COPPER(II) BIPYRIDYL AND IMINOPYRIDYL ANALOGS OF STREPTONIGRIN

The crystal structures of (3-amino-6,6'-dimethyl-2,2'-bipyridine)dichlorocopper(II) [CuL(1)Cl(2)], and aqua[3-imido-6-(methoxycarbonyl)-2,2'-bipryidine-6'-carboxylato]copper(II), [CuL(3)(H2O)], have been determined. The complex [CuL(1)Cl(2)] crystallizes in space group Pnma with a=19.434(3), b=7.427(2). c=9.403(1) Angstrom and Z=4. The structure has been refined to a final R value of 0.057 based on 680 independent reflections. The copper(ii) centre exhibits tetrahedral co-ordination to the bipyridyl nitrogens of L(1) and two chlorine atoms. Crystals of [CuL(3)(H2O)] were grown from a solution of 3-amino-6,6'-bis(methoxycarbonyl)-2,2'-bypyridine (L(2)) and excess Cu-II The complex crystallizes in space group P2(1)/n with a=3.724(2), b=14,375(3), c=22.953(5) Angstrom, beta=90.72(3)degrees and Z=4. The structure has been refined to a final R value of 0.061 based on 944 independent reflections. The Cu-II centre is square planar with a slight tetrahedral deformation, and co-ordinates to an imino nitrogen. adjacent pyridyl nitrogen, carboxylate oxygen and a water molecule. The implications of these results on the types of complexes formed by streptonigrin are discussed.