Syntheses, crystal structures, and genotoxic studies of cis-µ-1,2-peroxo dicobalt(III) complexes

Abstract

Two peroxo-bridged dinuclear Co(III) complexes, {[Co2(ea)2(Phen)2(O2)]·5.5H2O·2Cl} (1) and {[Co2(ea)2(Bipy)2(O2)]·2H2O·2NO3} (2) (Hea = ethanolamine, Phen = 1,10-phenanthroline, Bipy = 2,2′-bipyridine), are prepared by reaction of CoCl2·6H2O or Co(NO3)2·6H2O with Hea in the presence of an α-diimine (Phen or Bipy) under reflux. The complexes have been characterized by IR, NMR, thermal gravimetric analysis, cyclic voltammetric (CV), powder X-ray diffraction, and single-crystal XRD techniques. Single-crystal X-ray crystallographic investigations of 1 and 2 reveal that each Co(III) is coordinated by one deprotonated ethanolamine and an α-diimine chelate. The remaining coordination sites of the metal ions are satisfied by bridging peroxide (O22−) in a cis-μ-1,2 manner. The distances [O–O = 1.487(6) (1) and 1.462(3) Å (2) and Co⋯Co = 2.731(12) (1) and 2.7426(6) Å (2)] support the peroxo bridging in a cis manner in both complexes. The crystal lattice is consolidated via extensive H-bonding and π‒π interactions to form a 3-D supramolecular architecture. Thermal data are consistent with the proposed stoichiometry and presence of lattice water. The CV studies of 1 indicate the presence of a quasi-reversible redox couple (CoIII‒CoIII/CoII‒CoII) in solution. Genotoxic studies are also performed on 1 to investigate the possible applications and side effects of the compounds in medicine.