University of Missouri - Saint Louis

The Graduate School

Announcement

An oral examination in defense of the dissertation for the degree

Doctor of Philosophy in Chemistry

Ngamjit Praingam
M.A. in Applied analytical and inorganic chemistry, April, 1998, Mahidol University, Thailand.
B.A. in Chemistry, May, 1994, Mahidol University, Thailand.

Abstract

The activation of a Si-H bond of a hydrosilane by platinum phosphine complexes can produce a variety of PtSi containing complexes depending on the nature of the hydrosilane and the phosphine. The hydrosilanes examined in this study included 9,9-dihydrosilafluorene (H2SiC12H8, 1) and 3,7-di-tert-butyl-9,9-dihydrosilafluorene (H2SiC20H24, 2) both of which have the silicon center incorporated into a constrained tricyclic ring. These hydrosilanes were chosen for the study since it was anticipated that they would show enhanced reactivity in Si-H bond activation reactions due to the reduced steric demands of the planar tricyclic ring system compared to the parent diarylsilane, Ph2SiH2. The substituted silafluorene (2) was studied to determine if addition of a bulky tert-butyl group attached to the dibenzo-rings of the silafluorene would influence the type of product formed. A variety of different platinum phosphine complexes were examined to determine if the nature of the phosphine affected the reactivity of the platinum phosphine precursor with the hydrosilanes (1-2). The phosphines chosen differed in their denticity (monodentate vs. bidentate), steric demand (as determined by the Tolman cone angle), and electronic effects (as determined by the basicity of the free phosphine). The phosphine platinum complexes examined in this study included a series of small to large phosphines including both monodentate and bidentate phosphines with varying basicities: (Me3P)2Pt(CH3)2, (Me2P(CH2)2PMe2)PtMe2, (R3P)3Pt (R = Et or n-Pr), (Ph2P(CH2)nPPh2)PtMe2 (n= 2-3), (Me2N(CH2)2PPh2)PtMe2, (Ph3P)2PtMe2, (Cy3P)2Pt(CH3)2, and (tBu3P)2Pt. A number of novel complexes were produced in the study and included four- and six-coordinate Pt environments as well as monometallic, dimetallic, and trimetallic Pt-Si products. The Pt-Si containing products were characterized by multinuclear NMR spectroscopy, IR spectroscopy, and when possible, X-ray structural determinations and elemental analysis.

Defense of Dissertation Committee