Synthesis, fluxional behavior and structures of diethyldithiophosphate molybdenum complexes:: crystal structures of [Et4N][Mo(CO)4{η2-S2P(OEt)2}] and [Mo(CH3CN)(η3-C3H5)(CO)2{η2-S2P(OEt)2}]

The air-sensitive dithiophosphate complexes [Et4N][M(CO)(4){eta(2)-S2P(OEt)(2)}] (1, M = Mo; 2, M =W) are accessible by the reaction of M(CO)(4)(pip)(2) (pip = piperidine) (M = Mo, W) with NH4S2P(OEt)(2) in refluxing acetonitrile in the presence of Et4NBr. Complex 1 reacts with allyl bromide in CH3CN to give the complex [Mo(CH3CN)(eta(3)-C3H5)(CO)(2){eta(2)-S2P(OEt)(2)}] (3). The single-crystal structures of complexes 1 and 3 have been determined by X-ray diffraction analyses. Crystal data for 1: space group, C2/c with a = 13.088(7), b = 16.271(4), c = 11.366(7) Angstrom, beta = 93.88(5)degrees, V = 2414.9(21) Angstrom(3), Z = 4. The structure was refined to R = 0.031 and Rw = 0.031; Crystal data for 3: space group, Pna2(1) with a = 15.979(3), b = 8.613(2), c = 12.720(3) Angstrom, V = 1750.6(6) Angstrom(3), Z = 4. The structure was refined to R = 0.026 and Rw = 0.028. Treatment of 3 with piperidine results in the formation of the complex [Mo(eta(3)-C3H5)(CO)(2){eta(2)-S2P(OEt)(2)}(C5H10NH)] (4), in which the labile CH3CN ligand was substituted by C5H10NH. The rotational behaviors of complex 3 and 4 in solution state were detected by variable-temperature H-1-NMR spectroscopy. The mechanism can be described as a trigonal twist, which involves the rotation of the triangular face formed by the nitrogen ligand and the two sulfur atoms relative to the face formed by the allyl and the two carbonyl groups. The 16-electron dithiocarbamate complex [Mo(eta(3)-C3H5)(CO)(2)(eta(2)-S2CNC5H10)] (5) is produced by S2P(OEt)(2)(-) ligand replacement of 4 with C5H10NC(S)SH or the insertion reaction of CS2 into the Mo-N bond of 4 with releasing of the (EtO)(2)P(S)SH ligand. (C) 1999 Elsevier Science S.A. All rights reserved.