METHYLNICKEL COMPOUNDS CONTAINING BRIDGING AND MONODENTATE CARBOXYLATE LIGANDS

Dinuclear methylnickel carboxylates [NiMe(OOCR)(PMe3)]2 (R = cyclohexyl (1); CH(C6H5)2 (2); C(C6H5)3 (3); 9-anthracenyl (4); bicyclo[3.2.2]nonane-1-yl (5); C6H5 (6); 2-NH2-C6H4 (7); 4-OH-C6H4 (8); 1-naphthyl (9); 2-naphthyl (10); CF3 (11); CH2Cl (12); CHCl2 (13); CH2Br (14)) were prepared by reacting [NiMe(OMe)(PMe3)]2 and the corresponding carboxylic acid. Spectroscopic data indicate-mu-carboxylato ligands in eight-membered metallocycles (NiOCO)2, while mononuclear methylnickel carboxylates NiMe(OOCR)(PMe3)2 (1a, 2a, 4a-10a, 12a-14a) contain unidentate carboxylate anions. Upon reaction with trimethylphosphine 11 forms an ionic methylnickel complex [NiMeL4]+CF3COO- (15) rather than 11a. Compound 6 crystallizes in the monoclinic space group C2/c with a = 12.327(3), b = 12.885(4), c = 16.495(6) angstrom, beta = 102.93(2)-degrees, V = 2553(2) angstrom 3, Z = 4. Final discrepancy indices are R = 0.0631 and R(w) = 0.0659. The molecule 6 contains two square planar nickel centres (Ni-C = 1.907(7), Ni-P = 2.119(2), Ni-O = 1.955(5) and 1.919(6) angstrom) with parallel coordination planes (non-bonding Ni-Ni = 2.865(2) angstrom).