Seven-coordinate complexes of molybdenum(II) and tungsten(II) containing pyridine-2-thionate and pyrimidine-2-thionate. Crystal structure of [W(CO) 3( η2-pymS) 2] (pymS = pyrimidine-2-thionate)

Abstract

Reaction of [WI 2(CO) 3(NCMe) 2] with two equivalents of K[pymS] (pymS = pyrimidine-2-thionate) has given the crystallographically characterised complex [W(CO) 3( η 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 [MI 2(CO) 3(NCMe) 2] and L{for M = Mo or W, L = PPh 3; for M = W only, L = PPh 2Cy or PPh 2Nap (Nap = napthyl)} react to give [MI 2(CO) 3(NCMe)L], followed by reaction in situ with K[pyS or pymS] (pyS = pyrimidine-2-thionate) afforded the complexes [MI(CO) 3L( η 2-pyS or pymS)] ( 2–7). The tungsten complexes [WI 2(CO) 3LL′] {L = L′ = PPh 3, PPh 2Cy, PPh 2Nap or L = PPhBz 2, L′ = AsPh 3; L = PPh 3, L′ = PPh 2Bz, PPhBz 2, AsPh 3 or SbPh 3} (prepared in situ) react with an equimolar amount of K[pymS] to give the S-monodentately coordinated pyrimidine-2-thionate complexes [WI(CO) 3LL′( η 1-S-pymS)] ( 8–15). Similarly, treatment of [WI 2(CO) 3{Ph 2P(CH 2) 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 [WI(CO) 3{Ph 2P(CH 2) n PPh 2}( η 1-S-pyS or -S-pymS)]( 16–27). The molybdenum complex [MoI 2(CO) 3{Ph 2P(CH 2) 2PPh 2}] (prepared in situ) reacts with an equimolar amount of K[pymS] to give the bidentately coordinated pyrimidine-2-thionate dicarbonyl complex MoI(CO) 2{Ph 2P(CH 2) 2PPh 2}( η 2-pymS)] ( 28).