Substitution reactions of [Ge2Co4Fe2(CO)21] with methylgermanes, and its decarbonylation. Structures of [Fe2{µ4-GeCo2(CO)6(µ-GeMe2)}2(CO)7] and [Fe3{µ3-GeCo(CO)4}2(CO)9]

Abstract

The compound GeMe₂H₂ reacted with [Fe₂{µ₄-Ge[Co₂(CO)₇]}₂(CO)₇], to replace only the µ-CO on the Co–Co bonds, forming [Fe₂{µ₄-Ge[Co₂(CO)₆(µ-GeMe₂)]}₂(CO)₇]. The monosubstituted product [Fe₂{µ₄-Ge[Co₂(CO)₇]}{µ₄-Ge[Co₂(CO)₆(µ-GeMe₂)]}(CO)₇] and similar products from GeMeH₃ are also indicated. A crystal structure analysis of [Fe₂{µ₄-Ge[Co₂(CO)₆(µ-GeMe₂)]}₂(CO)₇] confirmed an extended core of six GeM₂ triangles, linked through the germanium apices and the Co–Co or Fe–Fe edges. Heating [Fe₂{µ₄-Ge[Co₂(CO)₇]}₂(CO)₇] at 50–60 °C for 4–7 weeks yielded as major product [Fe₂Co₄Ge₂(CO)_n](n= 19 or 20) whose spectroscopic properties indicate a square-bipyramidal cluster with a Fe₂Co₂Ge₂ core. The minor product was the crystallographically characterised closo-trigonal-bipyramidal cluster [Fe₃{µ₃-GeCo(CO)₄}₂-(CO)₉] with a Ge₂Fe₃ core.