Inorg. Chem. 1987, 26, 3 124-3 134
3124
Contribution from the Department of Inorganic Chemistry, Guindy Campus, University of Madras, Madras 600 025,India
Vitamin B12and Coenzyme B12Models. 1. Synthesis and Physical Characterization of Alkyl- and (Non-alky1)cobalt(111) Complexes of 3,8-Dimethyl-5,6-benzo-4,7-diazadeca-3,7-diene-2,9-dione Dioxime V. V. Ramanujam* and V. Alexandert Received September 16, 1986 A quadridentate tetraaza ligand, 3,8-dimethyl-5,6-benzo-4,7-diazadeca-3,7-diene-2,9-dione dioxime, has been synthesized by the condensation of o-phenylenediamine with diacetyl monoxime. The free ligand is neutral and coordinates with cobalt through its nitrogen donors in the equatorial position with the loss of one of the oxime protons with the concomitant formation of an intramolecular hydrogen bond. The dichloro and dibromo complexes have been synthesized by the direct reaction of the ligand with the respective cobalt(I1) halide hexahydrate. If use is made of the axial lability of the dibromo complex [Co(DODOHbzo)Br,], pseudohalogeno complexes [YCo(DODOHbzo)Br], where Y = CN-, SCN-, or N;, Lewis base complexes [LCo(DODOHbzo)Br]A, where L = pyridine or imidazole and A = C10,- or PF,-, and the so-called cyanocobalamin models [CNCo(DODOHbzo)L]Br, where L = pyridine or imidazole, have been synthesized. Alkylcobalt(II1) complexes [RCo(DODOHbzo)L]C104, where R = C H c , C2H
