Synthesis And Characterization Of Polydental Pyridylphosphine Ligands And Their Complexes

In the last decade, the design and synthesis of polydental ligands for the construction of linear metal chain complexes have attracted considerable attention due to the unique polynuclear metal-metal bonding, properties, and potential application as molecular wires and in catalysis. Compared to pyridylamino ligands containing N atoms only, two classes of polydental ligands---polyphosphines and pyridylphosphines are also widely used to synthesize linear transition metal complexes. The former can stabilize transition metals at low oxidation states and the latter adapts to construct polynuclear heterometallic metal chains. However, there are a limited number of polydental pyridylphosphine ligands, especially long chain pyridylphosphines, to have been developed and used to prepare polynuclear linear metal complexes in recent years. Using "one–pot"synthetic method developed in our laboratory, raw material 2-chloro-6-diphenylphosphinopyridine and pentadental pyridylphosphine di[2-(6-diphenyl-phosphino)pyridyl]phenylphosphine (P₃N₂) were conveniently prepared in moderate yield and fully characterized. The preparation of a long chain pyridylphosphines bis[2-(6-diphenylphosphino-pyridyl)phenylphosphino]methane (P₄N₂) was also presented. This new ligand was characterized with NMR spectra and mass spectra. There were two isomers for this product, as identified by 1H-, 31P-NMR spectra. In order to study self-assembly of polynuclear complexes and the metal-metal bonding between high-valent transition metals and metal ions with d1-10 electronic configurations, a reaction of trans-Pd(PhPPy₂)₂Cl₂ with [Cu(CH₃CN)₄]ClO₄ leads to a new heterobinuclear complex [(PhPPy₂)₂PdCuCl₂]ClO₄, not expected polynuclear complex. The structure of this complex was determined by X-ray crystallography, in which PhPPy2 exhibits a new coordination mode. In this coordination code, it is possible for metal linear complexes to be synthesized through self-assembly. At room temperature the complex is photoluminescent in solution. The coordination ability of two long chain pyridylphosphines P3N2,P4N2 and low-valent d10 transition metal ions Cu(I),Ag(I),Au(I) was discussed. During this work, two gold(I) complexes were obtained unexpectedly. Their structures were measured by single crystal X-ray crystallography, and photoluminescent properties were investigated at the same time.