Synthesis and coordination studies of [(diphenylphosphino)methyl]pyridine coordination compounds.

Abstract

The coordination properties of the bifunctional ligand 2-[(diphenylphosphino)methyl]pyridine, its two corresponding oxides, and the ligand 4-[(diphenylphosphino)methyl]pyridine towards different transition metal salts are described. The ligand 2-[(diphenylphosphino)methyl]pyridine and both of its oxide derivatives, P oxide and N,P dioxide, showed preference to behave in a chelating mode, although bridging behavior was also observed in a few cases such as when silver was the metal center involved. Unusual polymeric structures were obtained demonstrating the functionality of these ligands in the multidimensional network construction. Due to opposite positioning of its donor centers, the ligand 4-[(diphenylphosphino)methyl]pyridine showed an inclination to behave as a bridge, usually in a head-to-tail fashion, rather than as a chelate. The crystal structures were determined by single-crystal X-ray crystallography. With the use of this technique several supramolecular interactions were identified. It was demonstrated that, even though these interactions are rather weak, they play an important role in the control of the overall structure of the molecular array. The anion present and the solvent system used to grow the crystals studied herein were variables with heavy influence in the resulting molecular structures. The synthesized novel complexes were fully characterized by elemental analysis, UV-visible spectroscopy, FT-IR spectroscopy and multinuclear NMR spectroscopy, where the technique was appropriate.