Synthesis, Properties, and Structure of a Dinitrogen Bridged Dinuclear Hydridocobalt Complex and its Reactions with 1-Alkynes

Abstract

Dinitrogen bridged cobalt(I) hydride compounds (L3CoH)2N2(1: L = PMe32: 3L = CH3C(CH2PMe23have been synthesized by protonation of dinitrogen cobaltates. 1 crystallizes in the monoclinic space group C 2/m. a = 965, b = 1653, c = 1148 pm, ß = 106.88°, Z = 2. In solution 1 takes up N2reversibly forming CoH(N2(PMe33(la). Infrared data including isotope labeling 15N, 2H) and assignment of vN = N and vCoH bands are presented. 1 reacts with aryl alkynes to give dialkynylcobalt(III) complexes CoH(C0R1(CoR2(PMe33(5: R1 = R2 = C6H5; 6: R1 = R2 = 4-CH3C6H4; 7: R1 = R2 = 4-ClC6H4; 8: R1 = C6H5R2 = 4-ClC6H4that are also obtained in a more convenient synthesis involving cobalt(I) intermediates Co(C2R(PMe34(10: R1 = 4-CH3C6H411: R1 = 4-ClC6H4. Three metastable isomers of 5 have been characterized, the stable configuration is mer-trans as shown by a crystal structure determination: Space group P21a = 933.5(5), b = 1636.7(6), c - 901.1(3) pm, ß = 97.4(1)°, Z= 2. © 1991, Walter de Gruyter. All rights reserved.