PREPARATION AND CHARACTERIZATION OF MU-ALKYNE-HEXACARBONYLDICOBALT COMPLEXES DERIVED FROM 1,1'-DIALKYNYLFERROCENE - MOLECULAR-STRUCTURES OF ((ETA-5-C5H4C-EQUIVALENT-TO-CPH)2FE)(CO2(CO)6)2 AND ((ETA-5-C5H4C-EQUIVALENT-TO-CPH)2FE)CO2(CO)6

The reaction of 1,1'-dialkynylferrocene (eta5-C5H4C=CR)2Fe (1) R = Ph, SiMe3, Me, Fc; Fc = ferrocenyl) with excess octacarbonyldicobalt (2) results in the formation of dark green complexes {(eta5-C5H4C=CR)2 Fe)(Co2(CO)6}2 (3) (R = Ph, SiMe3, Me, Fc), in which a Co2(CO)6 group coordinates to each of the two C=C bonds of 1. When 1,1'-di(phenylethynyl)ferrocene (1a) was treated with an equimolar amount of 2, {(eta5-C5H4C=CPh)2Fe}Co2(CO)6 (4), as well as 3a, was obtained. In the thermal reaction of 4 intermolecular Co2(CO)6 group migration to give 3a was observed. Molecular structures of {(eta5-C5H4C=CPh)2Fe}{Co2(CO)6}2 (3a) and {(eta5-C5H4C=CPh)2Fe}Co2(CO)6 (4) have been determined by single-crystal X-ray analyses.