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The mechanisms of the hydrosilylation reactions of unsaturated compounds with the tungsten complexes are examined by using the density functional theory method. The results have shown that the hydrosilylation of acetone has proceeded through a metal hydride migration, while the hydrosilylation of nitrile has occurred through a silyl migration mechanism.

The results on the experimental and computational studies of the hydrogen-bond-promoted enantioselective hetero-Diels-Alder reaction of Danishefsky's diene with benzaldehyde are reported. The results indicate that carbonyl group of benzaldehyde is activated by forming an intermolecular hydrogen bond with one of the hydroxyl groups of the alpha,alpha,alpha',alpha'-tetraaryl-1,3-dioxolane-4,5-dimethanol molecule.

The transient organoindium intermediates formed in the reaction of proparpyl bromide with indium in aqueous media and tetrahydrofuran is examined by NMR spectroscopy and found to be allenylindium (I) and allenylindium (III) dibromide. The results suggest that computational methods may be helpful in the understanding of these organometallic reactions in aqueous media.

Using NMR, IR, and CD spectroscopy, the conformational properties of peptides 1 - 10 of beta (super 3)-aminoxy acids having different side chains on the beta carbon atoms are investigated. Theoretical studies on series of model diamides rationalize very well the experimentally observed conformational features of these beta (super 3)-aminoxy acids.

The conformational studies of linear peptides, which contain a D,L-alpha-aminoxy acid dimer segment are reported. The findings indicate that A D,L-alpha-aminoxy acid dimer could form two homochiral N-O turns, with the backbone folding into an extended helical structure.

Research suggests that photolysis of a complex of magnesium and o-, m-, and p-C(sub)6H(sub)4F(sub)2 yields distonic o-, m-, and p-benzyne radical cations with an energy consumption within 2.2 eV. Data indicate that the formation of the o-benzyne cation is most facile.

Research has been conducted on the chiral alpha-aminoxy acids of different side chains. The synthesis of these acids has been carried out with high purity starting with the chiral alpha-amino acids and the results are presented.

Research has been conducted on the inverse-electron demand Diels-Alder reaction between 1,3,5-triazine as a diene and 2-aminopyrrole as a dienophile. The theoretical study of this reaction which leads to the cascade reaction for the purine analogue one-pot synthesis is described.

Alkyne addition to molybdenum alkylidenes is investigated with regard to alpha and beta addition preferences.

It has been possible to identify the preferences for beta-strand, 2(sub 7)-ribbon, 3(sub 10)-helix, and alpha-helix formation for a series of polyglycine models up to 14 amino acid residues. It was found that there is a significant cooperativity for the formation of the 3(sub 10)- and alpha-helices.

Research has been conducted on the fluoride and chloride anion-binding properties of calix[4]pyrrole. The density functional theory calculations have been used to investigate the conformational preference of calix[4]pyrrole and its properties.

Research was conducted to examine the key conformations of beta-dipeptide models using quantum mechanics calculations including a self-consistent isodensity solvation model. The isodensity solvation model was employed to investigate the tendency of beta-sheet, 14-helix and 12-helix formation of beta-peptide models. Results indicate somewhat stronger hydrogen bonding in the 12-helix than in the 14-helix structure.

Research was conducted to investigate the selectivities of nucleophilic additions of ethyl, vinyl and ethynyllithium and Grignard reagents to a 2-(3'-phenylpropyl)cycloheptanone. Theoretical examinations as well as quantum mechanical calculations were conducted on the additions of hydride and ethynyllithium reagents and the HLi additions to cycloheptanones, respectively. Results indicate higher selectivity upon an increase in the size of the nucleophile.

A study was conducted to characterize the geometry, tautomerism, isomerism and stability of porphyrin isomers. Twenty seven structures based on E/Z-configurations and NH tautomerism were analyzed in the study. Computations were carried out using a Pople Gaussian 92 DFT program. Results indicated a rapid interconversion between two anti tautomers. Findings also suggested that the rate of exchange was sensitive to both temperature and isotopic substitutions.

Ab initio molecular orbital and density functional techniques were utilized to characterize the kinetics involved in the addition of ethene to molybdenum alkylidenes and the properties of the alkoxide ligands. Ab initio analysis of the energetics involved in the addition of Mo(NH)(CHR)(OR')2 and ethene indicated the presence of electron-withdrawing alkoxide ligands that inhibited Mo=C rotation. Furthermore, agostic interaction in the syn rotamer mediated the stability of the molybdenum alkylidenes.

The substituent effects on the O-CH3 and O-H bond dissociation energies of 18 para-substituted phenols and 11 para-substituted anisoles were investigated in terms of the ground-state effects and the stabilities of the phenol, anisole and phenoxy radicals. The results, which were obtained using density functional theory, showed a relationship between the radical effects and differences in charge and spin density of the phenoxy radical in support of the concept that the phenoxy radical's stability depends on polar and spin delocalization effects.

The mechanism of the decomposition of tetraalkyl titanium complexes was investigated using unimolecular and bimolecular methane elimination reactions based on an ab initio molecular orbital theory. Calculations of total energies, thermal energies, entropies, transition structures and reaction products revealed an intrinsic preference for alpha-hydrogen abstraction over gamma-hydrogen abstraction. The presence of bulky alkyl groups further increased the preference for alpha-hydrogen abstraction.

A theoretical study was performed on the reaction of 2-silylthiazole with formaldehyde and a termolecular mechanism for the reaction was generated by ab initio calculations. The mechanism predicts the low activation energy of one molecule of 2-silylthiazole and two molecules of formaldehyde. The rection starts with the formation of the N-(siloxymethyl)thiazolium ylide followed by the formation of another intermediate by a nucleophilic addition to a second molecule of aldehyde. 1,6-Silyl migration of the immediate intermediate and the loss of a molecule of aldehyde give the final product.

The density functional method estimates the bond dissociation energies (BDE) of the benzylic C-H bond for a set of para-substituted toluene compounds, and substitution effect on the BDE. The spin delocalization from the benzylic radical center due to the para electron-donating and electron-withdrawing groups, decreases the BDE of the C-H bond. The ground state and radical effect have contributions to the C-H BDE. An electron-donating group in the para position stabilizes the radical and destabilizes the ground state. For an electron withdrawing group, the benzyl radical is stabilized more than the ground state.

Density functional analysis of Ti(O-CH2-CH2-O)(O-O-Me)(O-CH2-CH=CH2)(H2O) has been performed to model the dimeric process of Sharpless epoxidation. The titanium center exhibits a distorted octahedral conformation and the Ti-O-O unitshow an eta2 structure. The activation energies determined by HW3 basis set are consistent with the experimentally observed values. The Ti-O-O unit reaches the C-C double bond in a spiral manner, with two C---O bonds gauche to Ti-O(sub water) bond in the presence of tert-butyl peroxide oxidant.