Dioxomolybdenum(VI) and dioxotungsten(VI) complexes supported by an amido ligand

Abstract

Stepwise addition of one equivalent of n-butyllithium and trimethylsilyl chloride to 2-tert-butylmercaptoaniline affords the new ligand 1-(Me(3)SiNH)-2-(t- BuS)C(6)H(4)(LH), that reacts with one equivalent of butyllithium to its lithium salt LLi. Dioxodichloromolybdenum [MoO(2)Cl(2)] and dioxodichlorotungsten dimethoxyethane [WO(2)Cl(2)(dme)] react in tetrahydrofuran solution at low temperature with two equivalents LLi to monomeric dioxomolybdenum(VI) [MoO(2)L(2)] (1) and dioxotungsten(VI) complex [WO(2)L(2)] (2) employing two bidentate amido thioether ligands. The crystallographic determination of the molecular structures of 1 and 2 show evidence for M center dot center dot center dot S contacts. The reaction of [ MoO2Cl2] with LLi in tetrahydrofuran solution at room temperature leads next to 1 to two compounds where silyl group migration from nitrogen to oxygen atoms occurs forming [Mo(= NL')(2)(OSiMe)(2)] (3) and [Mo(= NL')(2)(OSiMe(3))L] (4, L' = N-2-t-BuSC(6)H(4)) as determined by NMR spectroscopy. Compound 4 was isolated in low yield and its molecular structure determined by X-ray crystallography. Higher yields of a bisimido complex can be obtained by the direct reaction of one equivalent of LLi with [Mo(NAr)(2)Cl(2)(dme)] (Ar = 2,6-Me(2)C(6)H(4)) forming [Mo(NAr)(2)LCl] (5).