Synthesis, characterization, and fluxional behavior in solution of the salts Et₄N⁺[Me₂Ga(N₂C₅H₇)(OCH₂CH₂X)]M(CO)₃⁻ (where N₂C₅H₇ = 3,5-dimethylpyrazolyl, X = NMe₂ or SEt, and M = Cr, Mo, or W). X-Ray crystal structure of the W complex with X = NMe₂

Abstract

. Can. J. Chem. 68, 109 (1990). The tricarbonyl anions of Cr, Mo, and W incorporating unsymmetrical tridentate chelating pyrazolyl gallate ligands, [Me2Ga(N2C5H7)(0CH2CH2X)]M(C0)3-, have been isolated as their crystalline E~~N + salts. 'H nmr and solution infrared studies indicate that the octahedral anions display a facial arrangement of the gallate ligand and the three carbonyl groups. This stereochemistry has been proven definitively for the tungsten complex with X = NMe2 by an X-ray structure determination (see below). Fluxional behavior for the anions in d6-acetone solution has been demonstrated by variable temperature 'H nrnr studies and is compared to similar behavior displayed by the neutral molybdenum "allyl" complex, [Me2Ga- Mots ~1 . 4~ : complexes gallate de pyrazole, comportement fluxionnel des complexes Ga-W, structure cristalline d'une complexe Ga-W, complexes Ga-W.[Traduit par la revue]