Exploration of noncovalent interactions in the solid state structures of carboxylate bridged trinuclear mixed valence cobalt complexes using computational tools based on the topological analysis of the electron density

Abstract

Three linear mixed valence trinuclear cobalt(III)-cobalt(II)-cobalt(III) complexes, [CoII{(μ-L1)(μ-OOCCH3)CoIII(OOCCH3)}2]⋅4H2O (1), [CoII{(μ-L2)(μ-OOCCH3)CoIII(OOCCH3)}2]⋅4H2O (2) and [CoII{(μ-L1)(μ-OOCPh)CoIII(OOCPh)}2] (3), have been synthesized using two N2O2 donor 'reduced Schiff base' ligands, H2L1 (2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(4-chlorophenol) and H2L2 (2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(4-bromophenol), and acetate or bezoate as anionic co-ligands. The complexes have been characterized by spectroscopic measurements and their solid state structures have been determined by single crystal X-ray diffraction analysis. DFT calculations have been performed to study the mixed valence nature of the complexes. Moreover, the structure directing role of several noncovalent interactions in the solid state of the complexes has been investigated. The interactions have been characterized by a combination of two computational tools based on the topological analysis of the electron density, which are the quantum theory of atoms-in-molecules (QTAIM) and the noncovalent interaction plot, since they are useful to reveal noncovalent interactions in the solid state.