Iron Complexes Containing the Tripodal Tetraphosphine Ligand P(CH(2)CH(2)PMe(2))(3)

The preparation and characterization of iron(II) complexes containing the tripodal tetraphosphine ligand tris[2-(dimethylphosphino)ethyl]phosphine, P(CH(2)CH(2)PMe(2))(3) (PP(3), 1), are reported. The complex FeCl(2)(PP(3)) (2) was formed by the reaction of PP(3) with anhydrous iron(II) chloride. The complexes FeHCl(PP(3)) (3) and FeH(2)(PP(3)) (4) were formed by the reaction of 2 with lithium aluminum hydride. Likewise, the complexes FeMeCl(PP(3)) (5) and FeMe(2)(PP(3)) (6) were formed by the reaction of 2 with methyllithium or dimethylmagnesium. Reaction of 2 with CO afforded a mixture of isomeric carbonyl chloride complexes [Fe(CO)Cl(PP(3))](+) (7 and 8). Reaction of 2 with PPh(3) afforded [Fe(PPh(3))Cl(PP(3))](+) (9). The air-sensitive complexes 2-9 were characterized by multinuclear NMR spectroscopy, and 9 was characterized by X-ray crystallography. Crystals of 9 (BPh(4) salt), C(54)H(65)BClFeP(5), M 971.09, are monoclinic, space group P2(1)/c, a = 13.246(3) Å, b = 30.314(2) Å, c = 14.338(2) Å, beta = 100.92(2) degrees, Z = 4; R = 0.058.