7-COORDINATE COMPLEXES OF MOLYBDENUM(II) AND TUNGSTEN(II) CONTAINING PYRIDINE-2-THIONATE AND PYRIMIDINE-2-THIONATE - CRYSTAL-STRUCTURE OF [W(CO)(3)(ETA(2)-PYMS)(2)] (PYMS=PYRIMIDINE-2-THIONATE)

Reaction of [Wl(2)(CO)(3)(NCMe)(2)] with two equivalents of K[pymS] (pymS = pyrimidine-2-thionate) has given the crystallographically characterised complex [W(CO)(3)(eta(2)-pymS)(2)] (1). The structure can be described as a distorted monocapped trigonal prism with a carbonyl ligand in the unique capping position. Equimolar quantities of Ml(2)(CO)(3)(NCMe)(2)] and L {for M = Mo or W, L = PPh(3); for M = W only, L = PPh(2) Cy or PPh(2) Nap (Nap = napthyl)} react to give [Ml(2)(CO)(3)(NCMe)L], followed by reaction in situ with K[pyS or pymS] (pyS = pyridine-2-thionate) afforded the complexes [Ml(CO)(3)L(eta(2)-pyS or pymS)] (2-7). The tungsten complexes [Wl(2)(CO)(3)LL'] {L = L' = PPh(3), PPh(2) Cy, PPh(2) Nap or L = PPhBz(2), L' = AsPh(3); L = PPh(3), L' = PPh(2)Bz, PPhBz(2) AsPh(2) or SbPh(3)) (prepared in situ) react with an equimolar amount of K[pymS] to give the S-monodentately coordinated pyrimidine-2-thionate complexes [Wl(CO)(3)LL'(eta(1)- S-pymS)] (8-15). Similarly, treatment of [Wl(2)(CO)(3){Ph(2)P(CH2)(n)PPh(2)]} (n = 1-6) (prepared in situ) with one equivalent of K[pyS] or K[pymS] yielded the monodentately attached pyrimidine-2-thionate or pyridine-2-thionate complexes [Wl(CO)(3){Ph(2)P(CH2)(n)PPh(2)}(eta(1)-S-pyS or -S-pymS)] (16-27). The molybdenum complex [MoI2(CO)(3){Ph(2)P(CH2)(2)PPh(2))} (prepared in situ) reacts with an equimolar amount of K[pymS] to give the bidentately coordinated pyrimidine-2-thionate dicarbonyl complex [Mol(CO)(2)(Ph(2)P(CH2)(2)PPh(2)}(eta(2)-pymS)] (28).