A further study of the reaction of methylgermane with [Co2(CO)8], and some interconversions of the products. Crystal and molecular structures of [Co2{µ-Ge(Me)Co(CO)4}(CO)7] and [Co4(µ-4-GeMe)2{µ-Ge(Me)Co(CO)4}(CO)10], an edge-bridged square-bipyramidal Ge2Co4 species

Abstract

The compound [CoH(CO)₄] has been established as a stoichiometric product in the fast reaction of GeMeH₃with [Co₂(CO)₈] to form [Co₂{µ-Ge(Me)Co(CO)₄}(CO)₇]1. A prolonged reaction with an excess of GeMeH₃ yields [Co₂{µ-Ge(Me)Co(CO)₄}₂(CO)₆]2, accompanied by a hydride species [Co₂(GeMeH)(CO)_x](x= 7 or 8) when the excess is large. Heating this latter mixture yields [Co₄(µ₄-GeMe)₂{µGe(Me)Co(CO)₄}(CO)₁₀]3, shown by X-ray crystallography to contain the Co₄(µ₄-GeMe)₂ square-bipyramid core, edge-bridged by a µ-Ge(Me)[Co(CO)₄] unit. The bridged Co atoms carry two terminal CO groups, and the non-bridged ones, three. The crystal structures of compound 1[triclinic, space group P, Z= 2, a= 8.626(6), b= 8.656(5), c= 13.381(9)Å, α= 88.25(5), β= 84.72(5), γ= 66.26(4)°, R= 0.0649 for 1614 reflections with I > 3σ(I)] and 3[monoclinic, space group C2/m Z= 4, a= 12.330(6), b= 12.302(3), c= 18.815(9)Å, β= 92.93(3)°, R= 0.0344 for 1136 reflections with I 3σ(I)] have been determined and are compared with that of 2, and spectroscopic properties are discussed, including heavy-atom vibrations of 1