9408455 Hoffmann Cornell University In this research, supported by the NSF Theoretical and Computational Chemistry Program, extended Huckel theory is applied to treat: (1) transition metal carbides, borides, and silicides, (2) activation of CH and HH bonds by Rhodium porphyrin complexes, (3) tetrahedral and square-planar networks of main group and transition metal elements, (4) enzyme-catalyzed oxidation of methane to methanol, and (5) novel, super-hard materials consisting of interpenetrating diamond-like nets. Some speculative new bonding concepts based on generalized orbital populations will be explored. Huckel theory has its origin in the fundamentally correct laws of molecular quantum mechanics, but drastic approximations are made to simplify the computations so that it becomes feasible to apply these methods to molecular systems much too large to be treated by the more rigorous ab initio theories. When judiciously applied, extended Huckel theory has proved to provide reliable predictions of chemical structures and insight into the principles of chemical bonding. In this research project Huckel theory is applied to a broad range of chemical problems directed toward the discovery of new materials with unusual physical and chemical properties and a deeper understanding of the chemical principles which govern these properties.
