Synthesis, structures, and olefin polymerization capability of vanadium(4+) imido compounds with fac-N3 donor ligands

One-pot reactions of V(NMe2)(4) with a range of primary alkyl- and arylamines RNH2 and Me3SiCl afforded the corresponding five-coordinate vanadium(4+) imido compounds V(NR)Cl-2(NHMe2)(2)[R = 2,6-(C6H3Pr2)-Pr-i (1a, previously reported), 2-(C6H4Bu)-Bu-t (1b), 2-C6H4CF3 (1c), Bu-t (1d), Ad (Ad = adamantyl, 1e)]. The crystal structures of 1b (two diamorphic forms) and 1c featured N-H center dot center dot center dot Cl hydrogen-bonded chains. Reaction of 1a-e with the neutral face-capping, N-3 donor ligands TACN (TACN = 1,4,7-trimethyltriazacyclononane) or TPM [TPM = tris(3,5-dimethylpyrazolyl) methane] gave the corresponding six-coordinate complexes V(NR)(TACN)Cl-2 (2a-e) and V(NR)(TPM)Cl-2 (3a-e). The X-ray structures of 2b, 2c, 2d, 3b, 3c, and 3e were determined. When activated with methylaluminoxane, certain of the complexes V(NR)(TPM)Cl-2 (3) formed moderately active ethylene polymerization catalysts, whereas none of the compounds V(NR)(TACN)Cl-2 (2) were active.