Thomas D. DuBois
Research Interests

Primary interests are in bonding theories and theories dealing with molecular interactions.

Early research efforts dealt with the synthesis, characterization and theoretical descriptions of the electronic absorption spectra and magnetic properties of transition metal complexes having unusual geometries. These efforts naturally included the synthesis of polydentate N, P, and As ligands and efforts to develop transition metal catalysts (both homogeneous and heterogeneous). Continuing interests in this area include the modeling of catalytic processes; especially, reactions catalyzed by the cyclopentadienyl complexes of the early transition metals.

Mid career research and teaching efforts were directed toward instrument automation using microcomputers based on the Intel microprocessors. Continuing activities in this area include the construction and applications of plasma processing equipment and instrumental methods for identifying plasma species.

Recent research efforts involve the use of computational chemistry to investigate the application of Lewis acid-base theory to a variety of systems and processes. Computational studies directed toward understanding the deposition of phosphorus nitride films from PCL₅ and NH₃, titanium nitride films from TiCl₄ and NH₃, silicon nitride from SiH₄ and NH₃, and poly-silicon films from SiH₄ are in progress. The study of the deposition of phosphorus nitride films from PCl₅ and NH₃ is part of a more general modeling study directed toward developing a detailed reaction model which explains the formation of the linear and cyclic polyphosphazenes as well as P₃N₅. The experimental characterization of the gas phase reaction intermediates and products generated by thermal means are limited to mass spectral measurements while those generated using microwave plasmas are characterized using mass spectral measurements and the emission spectra of the plasmas. The goal of this area of research is to demonstrate that gas phase reaction intermediates and/or products (cluster compounds) play a significant role in establishing film structure and quality.

Other computational studies are directed toward understanding the nature of amorphous tin(II)-tin(IV) oxides at the tin/tin oxide interface. Experimental efforts are directed toward the synthesis and characterization of sol-gels containing tin(II) and tin(IV) species in different coordination geometries. The intent is to develop sample preparation and characterization techniques which will permit the identification and study of Sn(II) and Sn(IV) centers and the interaction of these centers in amorphous tin oxides.

Additional semi-empirical and Hartree-Fock calculations are being conducted to: (1) fully model the Lewis acid-base interactions responsible for the formation of H₂SO₄ (acid rain), (2) establish the mechanistic details of a wide range of tautomeric equilibria, (3) evaluate a series of different chain initiators for the ring opening polymerization of 1,1,3,3,5,5-hexachlorocyclotriphosphazene to form linear (NPCl₂) polymers, and (4) gain a better understanding of the unusual properties of acetate bridged transition metal dimers.