Influence of the Lewis basicity hardness of crystallization solvents on the coordination sphere of the complex [Co(3,5-dinitrobenzoate-O,O′)2]: crystallographic and theoretical analysis

Complex [Co(DNB)(2)] was recrystallized in water (H2O), methanol (CH3OH), ethanol : acetone (EtOH : Act), dimethyl sulfoxide (DMSO), acetone (Act), and acetonitrile (ACN). As a result, mono or trinuclear molecules were obtained depending on the solvent used. A combination of X-ray crystallography and DFT calculations demonstrated that this behavior is guided by a mixture of the closeness of the HOMOs of the solvents to the SOMOs of the Co(ii) ions and the possibility to build intermolecular hydrogen bonds between the carboxylate group of the DNB ligands and the solvent. This conclusion is supported by the calculated energy of crystallization which reveals evidence that this process is thermodynamically controlled. As a consequence, the crystallizations in H2O, CH3OH, EtOH : Act, and DMSO produce mononuclear complexes, while Act and ACN induce the formation of trinuclear species.

Automated summary

This study investigated the recrystallization of complex [Co(DNB)(2)] in different solvents and found that mono or trinuclear molecules can be obtained depending on the solvent used. X-ray crystallography and DFT calculations revealed that this behavior is influenced by the closeness of the solvents' HOMOs to the Co(ii) ions' SOMOs and the formation of intermolecular hydrogen bonds between the carboxylate group of the ligands and the solvent.