Bis- t-Butylimido complexes of tungsten(VI)

Abstract

WCl 6 reacts with Me 3SiNHCMe 3 or Me 3CNH 2 to give [W(NCMe 3)(μ-NCMe 3) Cl 2(NH 2CMe 3)] 2 which contains trans orientated chloro ligands. The reaction does not occur with Me 3SiNHR or RNH 2 (R = Me 2CH-, MeCH 2-). An interligand proton transfer between cis-orientated t-butylamido NH groups gives rise to the imido and amine ligands. [W(NCMe 3)(μ-NCMe 3)Cl 2(NH 2CMe 3)] 2 reacts with 4-picoline to give [W(NCMe 3)(μ-NCMe 3)Cl 2(4-pic)] 2 and [W(NCMe 3) 2Cl 2(4-pic) 2] while the bidentate ligands bipy and tmed give [W(NCMe 3) 2Cl 2(bipy)] and [W(NCMe 3) 2Cl 2(tmed)]. All the complexes retain the trans-chloro orientation. With strong sigma donors, L (L = PMe 3, PMePh 2, Me 3CNC), [W(NCMe 3)(μ-NCMe 3)Cl 2(NH 2CMe 3)] 2 reacts to give the complexes [W(NCMe 3)(μ-NCMe 3)Cl 2(L)] 2 which contain cis-chloro ligands. With t-butylamine [W(NCMe 3) 2 (NHCMe 3) 2] is formed but less sterically demanding amines (Me 2CHNH 2, MeCH 2NH 2) do not react similarly. Reaction of [W(NCMe 3)(μ-NCMe 3)Cl 2(NH 2CMe 3)] 2 with EtOH and Me 3CNH 2 forms [W(NCMe 3) 2(OEt) 2] x . WOCl 4 reacts with Me 3SiNHCMe 3 or Me 3CNH 2 to give a complex proposed as [WO(NCMe 3)Cl 2(NH 2CMe 3)] x which reacts further with bipy to form [W(NCMe 3) 2Cl 2(bipy)] and various uncharacterized oxo complexes by an oxo-imido exchange. The complexes were characterized by analytical data, IR, 1H and 13C NMR spectroscopy. The position of the t-butyl group quaternary carbon in the 13C NMR spectra differentiates between imido, amido and amine ligands.