From Coordination Polyhedra to Molecular Environment and Back Interplay between Coordinate and Hydrogen Bonds in Two Polymorphs of a Cobalt Complex

Two crystalline modifications of a cobalt(II) benzoate complex containing substituted pyrazole ligands are investigated. The polymorphs are characterized by different intermolecular bonding as well as by different metal-atom environments. A thorough analysis of the chemical bonding patterns by means of Bader's Atoms in Molecules theory reveals the significant role of NH center dot center dot center dot O hydrogen bonds in charge transfer within the molecule and in stabilization of unfavorable [4+1] cobalt polyhedra. Specifically, an estimation of the interaction energies according to an Espinosa correlation scheme shows the significant contribution of H bonds to the stabilization energy of the molecular conformations.