Syntheses and structures of vinyl and aryl derivatives of carbonyl halide iron complexes

cis,trans-Fe(CO)2(PMe3)2(p-Y-C6H4)X [X=Br, Y=H (4a), MeO (4b), Cl (4c), F (4d), Me (4e); X=I, Y=H (5); X=Cl, Y=H (6)] and cis,trans-Fe(CO)2(PMe3)2(σ-CHCH2)X [X=Br (7); X=I (8); X=Cl (9)] are prepared by reacting dihalide complexes cis,trans,cis- Fe(CO)2(PMe3)2X2 [X=Br (1), X=I (2), X=Cl (3)] with Grignard reagents p-Y-C6H4-MgBr (Y=H, OMe, Cl, F, Me) or CH2CH–MgBr and with lithium reagents PhLi, CH2CH–Li. With both reagents, the reaction proceeds following two parallel pathways: one is the metallation reaction which yields alkyl derivatives, the other affords 17 electron complexes [Fe(CO)2(PMe3)2X] via monoelectron reductive elimination. The influence of the halides and organometallic reagents on the yield of the metallation reaction is discussed. The solution structure of the complexes is assigned on the basis of IR and 1H, 13C, 19F, 31P NMR spectra. The solid state structure of complexes 4a, 5 and 6 is determined by single crystal X-ray diffractometric methods.