A CYCLOPROPENYLIDENE APPROACH TO TRICARBIDE COMPLEXES - SYNTHESIS ANDSTRUCTURE OF [M(CO)(5)(MU(2)-C-3(OCH2CH3))FE(CO)(2)(CP)] (M=CR, MO, W)

The diethoxycyclopropenylidene complexes [M(CO)(5){C-3(OCH2CH3)(2)}] ( M = Cr, Mo, W) react with K[Fe(CO)(2)(Cp)] to give the bimetallic cycl opropenylidene complexes [M(CO)(5){mu(2)-C-3(OCH2CH3)}Fe(CO)(2)(Cp)], but the second ethoxide is not displaced by excess K[Fe(CO)2(Cp)]. Spe ctroscopic evidence (H-1 NMR, C-13 NMR, and IR) as well as a X-ray cry stal structure determination of [Cr(CO)(5){mu(2)-C-3(OCH2CH3)}Fe(CO)(2 )-(Cp)] suggests that the central C-3 ring has a great deal of cyclopr openium character.