Part I. Diels-Alder cycloadditions of 1,2,3,4,9,9-hexachloro-1α,4α,4aα,8aβ-tetrahydro-l,4-methanonaphthalene (32) and 1,2,3,4,9,9-hexachloro-lα,4α,6,7- tetrahydro-l,4-methanonaphthalene (33) to 4-methyl- and 4-phenyl-l,2,4-triazoline-3,5-dione [MTAD and PTAD, respectively] and to N-methylmaleimide (NMM) have been studied. The structures of several of the resulting cycloadducts were determined by X-ray crystallographic methods. The observed stereoselectivity of each of these Diels-Alder reactions was further investigated via application of theoretical methods. Thus, semiempirical (AMI) and ab initio molecular orbital calculations were used to calculate relative energies. Ab initio calculations were employed to perform frontier molecular orbital analyses of diene-dienophile interactions.

The focus of this research is to explore the molecular-level interactions between reactive metal surfaces and aqueous environments by combined ultra-high vacuum/electrochemistry (UHV-EC) methodology. The objectives of this work are to understand (1) the effects of sulfate ions on the passivity of metal oxide/hydroxide surface layer, (2) the effects of sulfur-modification on the evolution of metal oxide/hydroxide surface layer, and (3) the effects of sulfur adsorbate on cation adsorption at metal surfaces.

The purpose of this study was to determine the factors affecting the acid degradation of chrysotile asbestos (Mg_3Si_2O_5(OH_4)) . Millions of tons of asbestos have found use in this country as insulative or ablative material. More than 95 percent of the asbestos in use is of the chrysotile variety. The remaining 5 percent is composed of various types of fibrous amphiboles. The inhalation of asbestos can lead to several diseases in humans. Asbestosis, lung cancer and mesothelioma are the most common afflictions associated with asbestos inhalation, and they may occur up to 40 years after the initial exposure. It has previously been reported that if more than 50 percent of the magnesium is removed from a chrysotile sample its carcinogenicity is reduced to nil. Several inorganic acids were studied to determine their ability to leach magnesium from chrysotile. It was found that the ability to leach magnesium was dependent upon the acidic anion in addition to the concentration of the acid. The ordering of the efficiency of the acids in their ability to remove magnesium from chrysotile was found to be HCl > H_2SO_4 > H_3PO_4 > HNO_3. Predictive equations were developed to allow the calculation of the amount of …

The purpose of this dissertation is to investigate the behavior of polycyclic aromatic hydrocarbons (PAHs) in binary solvent systems and determine and/or develop predictive mathematical expressions for describing solutions in which hydrogen-bonding occurs.

The tricobalt cluster PhCCo₃(CO)₉ (1) reacts with the bidentate phosphine ligand 2,3-bis(diphenylphosphino)maleic thioanhydride (bta) with added Me₃NO to yield PhCCo₃(CO)₇(bta) (2), which upon heating overnight yields Co₃(CO)₆(μ₂-η²,η¹-C(Ph)C=C(PPH₂)C(O)SC(O)) (μ₂-PPh₂) (3). Cluster (3) has been isolated and characterized by FT-IR and ³¹P NMR spectroscopy. Structural determination of the cluster has been demonstrated by X-ray diffraction analysis. Cluster (3) is analogous to the cluster synthesized by Richmond and coworkers. The redox properties of (3) have been examined by cyclic voltammetry and the data are reported within.

Reaction of the tetracobalt cluster Co4(CO)10(t 4-PPh)2 with 1,2-bis(dimethylphosphino)ethane (dmpe) affords the bis-substituted cluster Co4(CO)8(dmpe)(t 4-PPh)2. The bidentate dmpe ligand is shown to bind to the cluster in a chelating fashion by IR, NMR, and X-ray diffractions analyses. The fluxional nature of the ancillary carbonyl groups has been studied by variable temperature 13C NMR measurements which reveal two distinct carbonyl scrambling pathways. The stability of the phosphine-ligated cluster has been examined using in situ Cylindrical Internal Reflection (CIR) Spectroscopy. The effect of the dmpe ligand on the cluster polyhedron will be discussed with respect to the observed crystallographic and spectroscopic results

Diels-Alder [4+2] cycloaddition of a mixture of 1- and 2 methylcyclopentadiene to 2-phenyl-g.-benzoquinone affords a mixture of four nd cycloadducts. A single, isomerically pure cycloadduct was isolated by careful column chromatography. Stereospecific reduction of this material with sodium borohydride and cerium(III) chloride 'affords a single, isomerically pure tricyclic diol. The structures of the cycloadduct and this tricyclic diol, established via analysis of their one- and two-dimensionial NMR spectra, were shown to be (1-methyl-5-phenyltricyclo[6.2.1.02,7]undec a-4,9 diene-3,6-dione and 1-methyl-5-phenyltricyclo[6.2.1.0 2 ,7 ]undeca-4,9-diene t.&A-3-=.a-6-diol), respectively. Intramolecular [2+2] photocyclization of this tricyclic diol afforded the corresponding cage diol, 3-methyl-7phenylpentacyclo[5.4.0.0 2 ,6 .03 , 1 0 .05, 9 ]undecane-.exogxa-8,11-diol. Oxidation of this cage diol with pyridinium chlorochromate in dry dichloromethane afforded a single, isomerically pure cage hydroxyketone, 3-methyl-7 phenylpentacyclo[5.4.02,6.03,l .1519]undecane-xA-8-ol-II-one, whose structure was established by single crystal X-ray crystallographic methods.

Evidence is reported for the formation of carbon-containing contamination products at the copper-tungsten (Cu-W) interface during the metal organic chemical vapor deposition (MOCVD) of copper on tungsten. Cu(II)bishexafluoroacetylacetonate [Cu(hfac)_2] was physisorbed onto lightly oxidized tungsten (WO_x) at 115K, under ultra-high vacuum conditions, and then annealed sequentially to higher temperatures. Copper reduction was observed by 320K. Carbonaceous and carbidic contamination of the WO_x surface was observed, even after sample warming to 625K in UHV. The results indicate that low temperature MOCVD of Cu may be possible, but interfacial contamination from the organic ligand fragmentation is a major concern.

Diels-Alder cycloaddition of methylcyclopentadienes to 2,5-dibromo-p-benzoquinone was performed. A single, isomerically pure cycloadduct was isolated, whose structure was assigned via analysis of its 1-D and 2-D NMR spectra. Diels-Alder cycloaddition of methylcyclopentadienes to 2 -methoxy-p-benzoquinone was performed. A single, isomerically pure cycloadduct was isolated, whose structure was assigned via analysis of the 1-D and 2-D NMR spectra of this cycloadduct and its reduction product obtained via stereo-specific reduction with sodium borohydride in the presence of cerous chloride. The structure of Thiele's ester was assigned via analysis of its 1-D and 2-D NMR spectra.

The chemistry of transition metal clusters has been a fast developing area of organometallic research in recent years. Compared to mononuclear metal complexes, polynuclear clusters offer more opportunities to study cooperative effects and electron reservoir properties between contiguous metal centers, in addition to functioning as storehouses for the release of catalytically active small fragments capable of exhibiting heterosite subtrate activation. Theoretically, metal clusters are intermediates between mononuclear complexes and metal surfaces, i.e., they serve as a bridge between molecular and solid-state chemistry. Transition metal clusters are ideal candidates to study M-M interactions stretching from the single bond to the collective metallic behavior found in a three-dimensional network of metal atoms. The reaction between the redox-active diphoshpine ligand bpcd and RU(CO) has been examined under a variety of conditions. The disubstituted cluster Ru3(CO)10(bpcd)(2) has been synthesized and shown to contain a chealating bpcd ligand, on the basis of IR and 31P NMR data. The cluster 2 (chelating isomer) undergoes cluster fragmentation at ambient temperatures in the dark to give the binuclear compound 3 and Ru3(CO)12, with no evidence for the formation of 4. Both 3 and 4 have been isolated and fully characterized in solution by IR and NMR spectroscopy, and …

Detection, identification and separation of polycyclic aromatic compounds in environmental samples are of extreme importance since many of these compounds are well known for their potential carcinogenic and/or mutagenic activities. Selective quenching of molecular fluorescence can be utilized effectively to analyze mixtures containing different polycyclic aromatic hydrocarbons. Molecularly organized assemblies are used widely in detection and separation of these compounds mainly because of less toxicity and enhanced solubilization capabilities associated with these media. Feasibility of using nitromethane and the alkylpyridinium cation as selective fluorescence quenching agents for discriminating between alternant versus nonalternant polycyclic aromatic hydrocarbons (PAHs) is critically examined in several molecularly organized micellar solvent media. Fluorescence quenching is used to probe the structural features in mixed micelles containing the various combinations of anionic, cationic, nonionic and zwitterionic surfactants. Experimental results provide valuable information regarding molecular interactions between the dissimilar surfactants.

Gas phase kinetics and thermochemistry of several halogenated species relevant to atmospheric, combustion and plasma chemistry were studied using experimental and ab initio theoretical techniques.

The preparation of layered double hydroxides via titration with sodium hydroxide was thoroughly investigated for a number of M(II)/M(III) combinations. These titration curves were examined and used to calculate nominal solubility product constants and other thermodynamic quantities for the various LDH chloride systems.

Tensile properties, namely the elastic modulus, tensile strength, percent of elongation at yield and at the break were determined for the pure components and blends. The results are connected to the respective phase diagrams and demonstrate that blending makes property manipulation possible. Blends for which the mechanical properties are better than those of pure EPs can be obtained.

Extended Hückel methods are known to be a useful tool in understanding surface phenomena. Important quantities about atoms and chemical bonds can be obtained from this computationally simple method, although caution must be exercised in interpreting the results. Application of Extended Hückel calculations to large metal clusters reveals the role of d orbitals in solids. Basic ideas of constructing model compounds have been developed. Several model systems for surface chemisorption processes are constructed in order to understand the surface catalyzed oxidative degradation of polyperfluoroethers. The activation of oxygen molecules can be explained. The Lewis acid character of the iron fluoride surface can be predicted. Based on these results, mechanisms of the degradation processes are discussed.

One- and two-dimensional NMR spectroscopy, including 13C{6Li}{1H} triple resonance techniques, were used to characterize a series of mixed alkyllithium aggregates and to study their exchange processes.

I. Reductive dimerization of pentacyclo[5.4.0.0.^2,6.0^3,10.0^5'9]undecane-8-one-(PCU-8-one, 53) affords a mixture of meso and d,l pinacols (55a and 55b respectively). Acid promoted rearrangement of 55a and 55b conceivably can proceed with migration of C(7)-C(8) and/or C(8)-C(9) to form the corresponding pinacolone(s). In our hands, acid promoted rearrangement of 55a and 55b each proceeds with exclusive migration of C(7)- C(8) bond, thereby affording 58a and 59a respectively. Mechanistic features of this rearrangement are discussed. II. 4,7,1 l-trimethylpentacyclo[6.3.0.0.^2,6.0^3,l0.0^5,9]undecane-exo-4,exo-7-diol (23a) was successfully synthesized. This diol crystallizes in a helical tubuland lattice although its molecular structure does not possess C2 rotational symmetry.

Detection of ultratrace levels of metallic ion impurities in hydrofluoric acid solutions and alkaline hydrogen peroxide solution was demonstrated using a silicon-based sensing electrode. The sensor's operation principle is based on direct measurements of the silicon open-circuit potential shift generated by the interaction between metallic ions and the silicon-based sensing surface. The new sensor can have practical applications in the on-line monitoring of microelectronic chemical processing. The detection of Ag+ content in KODAK waste water was carried out successfully by this novel sensor. Trace levels of organic impurities in the hydrofluoric acid solutions and in the cleanroom air were characterized by multiple internal reflection infrared spectroscopy (MIRIS) using an organics probe prepared directly from a regular silicon wafer.

Five different complexes of aluminum and amino acids have been synthesized and characterized. Reaction between aluminum halides and amino acids that do not contain either a carboxylate or a hydroxy group in the side chain produce complexes of the general formula, [Al(amino acid)_n(halide)_3-n]_m. The most prevalent form of this form of complex is where n = 2, and an example of this in which the halide is replaced by hydroxide ligand has been structurally characterized. The complex for which n = 3 may be obtained by employing a large excess of acid, and that for which n = 1 may be obtained by employing either equimolar conditions or an excess of aluminum halide. Reactions of aluminum halides with amino acids that contain either a carboxylate or hydroxy-containing side chain may result in complexes in which the side-chain is also bound. These proved impossible to characterize fully in the case of aspartic acid. For serine, however, a complex in which the amino acid binds in a chelating fashion through both the carboxylate and hydroxy groups was isolated. It was possible to form complexes when utilizing aluminum alkyls as the metal source. However, these complexes could only be isolated when the reactivity …

Calixarenes are a class of macrocyclic compounds that have garnered interest in large part because of their ability to form host-guest complexes with various types of molecules. For all of the studies of complex formation by calixarenes, most of the work to date has concentrated upon the smaller calixarenes, and little is understood about the relationship between the complexes formed when in solution and that observed in the solid state. The first part of the study, presented in Chapter 3, is of the solid-state properties of two of the larger calixarenes, and in comparison to other reported structures reveals patterns to the observed conformations both in the solid state and in solution. The formation of metal complexes has also been investigated and has focused extensively upon the metals as guests. Thus, the ability of the calixarenes to act as ligands in inorganic complexes has been virtually untapped, despite the polyoxo binding site they can easily provide, and very few metallocalixarenes have been reported. The second part of this study goes beyond the simple solid-state properties of such compounds, and involves the synthesis of several metallocalixarenes as part of a project directed at the functionalization of calixarenes with the components of …

Part I: In the first study of pyrethroids, twenty-one novel pyrethroid esters bearing strong electron-withdrawing groups (e.g., halomethylketo and nitro groups) in the double bond side chain of the cyclopropane acid moiety have been synthesized and evaluated for insect toxicity. Rather than the usually employed Wittig reaction for these syntheses, the novel pyrethroid acid moieties were prepared by amino acidcatalyzed Knoevenagel condensations under mild conditions. In the second study of pyrethroids, fourteen pyrethroid-like carbonates were synthesized by condensation of a variety of alcohols and the chloroformates of the corresponding known pyrethroid alcohols.

Investigations presented here are (a) the study of reorientational dynamics and internal rotation in transition metal complexes by NMR relaxation experiments, and (b) the study of ligand exchange dynamics in transition metal complexes by exchange NMR experiments. The phenyl ring rotation in Ru3(CO)9(μ3-CO)(μ3-NPh) and Re(Co)2(CO)10(μ3- CPh) was monitored by 13C NMR relaxation experiments to probe intramolecular electronic and/or steric interactions. It was found that the rotation is relatively free in the first complex, but is restrained in the second one. The steric interactions in the complexes were ascertained by the measurement of the closest approach intramolecular distances. The rotational energy barriers in the two complexes were also calculated by using both the Extended Hiickel and Fenske-Hall methods. The study suggests that the barrier is due mainly to the steric interactions. The exchange NMR study revealed two carbonyl exchange processes in both Ru3(CO)9(μ3-CO)(μ3-NPh) and Ru3(CO)8(PPh3)(μ3-CO)(μ3-NPh). The lower energy process is a tripodal rotation of the terminal carbonyls. The higher energy process, resulting in the exchange between the equatorial and bridging carbonyls, but not between the axial and bridging carbonyls, involves the concerted formation of edge-bridging μ2-CO moieties. The effect of the PPh3 ligand on the carbonyl exchange rates has been discussed. …

The fluorescence spectrum of many polycyclic aromatic compounds (PACs) depends upon solvent polarity. The emission spectrum of PAC monomers consists of several major vibronic bands labeled I, II, etc., in progressive order. Emission intensity enhancement of select bands is observed in polar solvents.

Pulsed laser flash photolysis with both visible and infrared detection has been applied to the study of the displacement of weakly coordinating ligands (Lw) by strongly "trapping" nucleophiles (Ls) containing either an olefinic functionality (Ls = 1-hexene, 1-decene, 1-tetradecene) or nitrogen (Ls = acetonitrile, hydrocinnamonitrile) from the photogenerated 16 electron pentacarbonylchromium (0) intermediate. 5-Chloropent-l-ene (Cl-ol), a potentially bidentate ligand, has been shown to form (ol-Cl) pentacarbonylchromium (0), in which Cl-ol is bonded to Cr via a lone pair on the chlorine, and isomerize to (Cl-ol) pentacarbonylchromium (0), in which Cl-ol is bonded to the olefinic functionality on the submillisecond time scale. This process has been studied in both the infrared and visible region employing both fluorobenzene or n-heptane as the "inert" diluent. Parallel studies employing 1-chlorobutane and 1-hexene were also evaluated and showed great similiarity with the Cl-ol system. The data supported a largely dissociative process with a possibility of a small interchange process involving the H's on the alkyl chain. Studies were also carried out for various Cr(CO)6/arene/Ls systems (arene = various alkyl or halogenated substituted benzenes). The data indicated that for both C6H5R (R=various alkyl chains) or multi-alkyl substituted arenes (i.e. o-xylene, 1,2,3-trimethylbenzene) containing an "unhindered" ring-edge, bonding …