New seven-coordinate thiourea and N,N,N′,N′-tetramethylthiourea complexes of molybdenum(II) and tungsten(II)

Abstract

Abstract The compounds [MI2(CO)3(NCMe)2] (M = Mo or W) react with one equivalent of thiourea (tu) in MeOH or N,N,N′,N′-tetramethylthiourea (tmtu) in CH2Cl2 at room temperature to initially afford the monoacetonitrile compounds [MI2(CO)3(NCMe)L] (L = tu or tmtu) which rapidly transform to the isolated iodide bridged dimers, [M(μ-I)I(CO)3L]2 with loss of acetonitrile. Reaction of [WI2(CO)3(NCMe)2] with two equivalents of tu or tmtu gave the expected mononuclear seven-coordinate compounds [WI2(CO)3L2]. However, reaction of [MoI2(CO)3(NCMe)2] with two equivalents of tu or tmtu rapidly affords the iodide-bridged dimers [Mo(μ-I)I(CO)2L2]2 with loss of carbon monoxide from [MoI2(CO)3L2]. The low temperature (−70°C) 13C NMR spectrum of [Mo(μ-I)I(CO)2 {SC(NMe2)2}2]2 suggests the complex is based on two capped octahedra with a carbonyl ligand capping each octahedral face.