L. Lee, SonBinh T. Nguyen, Thomas H. Peterson, Nicole Wagner, Charlotte L. Stern e Amy A. Sarjeant. "Efficient Carbene and Carbyne Formation in Molybdenum(0) and Tungsten(0) Dinitrogen Complexes". Organometallics 33, n. 5 (21 febbraio 2014): 1120–25. http://dx.doi.org/10.1021/om4006214.

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9

Gabor, Barbara, Carl Krüger, Bernd Marczinke, Richard Mynott e Günther Wilke. "Nickel(0)-Carbene Complexes". Angewandte Chemie International Edition in English 30, n. 12 (dicembre 1991): 1666–68. http://dx.doi.org/10.1002/anie.199116661.

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10

Filippou, Alexander Constantin, e Walter Grünleitner. "Säure-induzierte CC-Kupplung von Isocyanid-Liganden in homoleptischen Alkylisocyanid-Komplexen von Mo(0) und W(0) / Acid-Induced CC-Coupling of Isocyanide Ligands in Homoleptic Alkylisocyanide Complexes of Mo(0) and W(0)". Zeitschrift für Naturforschung B 46, n. 2 (1 febbraio 1991): 216–30. http://dx.doi.org/10.1515/znb-1991-0216.

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Reactions of the electron-rich, homoleptic alkylisocyanide complexes M(R N C)6 (1a-2b) (1: M = Mo, 2: M = W; a: R = Et, b: R = tBu) with electrophiles have been studied. A coupling of two isocyanide ligands to a complexed alkyne ligand is observed, when M(R N C)6 is treated with two equivalents of HX(X = Br, I) and leads to the bis(alkylamino)acetylene complexes [X (R N C )4M[η2-R(H)NC ≡ CN(H)R]]X (3a′-4b″) (3: M = Mo, 4: M = W). Treatment of W (EtNC)6 (2a) and W (tBuNC)6 (2b) with one equivalent of Me3SiOTf results in the quantitative formation of the aminocarbyne complexes [(EtNC)5W ≡ CN (SiMe3)Et]OTf (6c) and [(tBuNC)5W ≡ C N (SiMe3)tBu]OTf (6d), respectively. In comparison, an equilibrium between W(tBuNC)6 (2b) and the aminocarbyne complex [(tBuNC)5W ≡ C N (SiMe3)tBu]Cl (6e) is found, when 2b is treated with Me3SiCl. The compounds 6c and 6d are structurally related to the aminocarbyne complexes [(EtNC)5M ≡ C N E t2]BF4 (5a: M = Mo, 6a: M = W) and [(tBuNC)5W ≡ C N (Et)Bu]BF4 (6b), which are obtained from ethylation of M (EtNC)6 (1a, 2a) and W (tBuNC)6 (2b) with Et3OBF4. 5a and 6a undergo with HI a carbyne-isocyanide coupling reaction to give the alkyne complexes [I(EtNC)4Mo[η2-Et2NC≡CN(H)Et]]BF4 (7a) and [I(EtNC)4W[η2-Et2NC≡CN(H)Et]]BF4 (8a), respectively. Similar reactivity is exhibited by 6b, which yields with HI the alkyne complex [I(tBuNC)4W[η2-tBu(Et)N C ≡ C N (H)tBu]]BF4 (8b). The reported transformation of a complexed isocyanide to an aminocarbyne and the acid-induced aminocarbyne-isocyanide coupling reaction are experimentally verified to be important steps in the reductive coupling of isocyanide ligands in [M(RNC)6X]+-complexes yielding the bis(alkylamino)acetylene compounds [X(R N C)4M[η2-R (H )N C ≡ C N (H )R ]]+.

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11

Hu, Chaopeng, Xin-Feng Wang, Jiancheng Li, Xiao-Yong Chang e Liu Leo Liu. "A stable rhodium-coordinated carbene with a σ ⁰ π ² electronic configuration". Science 383, n. 6678 (5 gennaio 2024): 81–85. http://dx.doi.org/10.1126/science.adk6533.

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Isolable singlet carbenes have universally adopted a σ 2 π 0 electronic state, making them σ-donors and π-acceptors. We present a rhodium-coordinated, cationic cyclic diphosphinocarbene with a σ 0 π 2 ground state configuration. Nuclear magnetic resonance spectroscopy studies show a carbene carbon chemical shift below −30.0 parts per million. X-ray crystallography reveals a planar RhP 2 C configuration. Quantum chemical calculations rationalize how σ-electron delocalization/donation and π-electron negative hyperconjugation together stabilize the formally vacant σ orbital and the filled π orbital at the carbene center. In contrast to traditional carbene counterparts this carbene can undergo synthetic transformations with both a Lewis base and a silver salt, producing a Lewis acid/base adduct and a silver π-complex, respectively. Exhibiting ambiphilic reactivity, it can also form a ketenimine through reaction with an isocyanide.

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12

Klein, Hans-Friedrich, Goetz Lull, Birgit Rodenhäuser, Gerhard Cordier e Helmut Paulus. "Monoolefincobalt(0)-Komplexe / Monoolefincobalt(0) Complexes". Zeitschrift für Naturforschung B 43, n. 10 (1 ottobre 1988): 1256–62. http://dx.doi.org/10.1515/znb-1988-1008.

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Mononuclear cobalt(o) complexes containing olefin and trimethylphosphane ligands Co(olefin)(PMe3)3 (olefin = C2H4 (1), C3H6 (2), cyclopentene (3), trans-1,2-diphenylethene (4), tetrafluorobenzo-bicyclo-(2.2.2)-octadiene (5)), are obtained from CoCl2 by reaction with magnesium in the presence of the ligands or by substitution of 3 with olefin. X-ray crystal structure determinations of 4 and 5 show a distorted tetrahedral arrangement of ligands around the cobalt atom. Chemical and spectroscopic properties are consistent with a paramagnetic valence state of the compounds in solution. By reaction with carbon monoxide a dicobalt complex is formed, while azobenzene gives paramagnetic Co(N2Ph2)(PMe3)2.

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13

Schubert, Ulrich, Wolfgang Hepp e Johannes Muller. "Silicon-containing carbene complexes. 6. Stable 16-electron carbonyl carbene complexes of tungsten(0), molybdenum(0), and chromium(0)". Organometallics 5, n. 1 (gennaio 1986): 173–75. http://dx.doi.org/10.1021/om00132a031.

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14

Arduengo, Anthony J., Siegfried F. Gamper, Joseph C. Calabrese e Fredric Davidson. "Low-Coordinate Carbene Complexes of Nickel(0) and Platinum(0)". Journal of the American Chemical Society 116, n. 10 (maggio 1994): 4391–94. http://dx.doi.org/10.1021/ja00089a029.

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15

Jutand, Anny, Julien Pytkowicz, Sylvain Roland e Pierre Mangeney. "Mechanism of the oxidative addition of aryl halides to bis-carbene palladium(0) complexes". Pure and Applied Chemistry 82, n. 7 (4 maggio 2010): 1393–402. http://dx.doi.org/10.1351/pac-con-09-09-22.

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Bis-N-heterocyclic carbenes Pd0 complexes, Pd0(NHC)2, are efficient catalysts in Heck reactions performed with aryl bromides or chlorides. The Pd0(NHC)2 that are not stable are generated in situ from PdII precursors PdY2(NHC)2 (Y = halides) after a chemical reduction. The latter procedure can be mimicked by an electrochemical reduction. The transient Pd0(NHCBn)2 is generated by electrochemical reduction of PdY2(NHCBn)2, and its reactivity in oxidative addition to aryl bromides and chlorides is characterized by the same electrochemical technique with the determination of the rate constants. Pd0(NHCBn)2 is found to be more reactive than the mixed complex Pd0(NHCBn)(PPh3). Both are the reactive species in an associative mechanism. Comparison with the isolated Pd0(NHCtBu)2 reveals that Pd0(NHCBn)2 is more reactive than Pd0(NHCtBu)2 even if the latter reacts via the mono-carbene Pd0(NHCtBu) in a dissociative mechanism. This suggests that the formation of mono-carbene Pd0(NHC) is not a guarantee for a fast oxidative addition because it is always generated at low concentration in its equilibrium with the related nonreactive bis-carbene Pd0(NHC)2.

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16

Sierra, Miguel A., Juan C. del Amo, Marı́a J. Mancheño e Mar Gómez-Gallego. "Low temperature carbene transfer from alkoxychromium(0) (Fischer) carbene complexes". Tetrahedron Letters 42, n. 32 (agosto 2001): 5435–38. http://dx.doi.org/10.1016/s0040-4039(01)01082-6.

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17

Hahn, F. Ekkehardt, Nicole Meier e Tania Pape. "Synthesis of a Benzothiazol-2-ylidene Complex of Tungsten(0) and Transfer of the Ylidene Ligand to Rhodium(I)". Zeitschrift für Naturforschung B 61, n. 7 (1 luglio 2006): 820–24. http://dx.doi.org/10.1515/znb-2006-0708.

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2-Lithiobenzothiazole reacts with freshly generated [W(CO)5(THF)] to give the anionic ylidene complex (1). Treatment of 1 with allyl bromide yields complex [W(CO)5(1-allylbenzothiazolin-2- ylidene)] (2) while the reaction in wet CH2Cl2 leads to the formation of a mixture of 2 (major) and [W(CO)5(1-H-benzothiazolin-2-ylidene)] (3) (minor). Complex 2 reacts in a transmetallation reaction with [Rh(coe)2(μ-Cl)]2 (coe = cyclooctone) to give the dicarbene complex [Rh(Cl)(η1- NHC)(η2-NHC)] (NHC = 1-allylbenzothiazolin-2-ylidene) with one carbene ligand coordinated via the C2 carbon atom and the other one coordinating with both the C2 carbon atom and the allyl group.

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18

van Vliet, Gijs. "Stabiliseren bij complexe PTSS?" GZ - Psychologie 11, n. 5 (ottobre 2019): 28–31. http://dx.doi.org/10.1007/s41480-019-0060-0.

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19

Fernández, Israel, Miguel A. Sierra, María José Mancheño, Mar Gómez-Gallego e Susagna Ricart. "Synthesis of Cyclophanic Chromium(0) Bis(carbene) Complexes". Organometallics 20, n. 21 (ottobre 2001): 4304–6. http://dx.doi.org/10.1021/om010561e.

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Mouriquand, P., e I. Vidal. "Complexe exstrophie épispade (CEE)". EMC - Urologie 5, n. 1 (febbraio 2012): 1–18. http://dx.doi.org/10.1016/s1762-0953(12)33127-0.

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Jaeger, Monika, Rüdiger Stumpf, Carsten Troll e Helmut Fischer. "Novel hepta-coordinated molybdenum(ii) and tungsten(ii) carbene complexes by oxidative decarbonylation of Mo(0) and W(0) carbene complexes". Chemical Communications, n. 11 (2000): 931–32. http://dx.doi.org/10.1039/b002228o.

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Mour, İzzet A., Saim Ozkar e Cornelius G. Kreiter. "Synthesis and Spectroscopic Studies of Pentacarbonylfumaronitrile-chromium(0), -molybdenum(0), and -tungsten(0)". Zeitschrift für Naturforschung B 49, n. 8 (1 agosto 1994): 1059–62. http://dx.doi.org/10.1515/znb-1994-0808.

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Photolysis of hexacarbonyl-chromium(0), -molybdenum(0), and -tungsten(0) in presence of fumaronitrile yields at room temperature pentacarbonyl-fumaronitrile-chromium(0) (1), - molybdenum(0) (2), and -tungsten(0) (3). The complexes were purified by crystallization and characterized by IR and 13C-NMR spectroscopy. The fumaronitrile ligand is bonded to the M(CO)5 moiety by one nitrile nitrogen atom rather than by the carbon-carbon double bond. In toluene 2 dissociates into fumaronitrile and pentacarbonyl-molybdenum(0), which is stabilized by the solvent. Fumaronitrile and solvated pentacarbonyl-molybdenum(0) exist in solution together with 2 in an equilibrium which lies in favour of the former species.

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Jansen van Rensburg, Armand, Marilé Landman, Deidré van der Westhuizen, Marrigje M. Conradie e Jeanet Conradie. "Electrochemistry of Triphenylarsine-substituted Tungsten(0) Fischer carbene complexes". Electrochimica Acta 186 (dicembre 2015): 321–27. http://dx.doi.org/10.1016/j.electacta.2015.11.001.

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Sierra, Miguel A., Juan C. del Amo, Maria J. Mancheno e Mar Gomez-Gallego. "ChemInform Abstract: Low Temperature Carbene Transfer from Alkoxychromium(0) (Fischer) Carbene Complexes." ChemInform 32, n. 44 (24 maggio 2010): no. http://dx.doi.org/10.1002/chin.200144078.

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Jonas, KOALA, KAGAMBEGA O. Raymond e SANOU Lassina. "Distribution des stocks de carbone du sol et de la biomasse racinaire dans un parc agroforestier à Prosopis africana (Guill., et Rich.) Taub au Burkina Faso, Afrique de l’Ouest". Journal of Applied Biosciences 160 (30 aprile 2021): 16482–94. http://dx.doi.org/10.35759/jabs.160.5.

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Objectif : Cette présente étude visait à déterminer la distribution verticale des stocks de carbone organique du sol et de la biomasse racinaire dans un parc agroforestière à Prosopis africana (Guill., et Rich.) Taub au Burkina Faso. Méthodologie et Résultats : L’étude a été menée à Saria sur un dispositif factoriel avec 3 répétitions. L’échantillonnage des racines et du sol a été fait par l’extraction de monolithes sur 5 couches à une profondeur de 150 cm. Les résultats montrent que la profondeur a influencé les stocks de carbone. La couche 0-50 cm renferme 91% du stock total de carbone de la biomasse racinaire. Les stocks de Carbone Organique du Sol (COS) le plus élevé a été enregistré dans la couche 80-120 cm (26,59±7,94 tC ha-1), contre 8,74±6,05 tC ha-1 dans la couche 0-20 cm. Conclusion et implication des résultats : Les résultats montrent que les parcs agroforestiers étudiés ont un fort potentiel de séquestration de carbone. Cependant, les éventuels projets de carbone dans les parcs agroforestiers devront se focaliser sur la biomasse végétale aérienne et souterraine car le carbone organique du sol parait ne pas être influencé par les différents aménagements. Aussi pour une bonne gestion de ces stocks de carbone, des études complémentaires doivent être menées en vue de comprendre le cycle de de renouvellement des racines fines des parcs agroforestiers afin de de mesurer les flux de carbone organique du sol dans les parcs agroforestiers. Mots clés : Carbone organique du sol; Parc agroforestier, Prosopis africana, séquestration de carbone ; Biomasse racinaire 16482 Koala et al., J. Appl. Biosci. Vol.160 :2021 Distribution des stocks de carbone du sol et de la biomasse racinaire dans un parc agroforestier à Prosopis africana (Guill., et Rich.) Taub au Burkina Faso, Afrique de l’Ouest Distribution of carbon stocks from soil and root biomass in Prosopis africana (Guill., And Rich.) Taub agroforestry parkland in Burkina Faso, West Africa. ABSTRACT Objectives The aim of this study was to determine soil organic carbon stocks and root biomass carbon vertical distribution in an agroforestry parkland of Prosopis africana (Guill., And Rich.) Taub in Burkina Faso. Methodology and Results: The study was carried out in Saria on factorial design with 3 replicates. Root and soil sampling was done by extracting monoliths in 5-layer up to 150 cm depth. Results show that depth influenced carbon stocks. 0-50 cm layer contains 91% of root biomass total carbon stock. Highest soil Organic Carbon (SOC) stocks were recorded in 80-120 cm layer (26.59 ± 7.94 tC ha-1), compared to 8.74 ± 6.05 tC ha-1 in 0-20 cm layer. Conclusions and application of findings: Our results show that agroforestry parklands have a high carbon sequestration potential. However, any carbon projects in agroforestry parklands have to focus on trees above-ground and below-ground biomass because soil organic carbon does not influenced by management. Also for good management of these carbon stocks, additional studies must be carried out in order to understand the renewal cycle of fine roots in agroforestry parks in order to measure organic carbon flow from soil in agroforestry parklands. Keywords: Soil organic carbon; Agroforestry parklands, Prosopis africana, carbon sequestration; Root biomass INTRODUCTION L’agroforesterie est un système d’utilisation des terres traditionnel qui est toujours utilisé de nos jours par les populations (Santoro et al., 2020). Elle est considérée comme un système durable car contribuant à lutter contre la dégradation des terres. Sa contribution à l’amélioration à la productivité de l’agriculture est bien reconnue de nos jours (Montagnini and Nair, 2004). L’amélioration de la productivité est due à l’augmentation de la matière organique et au recyclage des éléments

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Liu, Yang, Jun Cheng e Liang Deng. "Three-Coordinate Formal Cobalt(0), Iron(0), and Manganese(0) Complexes with Persistent Carbene and Alkene Ligation". Accounts of Chemical Research 53, n. 1 (27 dicembre 2019): 244–54. http://dx.doi.org/10.1021/acs.accounts.9b00492.

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Fränkel, Robert, Ulrich Kernbach, Maria Bakola-Christianopoulou, Ulrike Plaia, Max Suter, Werner Ponikwar, Heinrich Nöth, Claude Moinet e Wolf Peter Fehlhammer. "Homoleptic carbene complexes". Journal of Organometallic Chemistry 617-618 (gennaio 2001): 530–45. http://dx.doi.org/10.1016/s0022-328x(00)00713-0.

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Ducassé, J. L., B. Joly, G. Baillé e P. Sanchez. "Intoxication collective au monoxyde de carbone". Réanimation Urgences 4, n. 4 (gennaio 1995): 365–69. http://dx.doi.org/10.1016/s1164-6756(05)80676-0.

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29

Baeza, Beatriz, Luis Casarrubios, Mar Gómez-Gallego, Miguel A. Sierra e Montserrat Oliván. "Multicomponent Synthesis of Pyran-2-ylidene Chromium(0) and Tungsten(0) Fischer Carbene Complexes". Organometallics 29, n. 7 (12 aprile 2010): 1607–11. http://dx.doi.org/10.1021/om9009558.

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30

Weber, Jaques, E. Peter Kundig, Annick Goursot e Edouard Penigault. "The electronic structures of bis(η6-benzene)- and bis(η6-naphthalene)chromium(0)". Canadian Journal of Chemistry 63, n. 7 (1 luglio 1985): 1734–40. http://dx.doi.org/10.1139/v85-291.

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SCF MS Xα molecular orbital calculations are reported for the bis(η6-benzene)- and bis(η6-naphthalene)chromium(0) complexes. The bonding may be essentially discussed in terms of the covalent interactions between the metal 3d and ligand π and π* orbitals. The different charges on chromium atom in the two systems are explained by the different balances between ligand-to-metal (bonding) and metal-to-ligand (back-bonding) electron donations. Some resemblances are found between the electronic structures of the two compounds and it is possible to correlate to a large extent the energy levels of their molecular orbitals. However, a shift towards lower values is predicted for the energy levels of the naphthalene complex, together with a large disruption of all the virtual π* and 3d* levels. This would undoubtedly favor nucleophilic attack followed by metal–ring or carbon–carbon bond cleavage, in agreement with the extreme lability of the coordinated arene rings observed in this complex.

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31

Schers, H. J., e M. Nieuwboer. "Eerstelijns innovaties in de complexe ouderenzorg". Bijblijven 2010, n. 8 (dicembre 2010): 26–32. http://dx.doi.org/10.1007/s12414-010-0114-0.

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32

Bohanna, Cristina, Miguel A. Esteruelas, Fernando J. Lahoz, Enrique Onate, Luis A. Oro e Eduardo Sola. "Synthesis of Butadiene-Osmium(0) and -Ruthenium(0) Complexes by Reductive Carbon-Carbon Coupling of Two Alkenyl Fragments". Organometallics 14, n. 10 (ottobre 1995): 4825–31. http://dx.doi.org/10.1021/om00010a051.

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33

Markó, István E., Sébastien Stérin, Olivier Buisine, Gérard Mignani, Paul Branlard, Bernard Tinant e Jean-Paul Declercq. "Selective and Efficient Platinum(0)-Carbene Complexes As Hydrosilylation Catalysts". Science 298, n. 5591 (4 ottobre 2002): 204–6. http://dx.doi.org/10.1126/science.1073338.

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34

De Bo, Guillaume, Guillaume Berthon-Gelloz, Bernard Tinant e István E. Markó. "Hydrosilylation of Alkynes Mediated byN-Heterocyclic Carbene Platinum(0) Complexes". Organometallics 25, n. 8 (aprile 2006): 1881–90. http://dx.doi.org/10.1021/om050866j.

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35

Jansen van Rensburg, Armand, Marilé Landman, Marrigje M. Conradie, Elizabeth Erasmus e Jeanet Conradie. "Electrochemistry of triphenylstibine-functionalized Fischer carbene complexes of Molybdenum(0)". Electrochimica Acta 246 (agosto 2017): 897–907. http://dx.doi.org/10.1016/j.electacta.2017.06.103.

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36

Lage, Marta L, Israel Fernández, María J Mancheño, Mar Gómez-Gallego e Miguel A Sierra. "Metal-Tuned Photochemistry of Metallocene-Substituted Chromium(0)-Carbene Complexes". Chemistry - A European Journal 15, n. 3 (5 gennaio 2009): 593–96. http://dx.doi.org/10.1002/chem.200802005.

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37

Chatrenet, Yves. "Lombalgies : l’indispensable réharmonisation du complexe musculaire". Kinésithérapie, la Revue 11, n. 109-110 (gennaio 2011): 29–31. http://dx.doi.org/10.1016/s1779-0123(11)75010-0.

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38

Deroin, Philippe. "Un marché à la dynamique complexe". Biofutur 1998, n. 184 (dicembre 1998): 80–81. http://dx.doi.org/10.1016/s0294-3506(99)80018-0.

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39

Wang, Zhe, Shenyu Li, Wei Jie Teo, Yu Ting Poh, Jin Zhao e T. S. Andy Hor. "Molybdenum (0) and tungsten (0) carbonyl N-heterocyclic carbene complexes as catalyst for olefin epoxidation". Journal of Organometallic Chemistry 775 (gennaio 2015): 188–94. http://dx.doi.org/10.1016/j.jorganchem.2014.07.009.

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40

BALDOLI, C., P. DEL BUTTERO, E. LICANDRO, S. MAIORANA e A. PAPAGNI. "ChemInform Abstract: Chemoselective Oxidation of ((Arylthioalkylpyrrolidino)carbene) chromium(0) Pentacarbonyl Complexes: Synthesis of (Arylsulfinyl and Arylsulfonylalkylpyrrolidino)carbene Complexes." ChemInform 26, n. 46 (17 agosto 2010): no. http://dx.doi.org/10.1002/chin.199546200.

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41

Baeza, Beatriz, Luis Casarrubios e Miguel A. Sierra. "A Click Approach to Polymetallic Chromium(0) and Tungsten(0) Fischer-Carbene Complexes and Their Use in the Synthesis of Functionalized Polymetallic MetalCarbene Complexes". Chemistry - A European Journal 19, n. 4 (30 novembre 2012): 1429–35. http://dx.doi.org/10.1002/chem.201202328.

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42

St-Hilaire, A., D. Caissie, N. El-Jabi e G. Morin. "Évaluation de l'applicabilité d'une méthode statistique aux variations saisonnières des relations concentration-débit sur un petit cours d'eau". Revue des sciences de l'eau 11, n. 2 (12 aprile 2005): 175–90. http://dx.doi.org/10.7202/705302ar.

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Abstract (sommario):

Les paramètres chimiques jouent un rôle important dans l'équilibre des écosystèmes aquatiques. De nombreuses études ont déjà démontré que les caractéristiques chimiques d'un cours d'eau peuvent changer avec les saisons. Cette étude a pour but de revoir les relations débit- concentration sur un petit cours d'eau, dans le contexte des variations entre deux périodes climatiques. Pour ce faire, une analyse de régression entre le débit et six paramètres de qualité de d'eau (sodium, magnésium, conductivité, pH, azote total et le carbone organique dissous) provenant d'un petit bassin versant forestier (ruisseau Catamaran, N.-B., Canada) a été réalisée afin de déterminer la différence entre la saison sans glace et la saison avec glace. Des échantillons mensuels d'eau ont été récoltés sur le ruisseau Catamaran depuis 1990. Les analyses chimiques faites sur ses échantillons ont permis de déterminer les concentrations des paramètre étudiés. La plupart des variables de qualité ont démontré une relation significative avec le débit, sauf l'azote total. Les coefficients de détermination variaient entre 0.752 et 0.898, exception faite du carbone organique dissous dont le r2 était de 0.294. La conductivité était le paramètre dont le débit expliquait le plus la variance. Une étude des rapports des sommes des carrés des résidus a permis de déterminer que seul le pH requiert un modèle différent pour la période sans glace et la saison avec glace. Les variations saisonnières de la relation débit-pH revêt une importance significative pour les ruisseaux comme celui de Catamaran, qui incluent de nombreux habitats pour le saumon de l'Atlantique. Les résultats des analyses de régressions indiquent que lorsque la géochimie est plus complexe, comme c'est le cas pour le pH, il faut diviser les séries temporelles en sous-composantes saisonnières avant de tenter d'établir une relation débit-concentration.

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43

Elvers, Benedict Josua, Paul Schulan, Sebastian Pätsch, Christian Fischer e Carola Schulzke. "Combining a Low Valent Molybdenum(0) Center with a Strongly σ-Donating Mesoionic Carbene Chelate Ligand—Synthesis and Structural Characterization". Inorganics 10, n. 11 (20 novembre 2022): 216. http://dx.doi.org/10.3390/inorganics10110216.

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Triazolylidene ligands belong to a class of N-heterocyclic carbenes of growing chemical interest. Their precursors are readily available using Click chemistry and, therefore, highly modular for tuning their electronic characteristics. Due to their notable donor properties, these ligands are particularly suitable for modulating the electronic properties of the central ions of their complexes. Here, a bidentate bistriazolylidene which is a particularly strong donor ligand is combined with a low valent molybdenum(0) center and four carbon monoxide molecules as co-ligands. The novel complex exhibits characteristic electrochemical and IR-spectroscopic behavior. An X-ray structural analysis provides metrical details which are not entirely in agreement with spectroscopic data, likely going back to crystal packing effects. In comparison with precursor and ligand SCXRD data, notable geometrical changes induced by the coordination of the ligand to the metal can be observed. The analyses strongly support the bistriazolylidene ligand as being a particularly good donor of electron density towards the central metal. Potentially, these findings may support, in the future, the design of potent catalysts for the reductive activation of small molecules.

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44

Mancheño, María José, Pedro Ramírez-López, Mar Gómez-Gallego e Miguel A. Sierra. "Addition of Et3B to α,β-Unsaturated Alkoxychromium(0) Carbene Complexes". Organometallics 21, n. 5 (marzo 2002): 989–92. http://dx.doi.org/10.1021/om010926v.

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45

van der Westhuizen, Belinda, Pieter J. Swarts, Ian Strydom, David C. Liles, Israel Fernández, Jannie C. Swarts e Daniela I. Bezuidenhout. "Electrochemical illumination of thienyl and ferrocenyl chromium(0) Fischer carbene complexes". Dalton Transactions 42, n. 15 (2013): 5367. http://dx.doi.org/10.1039/c3dt32913e.

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46

Kuhl, Sébastien, Yves Fort e Raphaël Schneider. "Nickel(0)/N-heterocyclic carbene complexes catalysed arylation of aromatic diamines". Journal of Organometallic Chemistry 690, n. 24-25 (dicembre 2005): 6169–77. http://dx.doi.org/10.1016/j.jorganchem.2005.08.035.

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47

Alcaide, Benito, Luis Casarrubios, Gema Dominguez, Miguel A. Sierra e Angeles Monge. "Chromium(0) Carbene Complexes Bearing Imino Tethers: Synthesis and Photochemical Reactivity". Journal of the American Chemical Society 117, n. 20 (maggio 1995): 5604–5. http://dx.doi.org/10.1021/ja00125a030.

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48

Tlenkopatchev, Mikhail, e Serguei Fomine. "Molecular modeling of the olefin metathesis by tungsten(0) carbene complexes". Journal of Organometallic Chemistry 630, n. 2 (luglio 2001): 157–68. http://dx.doi.org/10.1016/s0022-328x(01)00932-9.

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49

Bezuidenhout, Daniela I., Belinda van der Westhuizen, Ian Strydom, Pieter J. Swarts, Jannie C. Swarts e Israel Fernández. "Synthesis and electrochemical investigation of chromium(0) ferrocenyl-substituted carbene complexes". Inorganica Chimica Acta 423 (novembre 2014): 184–92. http://dx.doi.org/10.1016/j.ica.2014.07.068.

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50

Danopoulos, Andreas A., e David Pugh. "A method for the synthesis of nickel(0) bis(carbene) complexes". Dalton Trans., n. 1 (2008): 30–31. http://dx.doi.org/10.1039/b714988c.

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