Reactions of (SiMe2)(GeMe2) doubly bridged biscyclopentadiene with iron carbonyl and tungsten carbonyl

Thermal treatment of (SiMe2)(GeMe2)(C5H4)2 (1) with Fe(CO)5 in refluxing xylene provided the normal doubly bridged biscyclopentadienyl diiron tetracarbonyl complex (SiMe2)(GeMe2)[(η5-C5H3)Fe(CO)]2(μ-CO)2 (2) and the degermylated product (SiMe2)[(η5-C5H4)Fe(CO)]2(μ-CO)2 (4), together with a novel complex (SiMe2)(η5-C5H3)(η5:η1-C5H3)[(GeMe2)Fe(CO)2][Fe(CO)2)] (3) containing an Fe–Ge bond, whose formation was accompanied by migration of bridging GeMe2 group from the ligand to iron atom. Similar treatment of 1 with W(CO)6 afforded the tungsten analogue of compound 4, (SiMe2)(η5-C5H3)(η5:η1-C5H3)[(GeMe2)W(CO)3][W(CO)3)] (6) and the degermylated product (SiMe2)[(η5-C5H4)W(CO)3]2 (7). A plausible mechanism for formation of 3, and 6 was proposed. The crystal structures of 3, and 6 were determined by X-ray crystallography.