The synthesis and characterization of mixed derivative single phase solid solutions of divalent and trivalent metal ions

Abstract

This dissertation presents the synthesis, characterization and reactivity of layered mixed derivative solid solutions of divalent and trivalent metal phosphonates, namely the phenylphosphonate phosphite mixed derivatives of zinc and lanthanum. Layered metal phosphonates of general formula Zr(O3PR)2 where R = an organic radical such as an alkyl or aryl group, have been known since 1978. These compounds exist as two dimensional sheets of octahedrally coordinated metal atoms linked together by tetrahedral phosphonate groups with the organic portion extending away from the layer. The layers are held apart by van der Waals forces of the pendant organic groups. In the early 1980's mixed derivatives of general formula Zr(O3PR)(O3PR'), in which two different pendant groups protruded into the interlayer region, promised to have potential applications in the fields of catalysis, ion exchange, sorbants, and molecular sieves. Although analogous divalent and trivalent metal phosphonates of general formula (M^2+) or M^3+ (O3PR)[x] *yH2O have been synthesized, no mixed derivatives have been reported. The mixed derivatives, La2(O3PH)x(O3PC6H5)[3-x] *H2O and Zn(O3PH)[x-] (O3PC6H5)[1-x] *H20, represent the first single phase solid solutions of divalent and trivalent metal ions synthesized. The formation of these products demonstrates the ability to synthesize a wide variety of mixed derivatives that maintain the same basic structure with the only differences being the R and R' groups that protrude into the interlayer region. The divalent and trivalent series are particularly interesting because they also contain a coordinated water molecule that can be reversibly dehydrated. Replacement of the water molecule by intercalation of alkylamines occurs readily. All of the compounds studied have been characterized by X-ray powder diffraction, Fourier Transform Infrared Spectroscopy, Thermogravimetric Analysis and 31P MAS Nuclear Magnetic Resonance where appropriate.