REACTION OF FE(CO)(2)(ETA(2)-CS2)(P(OR)(3))(2) WITH PHOSPHINES - DESULFURIZATION 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 equival ents of PBu3 in a minimum volume of a polar solvent such as acetonitri le or dimethylsulfoxide afforded the thiocarbonyl derivative Fe(CO)(2) (CS){P(OPh)(3)}(2) 2 in ca. 80% yield whereas reaction in solvents suc h 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 P Bu3 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 o f 2 and Fe(CO),(P(OPh),), were determined and are very similar. Both c ompounds are trigonal bipyramidal about the Fe atom with trans apical phosphite ligands and a trigonal planar arrangement of CO/CS groups. T he CS ligand in 2 was found to be disordered over two sites with occup ancies 0.63 and 0.37. (C) 1998 Elsevier Science S.A. All rights reserv ed.