HYDROGEN BONDS IN THE FORMATION OF COPPER(II) 1,10-PHENANTHROLINE HYDROXYCARBOXYLATOGERMANATE CRYSTALS USING HIRSHFELD SURFACE ANALYSIS

This article is dedicated to the investigation of crystalline structure in the complex cation-anionic compounds Cu(Phen)2Cl]2[Ge(HCit)2]⋅6H2O (I), [Cu(Phen)3]2[Ge2(OH)(HTart)(μ-Tart)2]·11H2O (II), [CuCl(Phen)2]4[{Ge2(OH)2(μ-Tart)2}Cl2]·4Н2О (III), [Cu(Phen)3]2[(OH)2Ge2(μ-HXylar)4Ge2(μ-OH)2]·8H2O (IV), [CuCl(Phen)2]4[(OH)2Ge2(μ-HXylar)4Ge2(μ-OH)2]·8H2O (V) using Hirshfeld surface analysis. This method has showed itself as an effective tool for analysis of intermolecular interactions, such as hydrogen bonds or weaker C…H and С…Н…p connections. Three-dimensional picture of close interactions in the crystal was built for each of the compounds I–V, where short connections are red-colored, while others – weaker and shorter – are light areas and small spots. It was established that in the structures of all compounds different types of hydrogen bonds are presented: bifurcate connections, symmetrical О-Н…О, С-Н…С and asymmetrical ones with water molecules. Two-dimensional histograms – 2D-fingerprint plots, allowed to evaluate quantitively connections in the crystals and establish that H…O/O…H and H…H interactions make the biggest contribution to the total surface area. The presence of the big number of crystallization water molecules is determinant for the formation of complex system of hydrogen bonds and strengthening of the structure, that otherwise would be unstable because of the big size of cations and anions. Due to the fact, that all compounds have the same complexing agent Ge(IV), structure of the anion is determined by polydentate ligand. Obtained results are important for the further development of the water role in the processes of crystallization, crystal formation, electrical dissociation and, especially, dissolving of coordination compounds in biological systems.