A SERIES OF NOVEL BINUCLEAR IRON-RHODIUM COMPLEXES PREPARED FROM ETHYNYLFERROCENE

The chlororhodium(I) compound [RhCl(PiPr(3))(2)](2) (1) reacts with et hynylferrocene (2) by oxidative addition to give the alkynyl(hydrido)r hodium(III) complex [RhH(C=CFc)Cl(PiPr(3))(2)] (3) almost quantitative ly [Fc = (eta(5)-C5H4-)Fe(eta(5)-C5H5)]. Compound 3 is slowly converte d in benzene at ro om temperature to the vinylidene isomer trans-[RhCl (=C=CHFc)(PiPr(3))(2)] (4). Treatment of 4 with Grignard reagents RMgX affords the phenyl- and vinylrhodium(I) derivatives trans-[Rh(R)(=C=C HFc)(PiPr(3))(2)] (5, 6) of which the latter (R = CH=CH2) rearranges t o the isomeric eta(3)-2-4-butadienyl complex [Rh(eta(3)-trans-CH2CHC=C HFc)(PiPr(3))(2)] (8). The corresponding eta(3)-allyl compound [Rh(eta (3)-anti-CH2CH=CHFc)(PiPr(3))(2)] (7) is obtained from 4 and CH3MgI, p ossibly via trans-[Rh(CH3)(=C=CHFc)(PiPr(3))(2)] as an intermediate. T he X-ray crystal structure analysis of 7 confirms the anti position of the ferrocenyl group at the allylic ligand.