W(CO)3(PMTA) (PMTA = MEN(CH2CH2NME2)2) AS A STARTING MATERIAL FOR SYNTHESES OF W(CO)3(PR3)3, W(CO)3(ETA-6-ARENE), AND THE PROTONATED W(H)(CO)3(PR3)3+ COMPLEXES

A new and improved method for the synthesis of M(CO)3(PMTA) (M = W, Mo) from M(CO)6 and PMTA (MeN(CH2CH2NMe2)2) is described. The tridentate nitrogen ligand in W(CO)3(PMTA) is replaced, under relatively mild conditions, by tertiary phosphines (PMe3, PEt3, PMe2Ph, PMePh2, PhP(CH2CH2PPh2)2, CH3C(CH2PPh2)3, and Ph2P(CH2)(n)PPh2 where n = 1, 2) and arenes (C6H6, MeC6H5, p-Me2C6H4, C6Me6, C6H5Cl), which provides a general synthetic method for the preparation of W(CO)3(PR3)3 and W(CO)3(eta-6-arene) complexes. The reactions of W(CO)3(L)3 [L = PMe3, PEt3, PMe2Ph, PMePh2, PhP(CH2CH2PPh2)2, and CH3C(CH2PPh2)3] with CF3SO3H in CH2Cl2 solution yield the hydrido derivatives W(H)(CO)3(L)3+ which were characterized by their H-1 and P-31 NMR spectra at different temperatures. These studies show the W(H)(CO)3(L)3+ complexes to be fluxional as a result of both hydride and phosphine ligand migration.