UV irradiation of [M(CO)3(η-arene)] and Me3SiCCSiMe3 gives [M(CO)2CC(SiMe3)2}(η-arene)] (M = Cr, arene = C6H2Me4-1,2,3,5 2V, C6H3Me3-1,2,3 3V or C6H6 4V; M = Mo, arene = C6Me6 5V or C6H3Me3-1,3,5 6V). The crystal structure of [Cr(CO)2CC(SiMe3)2}(η-C6H6)] 4V confirms the presence of the vinylidene ligand; the complex has approximate Cs symmetry with the C(SiMe3)2 plane orthogonal to the arenecentroid–Cr–Cα–Cβ plane. Voltammetry and IR and NMR spectroscopy show that in solution [Mo(CO)2CC(SiMe3)2}(η-C6H3Me3-1,3,5)] 6V thermally equilibrates with the alkyne isomer [Mo(CO)2(η-Me3SiCCSiMe3)(η-C6H3Me3-1,3,5)] 6A. The vinylidene complexes [M(CO)2CC(SiMe3)2}(η-arene)] 2V–6V undergo one-electron oxidation to the alkyne cations [M(CO)2(η-Me3SiCCSiMe3)(η-arene)]+ 2A+–6A+via fast, redox-induced vinylidene-to-alkyne isomerisation. These cations are reduced to the neutral alkyne complexes [M(CO)2(η-Me3SiCCSiMe3)(η-arene)] 2A–6A which slowly isomerise thermally to the neutral vinylidene complexes 2V–6V. Paramagnetic vinylidene and alkyne complex cations have been characterised by ESR spectroscopy; unpaired electron density is extensively delocalised from the metal centre to the C2 ligand, in agreement with the results of EHMO calculations.
紫外线照射[M(CO)3(η-
烯烃)]和 Me3SiCCSiMe3 得到[M(CO)2CC(SiMe3)2}(η-
烯烃)](M = Cr,炔 = C6H2Me4-1,2,3,5 2V,C6H3Me3-1,2,3 3V 或
C6H6 4V;M =
MO,炔 = C6Me6 5V 或 C6H3Me3-1,3,5 6V)。[Cr(CO)2CC(SiMe3)2}(η- )] 4V 的晶体结构证实了亚
乙烯基配体的存在;该配合物具有近似 Cs 对称性,C(SiMe3)2 平面与亚乙基-Cr-Cα-Cβ 平面正交。伏安法、红外光谱和核磁共振光谱显示,在溶液中,[
MO(CO)2CC(SiMe3)2}(η-C6H3Me3-1,3,5)] 6V 与
炔烃异构体[
MO(CO)2(η-Me3SiCCSiMe3)(η-C6H3Me3-1,3,5)] 6A 发生热平衡。亚
乙烯基络合物 [M(CO)2CC(SiMe3)2}(η-arene)] 2V-6V 经过单电子
氧化反应生成炔阳离子 [M(CO)2(η-Me3SiCCSiMe3)(η-arene)]+ 2A+-6A+,并通过
氧化还原引起的亚
乙烯基与炔的快速异构化反应。这些阳离子被还原成中性
炔烃络合物[M(CO)2(η-Me3SiCCSiMe3)(η-
烯)]2A-6A,这些
炔烃络合物在热作用下缓慢异构化成中性亚
乙烯基络合物 2V-6V。顺磁性的亚
乙烯基和
炔烃配合物阳离子已通过 ESR 光谱法进行了表征;非配对电子密度从
金属中心广泛分散到 C2
配体上,这与 EH
MO 计算的结果一致。