Organoimido complexes of tungsten. X-ray crystal structures of W(NC 6H 11)Cl 2(PMe 3) 3, [W(NC 6H 11)Cl 2(PMe 3) 3]O 3SCF 3, [W(NC 6H 11)Cl(PMe 3) 4]BPh 4, W[NSi( o-MeC 6H 4) 3]Cl 2(PMe 3) 3, W[NB(mes 2)] 2Cl 2(PMe 3) 2, {W(NPh)Cl[O 2C 2(CF 3) 4] 2}Li and WCl 4(PMe 2Ph) 3

Abstract

The cyclohexylimido complex of tungsten(VI), [W(NCy)Cl 4] 2 ( 1), is reduced by Na/Hg in the presence of PMe 3 to give cis,mer-W IV(NCy)Cl 2(PMe 3) 3 ( 2). Interaction of 2 with AgO 3SCF 3 in THF gives the tungsten(V) complex [W(NCy)Cl 2(PMe 3) 3]O 3SCF 3( 3); with NaBPh 4 in the presence of PMe 3 [W(NCy)Cl(PMe 3) 4]BPh 4 ( 4) is obtained. Interaction of WCl 2(PMe 3) 4 with the new organoazide ( o-tolyl) 3Si(N 3) produced W[NSi( o-tolyl) 3] Cl 2(PMe 3) 3 ( 5), while with (mesityl) 2B(N 3), cis,cis,trans-W[NB(mes) 2] 2Cl 2(PMe 3) 2 ( 6) is obtained. Interaction of [W(NPh)Cl 4] 2 with dilithium perfluoropinacolate gives Li{W (NPh)Cl[O 2C 2(CF 3) 4] 2} ( 7). The structures listed in the title have been determined by X-ray crystallographic study. In complexes 2–7 the metal has octahedral geometry. The WN(imido) distances vary from 1.69(1) Å in complex 4, a tungsten(IV) species, to 1.78(1) Å in the tungsten(VI) bis-imido complex 6, with no simple correlation with the oxidation state of the metal. The trans-lengthening effect of the imido function also varies, with the greatest effect generally in the tungsten(V) complex 3. No lengthening seems to occur in the tungsten(IV) complexes 2 and 4, but there is a slight effect in complex 5. The complex WCl 4(PMe 2Ph) 3 has a capped octahedral geometry.