Facile conversion of (η5-C5R5)M(CO)2 - halide complexes to halomethyl, alkoxymethyl, and cyanomethyl derivatives (R = H, CH3; M = Fe, Ru; halide = Cl, Br, I)

Article abstract of DOI:10.1016/0022-328X(92)83185-K

The CpM(CO)2-X complexes (M = Fe, Ru; X = Cl, Br; Cp = η⁵-C5H5, Cp^* = η⁵-C5Me5) are completely converted to the corresponding halomethyl derivatives over a 20-30 min period when ethereal diazomethane is added dropwise in the presence of Cu powder.Product work-up involves only simple extraction of the crude product with hexane followed by recrystallization at -40 deg C.Formation of iodomethyl derivatives from iodide precursors requires considerably longer CH2N2 addition times and cannot be completely freed of the starting iodide complexes.Fortunately, iodomethyl complexes can be prepared in 80-95percent isolated yield by treating the chloromethyl or bromomethyl derivatives with NaI in acetone/Et2O.The CpFe(CO)2CH2I and Cp^*Fe(CO)2CH2I complexes are the most sensitive, decomposing rapidly to polymethylene and the parent iodide complexes upon standing at room temperature.Metathetical reactions of the halomethyl complexes to give alkoxymethyl and cyanomethyl derivatives are described.