Mono and bimetallic Co III Schiff base complexes: Coordination induced ligand imidazolidine ring cleavage and stabilization

Abstract

2-(2′-Hydroxyphenyl) imidazoline ring grafted dinucleating diimine-diamine- tris-phenol ligand (H 3aeas) has been obtained from a two-step reaction of 2-hydroxy acetophenone, N, N′-bis-(2-aminoethyl)ethylenediamine and 2-hydroxy benzaldehyde. Reaction of the ligand with Co(ClO 4) 2·6H 2O and NEt 3 in MeOH–DCM solvent mixture yielded the monometallic complex [Co(aea)]ClO 4·H 2O ( 1) of imidazolidine ring hydrolyzed hexadentate proligand H 2aea. Any solvent derived MeO − bridged Co 2 complex could not be obtained due to facile cobalt coordination assisted hydrolytic cleavage of substituted imidazolidine ring. When the reaction is carried out with Co(NO 3) 2·4H 2O and CoCl 2·6H 2O in presence of NH 4NCS and NaN 3 in MeOH–DCM and MeOH under aerobic conditions, preassembly of bimetallic [Co 2( μ-OMe)] 5+ and [Co 2( μ-N 3)] 5+ cores takes place on the solvent derived methoxido and azido clips through non-hydrolytic pathways in [(SCN) 2Co 2( μ-OMe)( μ-aeas)]·DMF ( 2), and cocrystals of [(N 3) 2Co 2( μ-OMe)( μ-aeas)] ( 3a) and [(N 3) 2Co 2( μ-N 3)( μ-aeas)] ( 3b), respectively.