Reaction of Fe(CO)2(η2-CS2){P(OR)3}2 with phosphines:: desulphurization versus substitution.: Crystal structures of Fe(CO)2(CS){P(OPh)3}2 and Fe(CO)3{P(OPh)3}2

The reaction of Fe(CO)(2)(eta(2)-CS2){P(OPh)(3)}(2) 1 with two equivalents of PBu3 in a minimum volume of a polar solvent such as acetonitrile or dimethylsulfoxide afforded the thiocarbonyl derivative Fe(CO)(2)(CS){P(OPh)(3)}(2) 2 in ca. 80% yield whereas reaction in solvents such as dichloromethane or benzene afforded the substitution products Fe(CO)(2)(eta(2)-CS2){P(OPh)(3)}(PBu3) and Fe(CO)(2)(eta(2)-CS2)(PBu3)(2). Although desulphurization of Fe(CO)(2)(eta(2)-CS2){P(OR)(3)}(2) by PBu3 in polar solvents is not a general route to Fe(CO)(2)(CS){P(OR)(3)}(2) for all R, the new compound Fe(CO)(2)(CS){P(OEt)(3)}(2) has been obtained and characterised spectroscopically. The crystal structures of 2 and Fe(CO),(P(OPh),), were determined and are very similar. Both compounds are trigonal bipyramidal about the Fe atom with trans apical phosphite ligands and a trigonal planar arrangement of CO/CS groups. The CS ligand in 2 was found to be disordered over two sites with occupancies 0.63 and 0.37. (C) 1998 Elsevier Science S.A. All rights reserved.