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, <b>1</b>; DMP = 2,6-dimethylphenyl = 2,6-(CH₃)₂–C₆H₃, <b>2</b>; Bn = benzyl = CH₂–C₆H₅, <b>3</b>; FPhen = 4-fluorophenyl = 4–F–C₆H₄, <b>4</b>; ClPhen = 4-chlorophenyl = 4–Cl–C₆H₄, <b>5</b>) as their MeCN or THF adducts <b>1</b>(MeCN)–<b>5</b>(MeCN) and <b>1</b>(THF)–<b>5</b>(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}] (<b>6</b>(MeCN)). The solvent ligand can be easily replaced, as exemplified for the reaction of <b>1</b>(MeCN), <b>4</b>(MeCN), and <b>5</b>(MeCN) with pyridine (py) or <b>1</b>(MeCN) with benzophenone (PhCOPh) to yield <b>1</b>(py), <b>4</b>(py), <b>5</b>(py) and <b>1</b>(PhCOPh). Furthermore, <b>1</b>(MeCN) and <b>2</b>(MeCN) react with [NMe₄]F and NEt₃·3HF to yield the tungstate(VI) imido pentafluorido salts [cat][W(NR)F₅] (R = Tol, <b>a</b>; DMP; <b>b</b>; cat = NMe₄, <b>7</b>; NEt₃H, <b>8</b>) <b>7a</b>–<b>8b</b>.