INTERACTION OF IMIDAZOLE WITH COBALT(III) CHELATES OF TETRADENTATE DIOXIME SCHIFF-BASES

Cobalt(III) chelates of tetradentate dioxime Schiff bases [3,8-dimethyl-4,7-diazadeca-3,7-diene-2,9-dione dioxime (H2Me2en) and 3,9-dimethyl-4,8-diazaundeca-3,8-diene-2,10-dione dioxime (H2Me2pn)] of the type [Co(HL)Br2] (H2L = H2Me2en, H2Me2pn) when reacted with imidazole (or substituted imidazole) in the presence of NaClO4 in MeOH yield stable, six-coordinated, diamagnetic cobalt(III) complexes [Co(HL)(B)2](C104)2 (B = Im, MeIm, EtIm, ViIm, AlIm). In these complexes, the tetradentate ligands are bound in their deprotonated, monoanionic form giving an intramolecular hydrogen-bridge. The complexes are 1:2 electrolytes and are characterized by electronic, IR and NMR (H-1 and C-13) spectra and polarographic measurements.