Supramolecular CH⋯O, CH⋯N and CH⋯Cl interactions in metal compounds with multi-topic poly(pyrazolyl)borate ligands

Abstract

Supramolecular CH⋯O and CH⋯N hydrogen bonding interactions in metal complexes with dihydrobis(1,2,4-triazolyl)borate ( 3), hydrotris(1,2,4-triazolyl)borate ( 4) and dihydrobis(tetrazolyl)borate ligands ( 5) have been analyzed statistically and with respect to their role in determining the crystal packing arrangement. The additional ring nitrogen atoms in these modified, multi-topic poly(pyrazolyl)borate ligands are the origin of manifold CH⋯O and CH⋯N hydrogen bonds in this group of compounds. A recurrent example is the orientation of metal-coordinated triazolyl rings from 3 or 4 along the cisoid ligand(O/N)–metal-ligand(O/N) bonds because of CH⋯O/N bonding. The additional nitrogen atoms play a dual role in enhancing the acidity of the ring hydrogen atoms and serving as hydrogen-bond acceptors. In polynuclear tris(triazolyl)borate copper structures with hydrated chloride anions or chloro ligands CH⋯Cl contacts were observed.