Metal complexes as ligands. IX. Crystalline binuclear complexes containing two molecules of chloroform per complex molecule, and their unsolvated analogues

Abstract

Some new binuclear antiferromagnetic complexes of copper(11) derived from bidentate salicylaldimine ligands have been isolated with two molecules of chloroform per complex molecule. The chloroform could be driven off by heating. The chloroform-solvated complexes form as large crystals, while the unsolvated complexes are amorphous. A comparative study of the solvated and unsolvated complexes was carried out to determine the effect of the chloroform on the properties of the binuclear complex. It appears that for most properties not related to the crystal habit, the presence of the chloroform may be ignored. Thus, strong coordination of chloroform to copper atoms can be ruled out and though very weak coordination remains a possibility, it does not seem probable. The chloroform molecules may be held to the phenyl rings of the salicylaldimines by the same (weak) interaction that is known in mixtures of chloroform and benzene. The most probable mechanism of the interaction of the chloroform molecules with the complex is by weak hydrogen bonding with the two bridging salicylaldimine oxygens of the complex.