Synthesis and structure of a series of new d1-aryl imido-vanadium(IV) complexes stabilized by N-donor ligands

A family of new coordination vanadium(IV) compounds supported by a terminal or bridged aryl imido ligand are reported. Reaction of V(NMe2)(4) with anilines ArNH2, where Ar = 2,6-i-Pr-2-C6H3, 2,6-Met-C6H3, Ph, 2,6-Cl-2-C6H3, and C6F5, afforded the diamagnetic imido-bridged complexes [V(NAr)(NMe2)(2)](2) (1a-e). Chlorination of 1a-e with trimethylchlorosilane afforded complexes 2a-e formulated as [V(=NAr)Cl-2(NHMe2)(x)](n). One-pot reaction of V(NMe2)4 with ArNH2 in the presence of an excess of trimethylchlorosilane gave the five-coordinate compound [V(=NAr)Cl-2(NHMe2)(2)] (3a-e). Reaction of 3a-e with pyridine, bipyridine (bipy), or N,N,N',N'-tetramethylethylenediamine (tmeda) gave respectively the six-coordinate tris- or bis(pyridine) adducts [V(=NAr)Cl-2(Py)(3)] (4a-e) or [V(=NAr)Cl-2(Py)(2)(NHMe2)] (5a), bipyridine complexes [V(=NAr)Cl-2(bipy)(NHMe2)] (5a-e) and [V(=NAr)Cl-2(bipy)(Py)] (9a), and tmeda adduct [V(=NAr)Cl-2(tmeda)(NHMe2)] (10a). Moreover, five-coordinate complexes free of NHMe2 ligands, such as [V(=NAr)Cl-2(Py)(2)] (5a), [V(=NAr)Cl-2(bipy)] (8a), and [V(=NAr)Cl-2(tmeda)] (11a), were directly prepared starting from precursors 2a-e. All compounds were totally characterized by spectroscopic methods (IR,H-1 NMR for diamagnetic complexes, and EPR for paramagnetic complexes), elemental analysis, magnetism, and single-crystal X-ray diffraction studies for 1b, 3a, 3d, 4b, 4d, 7c, 10a, and 11a.