PhD Thesis: Group 14 and Carborane Chemistry: from Reactive Intermediates to Materials, University of Colorado, Boulder, 2000.

Chapter 1

Oxidation of E-X bonds (E = Ge, Sn, Pb; X = R, ER₃) with CB₁₁Me₁₂* produces the CB₁₁Me₁₂^- salts of the corresponding Me₃E⁺ cations. These salts are methyl-coordinated complexes of Me₃E⁺ cations with the CB₁₁Me₁₂^- anion, with the free cation character increasing from Ge to Pb. For Si this oxidation results in methyl abstraction from the anion and formation of a novel internally charge-compensated boronium ylid CB₁₁Me₁₁, stable only below -60 deg C. By introducing solubilizing alkyl chains it is possible to obtain crystals of R₃E⁺ cations, such as n-Bu₃Sn⁺ CB₁₁Me₁₂^-, whose structure reveals a tin cation weakly coordinated to methyl groups of two CB₁₁Me₁₂^- anions in a trigonal bipyramidal fashion. Each anion is coordinated to two cations through two mutually antipodal methyl groups, thus forming infinite columns of alternating n-Bu₃Sn⁺ and CB₁₁Me₁₂^- ions with a random 2,7 and 7,2 dicoordination. Oxidation of the stannylene [(Me₃Si)₂N]₂Sn: with the 1-R-CB₁₁Me₁₁* radicals produces 1-R-CB₁₁Me ₁₁^- salts of a cyclic stannylene with an ammonium nitrogen.

Chapter 2

A bilayer photoresist based on copolymers of poly(hydroxystyrene) and tris(trimethylsilyl)silylethyl methacrylate has been developed at IBM Almadén Research Center. In an attempt to understand the reactions that occur in the photoresist film we studied the acidolysis reactions of ß-silylethyl acetates in solution. Acid-catalyzed cleavage of the model trimethylsilylethyl acetate proceeds via a nucleophilic attack on the silicon atom of the protonated acetate. Protonation of ß-tris(trimethylsilyl)silylethyl acetate is postulated to lead to a bridged siliconium cation, which reacts with nucleophiles along three pathways and yields products in which a nucleophile is attached to either a carbon or a silicon atom. This mechanism is consistent with the observed silylation and alkylation of the phenolic hydroxyl groups in the photoresist film under photolithographic conditions.

Chapter 3

An improved synthesis and a full characterization of all three 12-vertex C-hydroxydicarba-closo-dodecaboranes 1 - 3 are described. These inorganic analogues of phenols are moderately acidic, but unlike phenols, they are transparent in the near UV region and are stable to oxidation. The structure of their oxyanions 1a - 3a poses an interesting issue of a closo versus a bridged nido form. Also described is an introduction of a functionalized spacer in position 2 of 1 designed to permit incorporation into photoresists and other complex organic structures.

Chapter 4

An approach to a new family of lithium ion conducting polymers based on the lithium salts of alkylated carboranyl CB₁₁ anions is described. Preliminary results show that such materials can be made relatively easily and that they promise to provide superior solid polymer electrolytes.