INTRAMOLECULARLY ALKYLATED SALEN COMPLEXES - NEW MODELS FOR COENZYME B-12 WITH A COBALT-TO-LIGAND CARBON BRIDGE

The synthesis of H-2salen -[ethane-1,2-diylbis(nitrilomethylidyne)]dip henol} derived models 1 for coenzyme B-12 with a carbon bridge between the ligand and cobalt has been accomplished by condensation of salicy laldehyde and omega-substituted 1,2-diamines 8 followed by complexatio n with Co(II), reduction to Co(I) complexes, and intramolecular alkyla tion. The structures of intramolecularly alkylated Co(salen) complexes with a bridge of three, lb, and of four methylene groups, lc, have be en investigated by NMR spectroscopy and determined by X-ray crystallog raphy.