Disruption of "Coordination Polymer" Architecture in Cu2+ Bis-Phosphonates and Carboxyphosphonates by Use of 2,2 '-Bipyridine as Auxiliary Ligand: Structural Variability and Topological Analysis
Abstract
The outcome of a synthesis involving a metal ion and a (poly)phosphonic acid depends on a plethora of variables such as solution pH, reactant molar ratios, nature of the metal ion, number of phosphonate groups, and other "functional" moieties present on the ligand backbone. Products are usually coordination polymers of diverse dimensionality.
Here we report that the use of a chelating auxiliary ligand (2,2'-bpy) can "disrupt" the polymeric architecture of the copper phosphonate, causing the isolation of a series of molecular complexes (mononuclear or binuclear) that incorporate both the phosphonate and the 2,2'-bpy ligands. Synthetic details, crystal structures, and intermolecular interactions (pi-pi stacking and hydrogen bonding) are discussed.
The structures of the obtained Cu complexes are extended into 2D or 3D networks via multiple hydrogen bonds involving the molecular units and crystallization water molecules. These H-bonded networks have been classified from the topological viewpoint, revealing diverse topologies that also include their undocumented types.