ALKYLCOBALT CHELATES WITH SCHIFF-BASES DERIVED FROM A BETA-DIKETONE BEARING BOTH ALKYL AND ARYL GROUPS

Organocobalt(III) complexes with Schiff bases derived from a beta-dike tone bearing both an alkyl and an aryl group have been prepared. The t emplate syntheses using benzoylacetone and ethylenediamine as complexi ng agents provide a route to alkylcobalt chelates with the correspondi ng tri- and tetradentate Schiff bases. However, if a beta-diketone wit h two aryl groups, e.g, dibenzoylmethane, was employed as the starting ketoenol component, no organometallic products were detected; a new m ixed-ligand 'inorganic' chelate of cobalt(II), [Co{O=C(Ph)CH=C(Ph)O}(2 )(en)], was isolated instead. Its structure as well as that of one of the alkylcobalt complexes with a tridentate Schiff base composed of be nzoylacetone and ethylenediamine have been established by X-ray techni ques. The current scope of the template synthesis of alkylcobalt compl exes with Schiff bases is summarized. (C) 1998 Elsevier Science S.A.