The reactions of a series of silyl- and germyl-molybdenum hydrido complexes, [MoH3E(Ar)[Ph2PCH2CH2P(Ph)C6H4–o]2}]
(E = Si, Ge; Ar = Ph, C6F5, 4-Me2NC6H4), with various isocyanides result in the liberation of hydrogen and formation of the molybdenum isocyanide complexes, [MoH(CNR)E(Ar)[Ph2PCH2CH2P(Ph)C6H4–o]2}]
(R =
t-Bu, cyclo-C6H11, PhCH2, Ph, 2,6-Me2C6H3), in which the isocyanide ligand ligates at the site opposite to the E atom. The new complexes show in their solid-state IR spectra an intense band assignable to CN stretching, which is found to be considerably lower than that of the corresponding free isocyanide (more than 100 cm−1), demonstrating the existence of π-back-bonding from the electron-rich metal centre to the isocyanide ligand. Both X-ray crystallographic analyses and spectroscopic evidence confirm the strong trans-influence of the Si group.
一系列
硅锆钼氢配合物[MoH3E(Ar)[Ph2PCH2CH2P(Ph)
C6H4–o]2}](E = Si,Ge;Ar = Ph,
C6F5,4-Me2N )与各种异
氰化物的反应导致氢的释放和
钼异
氰配合物的形成,[MoH(CNR)E(Ar)[Ph2PCH2CH2P(Ph) –o]2}](R = t-Bu,cyclo-
C6H11,PhCH2,Ph,2,6-Me2C6H3),其中异
氰化物
配体在E原子的对面配位。这些新配合物在其固态红外光谱中显示出可归属于CN伸缩的强烈谱带,发现其明显低于相应的自由异
氰化物(超过100 cm−1),表明富电子
金属中心向异
氰化物
配体存在π反向键合。X射线晶体学分析和光谱证据均证实Si基团具有较强的反位影响。