N-Heterocyclic Carbene Ligands in Nonsymmetric Diiron Models of Hydrogenase Active Sites
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- 作者：Didier Morvan ; Jean-Franç ; ois Capon ; Fré ; dé ; ric Gloaguen ; Alan Le Goff ; Mathieu Marchivie ; Franç ; ois Michaud ; Philippe Schollhammer ; Jean Talarmin ; Jean-Jacques Yaouanc ; Roger
- 刊名：Organometallics
- 出版年：2007
- 出版时间：April 9, 2007
- 年：2007
- 卷：26
- 期：8
- 页码：2042 - 2052
- 全文大小：285K
- 年卷期：v.26,no.8(April 9, 2007)
- ISSN：1520-6041
文摘
Reaction of [Fe2{
-S(CH2)3S}(CO)6] (1) at room temperature with the N-heterocyclic carbenes IMe-(CH2)2-L (IMe = 1-methylimidazol-2-ylidene, L = NMe2, SMe) afforded the pentacarbonyl carbenederivatives [Fe2{-S(CH2)3S}(CO)5{IMe-(CH2)2-NMe2}] (2a) and [Fe2{-S(CH2)3S}(CO)5{IMe-(CH2)2-SMe}] (2b). Reaction of 1 with IMe-CH2-IMe at room temperature provided the dimer [{Fe2(-S(CH2)3S)(CO)5}2{-(IMe-CH2-IMe)}] (3) together with the chelated bis-NHC complex [Fe2{-S(CH2)3S}(CO)4{IMe-CH2-IMe}] (4a) as the major product. The analogous reaction of 1 with IMe-(CH2)2-IMe yielded the chelatedbis-NHC complex [Fe2(-S(CH2)3S)(CO)4{IMe-(CH2)2-IMe}] (4b). Addition of HBF4 to compound 4aafforded the stable bridging hydride complexes [Fe2(-H){-S(CH2)3S}(CO)4{IMe-CH2-IMe}](BF4) (5a,b)with NHC ligands in a basal/basal and basal/apical mode of coordination in 5a,b, respectively. Themolecular structures of 2a, 3, 4a,b, and 5a were confirmed by X-ray diffraction studies. Low-temperatureNMR studies on the protonation of 4a showed spectroscopic evidence for the formation of a very unstableterminal hydride and a bridging hydride species with a NHC ligand having a non classical mode ofcoordination via a C-4(5) bond. Cyclic voltammetry revealed that 4a is a catalyst for proton reduction.
-S(CH2)3S}(CO)6] (1) at room temperature with the N-heterocyclic carbenes IMe-(CH2)2-L (IMe = 1-methylimidazol-2-ylidene, L = NMe2, SMe) afforded the pentacarbonyl carbenederivatives [Fe2{-S(CH2)3S}(CO)5{IMe-(CH2)2-NMe2}] (2a) and [Fe2{-S(CH2)3S}(CO)5{IMe-(CH2)2-SMe}] (2b). Reaction of 1 with IMe-CH2-IMe at room temperature provided the dimer [{Fe2(-S(CH2)3S)(CO)5}2{-(IMe-CH2-IMe)}] (3) together with the chelated bis-NHC complex [Fe2{-S(CH2)3S}(CO)4{IMe-CH2-IMe}] (4a) as the major product. The analogous reaction of 1 with IMe-(CH2)2-IMe yielded the chelatedbis-NHC complex [Fe2(-S(CH2)3S)(CO)4{IMe-(CH2)2-IMe}] (4b). Addition of HBF4 to compound 4aafforded the stable bridging hydride complexes [Fe2(-H){-S(CH2)3S}(CO)4{IMe-CH2-IMe}](BF4) (5a,b)with NHC ligands in a basal/basal and basal/apical mode of coordination in 5a,b, respectively. Themolecular structures of 2a, 3, 4a,b, and 5a were confirmed by X-ray diffraction studies. Low-temperatureNMR studies on the protonation of 4a showed spectroscopic evidence for the formation of a very unstableterminal hydride and a bridging hydride species with a NHC ligand having a non classical mode ofcoordination via a C-4(5) bond. Cyclic voltammetry revealed that 4a is a catalyst for proton reduction.