The Norman research program focuses on the synthesis and structural characterization of new classes of main-group element based compounds, inorganic polymer precursors, inorganic and organic polyamide membranes, and transition metal-phosphine complexes. Our work has included studies of: (i) phosphorus- and arsenic- nitrogen, and silicon- and germanium-phosphorus acyclic, small-ring and macrocyclic molecules; (ii) cage and macrocyclic phosphine-encapsulated metals, and (iii) carbon dioxide reduction catalysts and carrier molecules. Current emphasis is on materials with novel ligand properties that have potential as catalyst molecules and on new polymer/ceramic precursors.
Recent research has involved the synthesis and characterization of new classes of linear and cyclic phosphazanes, molecular systems based on alternating, bonded phosphorus and nitrogen atoms, and that are stabilized by novel skeletal stabilization. Linear phosphazanes, with functional molecular weight distributions, have been prepared and are under further investigation. Routes to these materials have been discovered, based on new condensation and facilitated-condensation approaches, that make use of novel skeletally-stabilized monomers. Under controlled conditions, stereoselective condensation polymerization has been uniquely achieved, a situation that has potential for development of new classes of metal-selective oligomeric and polymeric materials.
New four-, six- eight-, and twelve- membered phosphazane ring systems have been synthesized and examined with respect to their conformational and configurational structural properties. The eight- and twelve- membered skeletally-stabilized phosphazane rings contain molecular clefts or cavities that make them especially interesting as ligands and for the selective coordination of metal moieties. Coordination properties of the ligated metals are of particular interest. Since the metals are contained within molecular cavities, only very selective coordination of substrate molecules to the metal center can occur. Catalytic properties of these metal complexes, and situations where they might offer unique potential in catalyst applications is of interest in further work.
