Formation and reactions of mono- and di-substituted derivatives of [µ4-Ge{CO2(CO)7}2], containing functional µ-GeRH or µ-GeRCl groups

Abstract

The reaction of µ₄-Ge{Co₂(CO)₇}₂]1 with GeRH₃(R = Et or Ph) has been found to give [µ₄-Ge{Co₂(CO)₇}{Co₂(CO)₆)(µ-GeRH)}]2 or [µ₄-Ge{Co₂(CO)₆(µ-GeRH)}₂]3 depending on the stoichiometries and conditions. Analogues of 2 or 3 with µ-GeMeCl groups form from 1 and GeMe(Cl)H₂. Reaction of 2 with [Co₂(CO)₈] gives an open cluster with a µ-Ge(R)Co(CO)₄ group which readily condenses to a closo-cluster with a Ge₂Co₄ core. Analogous reactions of 3 with [Co₂(CO)₆] ultimately give clusters [Co₄(µ₄-GeR)₂{µ-GeCo₂(CO)₇}(CO)₁₀] again via more-open intermediates. Corresponding species are obtained from the µ-GeMeCl compounds and [Co(CO)₄]^–. An X-ray structure analysis of [Co₄(µ₄-GeEt)₂{µ-GeCo₂(CO)₇}(CO)₁₀] has been performed: triclinic, space group P, a= 10.617(1), b= 16.895(3), c= 9.822(4)Å, α= 104.22(2), β= 94.40(2), γ= 102.03(1)°, Z= 2, R= 0.027, for 3516 data with l > 2σ(l). It reveals a structure consisting of a pseudo-octahedral Ge₂Co₄ unit, with one of the Co-Co bonds edge-bridged by a µ-GeCo₂(CO)₇ moiety.