Methyl, benzyl and pseudo-halogeno cobalt(III) complexes of a novel dioxime containing a crown ether moiety

Abstract

A new quadridentate ligand, 3,8-dimethyl-5,6-benzo(15-crown-5)-4,7-diazadeca-3,7-diene-2,9-dione dioxime (H₂L) has been synthesized by the reaction of 4',5'-diaminobenzo (15-crown-5) with diacetyl monoxime. The dibromo complexes of this ligand [Co(HL) Br₂) have been prepared by the direct reaction of H₂L with CoBr₂. 6H₂O. Pseudo-halogeno complexes

[XCo(HL)Br], where X-CN^-, SCN^-, N₃^-. or Lewis base complexes [LCo(HL) Br]CLO₄, and L pyridine, have been synthesized as a result of the axial lability of [Co(HL)Br₂] . Alkyl and benzyl cobalt(III) complexes [R Co(HL₁) L], R Me or PhCH₂ have been prepared by the oxidative-addition reaction of the <i>in situ </i>generated Co(I) form of [Co(HL)Br₂] complex with MeI or PhCH₂Br and a Lewis base in inert condition. In addition, the heterodinuclear complex containing the oxime to dianion as bridging ligand and 2,2'-bipyridine (L') as end-capping ligand has been synthesized by using [Ni(HL)]ClO₄ as the

ligand for the MLⁿ⁺ center. The structures of the dioxime and its complexes are proposed on the basis of elemetal analyses,¹H and ¹³C NMR, IR and MS spectral data.