Carbonyl-molybdenum complexes of the hydrotris(3,5-dimethyl-1,2,4-triazol-1-yl) borate ligand

Abstract

The reaction of KBH 4 with 3 equiv. of 3,5-dimethyl-1,2,4-triazole at ca. 230°C yielded potassium hydrotris(3,5-dimethyl-1,2,4-triazol-1-yl) borate, K{HB(Me 2tz) 3}. The reaction of Mo(CO) 6 and K{HB(Me 2tz) 3} in N, N-dimethylformamide at 110°C gave [{HB(Me 2tz) 3}Mo(CO) 3] −, which was isolated as the salt NEt 4[{HB(Me 2tz) 3}Mo(CO) 3] ( 1). Crystal characterisation of 1 revealed a six-coordinate, distorted octahedral anion composed of a facial, tridentate HB(Me 2tz) 3 − ligand and three mutually cis (facial) carbonyl ligands. Spectroscopic data were consistent with greater electron-withdrawal by the triazolyborate ligand than by the related hydrotris(3,5-dimethylpyrazol-1-yl)borate ligand. Reaction of 1 with iodine gave {HB(Me 2tz) 3}Mo(CO) 3I, which was spectroscopi characterised as a seven-coordinate 3:3:1 face-capped octahedral complex.