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Research has been conducted on the methyl viologen compound crystals that contain binuclear platinum(II) polyaminocarboxylate. The use of X-ray diffraction in examining the crystals is described.

Conformational studies and structure-activity analysis were conducted on Lissoclinamide 7 and related cyclopeptide alkaloids. Results showed that a type II Beta-turn formed by the prolyloxazoline moiety and a Beta-loop segment stabilized by intramolecular hydrogen bonds at the thiazoline-D-phenylalanine-thiazoline sequence dominate the conformational preferences of the 21-membered class of Lissoclinum cyclopeptide alkaloids. Moreover, the Lissoclinum peptides' cellular toxicity decreased when the thiazolines in Lissoclinamide 7 are replaced by oxazolines.

Luminescent niobium and tantalum arylimido compounds were synthesized and characterized by X-ray crystallography and FT-Raman spectroscopy. The influences of niobium, halide atoms and neutral sigma donors on the niobium arylimido fragment as well as the vibrational modes of this unit were assessed. The implications of the results on the excited state properties of both niobium arylimido and tantalum arylimido compounds are presented.

Experiments were conducted using anthranilamides to create multiturn helical oligomers that have novel folding properties. Extended helical oligomers were constructed with the addition of pyridine-2,6-dicarboxamide and 1,3-diaminobenzene derivatives. Intramolecular hydrogen bonding and pi-pi stacking interactions were observed to stabilize the two helical structures that were formed in the solid state. It was also observed that similar structures were established in the liquid state.

Dinuclear specials with (Movsub2Osub3)super4+ cores are an intriguing family of coordination complexes of Mo(V). Photodisproportionation reactions with the tungsten analog of (Movsub2Osub3(Ssub2CN(CHsub2PH)sub2)sub4)super8 and with dinuclear tungstenocene complex ((W(etasuper5-Csub5Hsub5)sub2(CHsub3))sub2-(mu-O))super2+ were observed. It is reported that the tetraanionic thiocyanate complex (Movsub2Osub3(NCS)sub8)super4- is photosensitive, although pohotolysis results in a ligand redistribution reaction.

Single-crystal Raman measurements of the hydrated glycylglycine crystal structure indicated the orientation of the amide pi to pi* transition in the peptide plane at an angle of -46 degrees (+/- 3 degrees) to the amide carbonyl bond, while the carboxylate pi to pi* transition moment was parallel to the line connecting the carboxylate oxygens. These results were consistent with those previously obtained for the glycylglycine crystal.

The preparation of a family of novel oligomers based on the anthranilamide nucleus and its formation of pronounced secondary structural features in both the solution and solid state are described. Using 1H nuclear magnetic resonance spectroscopy and X-ray crystallographic methods, it was shown that intramolecular hydrogen bonds play a significant role in stabilizing both linear sheet and helical conformational forms. These conformational features are formed despite substitution or other structural changes into the molecules.

The treatment of bifunctional trimethylsilyl ethers/dithioethers with N3P3F6 in the presence of CsF catalysts generates five and six membered monospiroflourophosphazenes. The 31P NMR spectra of these derivatives exhibit strong dependence on ring size. The reactions of N3P3F6 with dioxanes at low temperature produce only dangling products. The five membered S-2-O and S-2-S molecules form a twist boat structure in the solid state, and their melting points are higher than those of six membered molecules. The X-ray crystallographic structures of monospiroflourophosphazenes are discussed.

Solvents, nucleophilic additives and Lewis and Bronsted acids influence the cationic pi-cyclizations of alkynyl- and alkenylcyclopentane-1,3-diones, which are mediated through BF3. Et2O. The nature of the reaction solvent affects regioselectivity, while the nucleophiles regulate the rates and selectivity of the cyclization reactions. These type of reactions are significant for the synthesis of bicyclic ring systems with different functional groups.

Various Co(0), Co(I) and Co(II) precursors undergo reduction reactions yielding the homoleptic Co(-I) isonitrile complex. X-ray crystallographic studies of the potassium Co(-I) isonitrile complex shows that the complex has discrete tetrahedral anion and cation/anion interactions. Crystal packing forces are responsible for distortions in isonitrile ligands from linear geometries. X-ray studies help determine the structure of an intermediate Co(0) complex, a dimer in the reaction pathway yielding an isonitrile complex.

An analysis of the photochemistry of a large class of oxo-bridged dimers consisting of the (Mo(super v)(sub 2)O3)4+ core, involved a study of dithiophosphate dimers (Mo2O3(S2P(OR)2)4). Unlike dithiocarbamate dimers, these dimers experience a photolysis reaction with significant wavelength dependence, in effective disappearance quantum yields. They do fail to photodisproportionate upon irradiation in visible absorption.

Low energy intramolecular dynamic behavior involving bridging for terminal oxo exchange is evident in (Mo(super v)(sub 2)O3)4+ complexes with dithiocarbamate and xanthate ligands. Energy difference between syn and anti isomers in the complexes, is negligible. The similarity of energetic parameters for oxo exchange negates the possibility of another intramolecular exchange mechanism such as dissociation of one sulfur of a dithiocarboxylate ligand to yield a species having a five-coordinate molybdenum center.

A study was done on the structural and spectroscopic manifestations of delta(MM)-pi(CC) conjugation prepared from 1, 2-W2(CCMe)2Cl2(PMe3)4. X-ray crystallography revealed an asymmetric distribution pattern of the compound and short W-C distances which are characteristic of strong delta(MM)-pi(CC) conjugation. Further studies have shown that conjugated transition-metal complexes have strong similarities with the electronic structures of analogous organic compounds.

A single crystal of Ph2PCl3 was isolated and its structure analyzed. Spectroscopic data from previous reports were then correlated with the data gathered from the study. The structure of Ph2PCl3 is trigonal bipyramidal with axial chlorines. A crystallographically imposed 2-fold axis of symmetry coincided with the P-Cl(sub eq) bond. The axial P-Cl bonds at 2.227(2) angstrom were significantly longer than the equatorial P-Cl bond at 2.011(3) angstrom. Both bond distances lie within the normal range for P-Cl bonds for similar compounds.