C–C and C–N Couplings in Reactions of the Benzylidyne-Bridged Complex [Mo2Cp2(μ-CPh)(μ-PCy2)(CO)2] with Small Unsaturated Organics

The ability of the title compound to promote C–C coupling processes has been analyzed by examining its reactions with diazoalkanes, alkynes, and other unsaturated organic molecules. The title compound reacted with N2CPh2 at room temperature to give a mixture of ketenyl complex [Mo2Cp2{μ-κ1:η2-C­(Ph)­CO}­(μ-PCy2)­(CO)­(κ1-N2CPh2)] and carbyne complex [Mo2Cp2(μ-CPh)­(μ-PCy2)­(CO)­(κ1-N2CPh2)], products which can be converted into each other by addition/removal of CO, respectively. In contrast, denitrogenation took place rapidly in analogous reactions with diazomethane and benzylazide at room temperature, to yield, respectively, the corresponding alkenyl [Mo2Cp2{μ-κ1:η2-C­(Ph)­CH2}­(μ-PCy2)­(CO)2] and iminoacyl [Mo2Cp2{μ-C­(Ph)­NCH2Ph}­(μ-PCy2)­(CO)2] derivatives, following from selective C–C and C–N couplings. The title compound reacted at 333 K with methyl propiolate to give the corresponding propenylylidene derivative [Mo2Cp2{μ-κ2:η3-CPhCHC­(CO2Me)}­(μ-PCy2)­(CO)2], as a result of selective coupling of the carbyne ligand to the terminal carbon of the alkyne. A related complex could be obtained when using the internal alkyne dimethyl acetylenedicarboxylate.

本研究通过考察标题化合物与重氮烷烃、炔烃及其他不饱和有机分子的反应，分析了其促进碳-碳（C–C）偶联过程的性能。
标题化合物于室温下与二苯基重氮甲烷（N₂CPh₂）反应，得到烯酮基配合物[Mo₂Cp₂{μ-κ1:η2-C(Ph)CO}(μ-PCy₂)(CO)(κ1-N₂CPh₂)]与卡拜配合物[Mo₂Cp₂(μ-CPh)(μ-PCy₂)(CO)(κ1-N₂CPh₂)]的混合物；其中Cp为环戊二烯基（cyclopentadienyl），PCy₂为桥联二环己基膦配体，CO为一氧化碳。该组产物可分别通过添加或移除CO实现相互转化。
与之相对，标题化合物与重氮甲烷、叠氮苄在室温下发生类似反应时会快速脱氮，分别生成相应的烯基衍生物[Mo₂Cp₂{μ-κ1:η2-C(Ph)CH₂}(μ-PCy₂)(CO)₂]与亚胺酰基衍生物[Mo₂Cp₂{μ-C(Ph)NCH₂Ph}(μ-PCy₂)(CO)₂]，该过程源于选择性碳-碳偶联与碳-氮偶联。
标题化合物于333 K下与丙炔酸甲酯反应，得到相应的丙烯亚基衍生物[Mo₂Cp₂{μ-κ2:η3-CPhCHC(CO₂Me)}(μ-PCy₂)(CO)₂]，该产物源于卡拜配体与炔烃末端碳原子的选择性偶联。
使用内炔烃乙炔二羧酸二甲酯时，可得到结构相关的配合物。