SYNTHESIS AND PHOTOCHEMISTRY OF GERMYLSILYL, GERMYLSTANNYL, AND STANNYLGERMYL DERIVATIVES OF THE [(ETA(5)-C5H5)FE(CO)(2)] (FP) SYSTEM - FPSIME(2)GEME(2)FP, FPGEME(2)SNME(3), AND FPSNME(2)GEME(3)

New silicon, germanium, and tin complexes of the [(eta(5)-C5H5)Fe(CO)( 2)] (Fp) system containing silylgermyl and germylstannyl groups are re ported, FpSiMe(2)GeMe(2)Fp (4), FpGeMe(2)SnMe(3) (5), and its isomer F pSnMe(2)GeMe(3) (6). The bimetallic complex 4 undergoes photochemical transformation to three equilibrating isomers of an intermediate germy lene bridged complex [(eta(5)-C5H5)Fe(CO)](2)(mu-CO)(mu-GeMeSiMe(3)) ( 7a). No evidence was obtained for the formation of the isomeric silyle ne bridged intermediate [(eta(5)-C5H5)Fe(CO)](2)(mu-CO)(mu-SiMeGeMe(3) ) (7b), confirming the enhanced stability of germylene versus silylene intermediates. Complex 7a transforms slowly to a mixture of the cis a nd trans isomers of the doubly bridged germylene silylene complex [(et a(5)-C5H5)Fe(CO)](2)(mu-SiMe(2))(mu-GeMe(2)) (8). The germylstannyl co mplex 5 photoisomerizes to 6 prior to photoelimination of Me(2)Ge and Me(2)Sn to form FpSnMe(3) (40%) and FpGeMe(3) (60%), respectively. The same photoproduct distribution was obtained from the photochemical tr eatment of 6, but no isomerization to 5 was observed.