We report the attempted syntheses of two photochemical dimethylsilene precursors, both of which are derived from polyphenyl silanorbornadiene skeletons. Possible synthetic schemes and our results are reported herein. Photolysis of 1,2-divinyl-1,1,2,2-tetramethyl-1,2-disilane at room temperature in a cyclohexane solution of 1,3-butadiene produces 1,1-dimethyl-2-(vinyldimethylsilylmethyl) silene which is trapped in high yields to afford the E- and Z-1,1-dimethyl-2-(vinyldimethylsilylmethyl)-3-vinyl-1-silacyclobutanes in 42 and 29% yields, respectively, along with minor amounts of 1,1-dimethyl-2-(vinyldimethylsilylmethyl)-1-silacyclohex-3-ene, 9%. Low Pressure Flow Pyrolysis at 450º C of either the E- or Z-isomer provides a relatively mild thermal source of the silene in the gas phase. Two products, 1,1,3,3-tetramethyldisilacyclohex-3-ene and 2,2,5,5-tetramethyl-2,5-disilabicyclo[2.2.1]hexane, are formed from an intramolecular rearrangement of the silene. Other reactions of the 3-vinylsilacyclobutanes include geometric isomerization, ring expansion to the silacyclohex-3-ene, and a homodienyl-1,5-hydrogen shift to 3,3,6,6-tetramethyl-3,6-disiladeca-1,4,8-triene. Synthetic schemes, successful and unsuccessful, for hydrido silene, acylpolysilene, and fluorine substituted silene precursors are discussed in the final chapter.

Raman vibrational bands are sensitive to fluctuations in the molecular environment. Variations in the bandwidth and peak position can then be utilized to monitor molecular forces and interactions present in condense phases. Nuclear Magnetic Resonance (NMR) provides a convenient probe for the study of molecular reorientation in liquids since nuclear spin relaxation times are dependent on the details of molecular motion. Presented here is the solvent study of the Raman bandwidths and frequency displacements of the mode of the compounds CH3MCI3 (M = C, Si, Ge, Sn) in a number of solvents of widely varying molecular structure. Also, a detailed isotope dilution study of the modes in CH2CI2/CD2CI2 mixtures is presented. In this set of experiments, I observed broadening of the v1 mode of CH2C12 upon dilution,which is the first experimental observation of such behavior. The temperature-dependent carbon-13 relaxation times and nuclear Overhauser enhancements in neat dichloromethane were measured. In this study we found that the molecular reorientation of this molecule was highly anisotropic, but could be well characterized assuming quasi-symmetric top behavior. In addition, in order to gain a more complete understanding of the reorientational dynamics in dichloromethane, we analyzed the 13-C NMR relaxation of CH2CI2 both in "inert" …

HPLC has been used and can quickly determine several ions simultaneously. The method of determination described for transition metals [Cr(III), Fe(III), Ni(II), Co(II), Cu(II), Zn(II), Cd(II), Mn(II)] and [Ca(II), Pb(II)] using HPLC with UV-VIS detection is better than the PAR complexation method commonly used. The effects of both eluent pH and detector wavelength were investigated. Results from using different pHs and wavelengths, optional analytical conditions for the separation of [Ni(II), Co(II), Cu(II)], [Cr(III), Fe(III), Ca(II), Ni(II), Cu(II)], and [Ca(II), Zn(II), Pb(II)] in one injection, respectively, are described. The influence of adding different concentrations of Na_2EDTA solvent to the sample is shown. Detection limits, linear range, and the comparisons between this study and a post-column PAR method are given.

The method utilizes both cation and anion concentrator columns in parallel as a preconcentration system. The preconcentrator system is loaded using a reagent delivery module operated for a specific time at a preset flow rate. Total injection volumes of 2-5 ml are routinely used. Various chromatograms are discussed along with detailed information concerning detection limits for sodium and chloride, the system operating conditions, and the solutions to other pitfalls which have arisen during the course of this work.

A variable temperature ^13 C and ^199 Hg NMR study has been conducted for diphenyl-, bis(o-tolyl)-, bis(m-tolyl)-, and bis(2, 6-xylyl)mercury in dimethyl sulfoxide and 1,1,2,2 tetrachloroethane; ^13 C T1 relaxation times are reported as a function of temperature. Barriers to rotation of the aryl rings are obtained. Chemical shifts and couplings in CDCl_3 are given for bis(p-tolyl)-, bis(2, 5-xylyl)-, bis(mesityl)-,phenyl(o-tolyl)-, phenyl(m-tolyl)mercury, and the compounds listed above. The steric interactions of these aryl mercury compounds are discussed.

When E- or Z-l-methyl-l-phenyl-2-neopentylsilene was generated by the retro-Diels-Alder vacuum-sealed tube thermolysis of its corresponding anthracene adduct, in the presence of various alkoxysilanes, only one diastereomeric adduct was formed in each case, showing that the reactions are stereospecific. An x-ray crystal structure of the methoxytriphenylsilane adduct of the E-silene confirmed its relative configuration as (R,S) or (S,R). This demonstrated that the addition of alkoxysilanes to silenes is stereospecific and syn. The relative configurations of similar alkoxysilane and alkoxystannane adducts to E- and Z-l-methyl-l-phenyl-2-neopentylsilene were assigned based on a combination of xray structures and *3C NMR data. A strong, nonbonded oxygen-metal interaction is apparent in all of those compounds studied. Treatment of the alkoxystannane adducts with alkyl lithium reagents results in tin-lithium exchange in some cases. The results indicate that the resulting <x-lithio alkoxysilanes are not configurationally stable in either THF or hydrocarbon solvents. The reaction of tert butyl lithium with a-trimethylsilylvinylmethylphenylchlorosilane in hydrocarbon solvents yields E- and Z-l-methyl-l-phenyl-2-neopentyl-2-trimethylsilylsilene. In the absence of any traps these silenes undergo a novel tert butyl lithium catalyzed rearrangement to 2-phenyl-3-trimethylsilyl-5,5-dimethyl-2-silahex-3-ene. These silenes were also trapped as their [4+2] cycloadducts with anthracene. The Z-isomer of the anthracene adduct was separated and its stereochemistry confirmed by …

The objective of this study was to synthesize new energetic, strained, saturated polycyclic compounds. For this purpose, new methodology has been developed, as follows: (i) Ketenes have been generated in situ via treatment of aldo-, keto- or alkenoic acid with either toluenesulfonyl chloride or 2-chloro-1-methylpyridfniurn iodide (Mulkaiyama's reagent). The reactive intermediates thereby generated have been found to undergo intramolecular [2+2] cycloaddition reactions in these systems.

Six bis(silyl)acetylenes with the following varied silicon substituents were prepared: I (Me, Me); II (H, H); III (Cl, H); IV (Cl, Cl); V (OMe, H); VI (OMe, OMe). While I and II may be prepared by the reaction of dilithio- or bis(bromomagnesium)-acetylide with appropriate chlorosilane, similar reactions designed to give III - VI give oligomers, YMe_2Si(C≡C-SiMe_2)_nY, VII, Y = Cl, OMe, as the major products indicating that the acetylenic functionality on silicon activates the chlorosilane toward nucleophilic substitution. Compounds III and IV were prepared by free radical chlorination of II. Methanolysis of III and IV gave quantitative yields of V and VI, respectively. In the presence of mineral acid, VI readily cyclized to give high yields of the cyclic siloxane octamethyl-4,9-dioxa-3,5,8,10-tetrasila-cyclodeca-1,6-diyne, VIII, and the analogous triyne, IX. It was determined that V and VI could be prepared directly from II in high yield by methanolysis with palladium catalyst. Vaska's complex also accomplished the conversion. I attempted to prepare bis(ethoxydimethylsilyl)acetylene by using of Wilkinson 's catalyst for hydrosilylation with acetaldehyde. The principal product of this reaction was 1-(dimethylsilyl)-3,5,5-trimethyl-4-oxa-3-silacyclopent-1-ene, XI.

The objective of this study was to synthesize and characterize new energetic polycyclic "cage" compounds. As part of a program involved in the synthesis of new polynitropolycyclic compounds, 2,6-dinitro-5-methoxy- 7-carbomethoxypentacyclo[5. 3 .0 . 0* • * . CP • i ° . 0* •8]decane has been synthesized. This is a model system which can be used to study (1) the effect of nitro substitution on the photolability of carbon-carbon double bonds and (2) to develop methods for avoiding Haller-Bauer cleavage in cage /3-keto esters when synthesizing polynitro-substituted cage compounds.