Isocyanate Route to Tungsten(VI) Imido Fluorido Complexes

A general synthetic route for tungsten(VI) organoimido fluorido complexes is reported, which relies on the key metathesis of organo isocyanates and tungsten(VI) oxo tetrafluoride or its acetonitrile adduct [WOF₄(MeCN)]. The reaction of 4-tolyl isocyanate, 2,5-dimethylphenyl isocyanate, benzyl isocyanate, 4-fluorophenyl isocyanate and 4-chlorophenyl isocyanate with [WOF₄] or [WOF₄(MeCN)] at 100 °C in acetonitrile (MeCN) or tetrahydrofuran (THF) afforded the imido complexes [W(NR)F₄(L)] (R = Tol = tolyl = 4-CH₃-C₆H₄, 1; DMP = 2,6-dimethylphenyl = 2,6-(CH₃)₂-C₆H₃, 2; Bn = benzyl = CH₂-C₆H₅, 3; FPhen = 4-fluorophenyl = 4-F-C₆H₄, 4; ClPhen = 4-chlorophenyl = 4-Cl-C₆H₄, 5) as their MeCN or THF adducts 1(MeCN)-5(MeCN) and 1(THF)-5(THF), respectively. Similarly, treatment of [WOF₄(MeCN)] with 1,4-phenylene diisocyanate in acetonitrile afforded the dinuclear complex [{WF₄(MeCN)}₂{μ-1,4-NC₆H₄N}] (6(MeCN)). The solvent ligand can be easily replaced, as exemplified for the reaction of 1(MeCN), 4(MeCN), and 5(MeCN) with pyridine (py) or 1(MeCN) with benzophenone (PhCOPh) to yield 1(py), 4(py), 5(py) and 1(PhCOPh). Furthermore, 1(MeCN) and 2(MeCN) react with [NMe₄]F and NEt₃·3HF to yield the tungstate(VI) imido pentafluorido salts [cat][W(NR)F₅] (R = Tol, a; DMP; b; cat = NMe₄, 7; NEt₃H, 8) 7a-8b.