In organometallic study, activation of C-F bond is an interesting subject, especially in fluoro-substituted propyl groups, because of their different reactivityn from fluoro-substituted methyl and ethyl groups. In this thesis, fluorinated propyl groups were studied on a Cu(111) surface under ultrahigh vacuum (UHV) conditions. We have examined the kinetics of the £]-elimination reaction in CF3CF2CH2-Cu, CHF2CF2CH2-Cu, and CF3CH2CH2-Cu. These species all decompose via £]-elimination to give CF3CF=CH2, CHF2CF=CH2, and CF3CH=CH2. The first two species undergo £]-fluoride elimination and the third one undergoes £]-hydride elimination. The difference in activation energies between the first two accounts for the charge separation (R-C£]+£_¡KF−£_¡KM+£_) in the transition state proposed by Gellman. The activation energies for £]-hydride elimination (CF3CH2CH2-Cu) and £]-fluoride elimination (CF3CF2CH2-Cu) was also compared. The activation energy for £]-fluoride elimination is found to be lower than that of £]-hydride elimination. In the studies of reaction pathways for perfluoropropyl groups (n-C3F7-Cu and i-C3F7-Cu) on Cu(111), we discovered novel chemistry in TPD. n-C3F7-Cu undergoes Cu-C homolytic cleavage (radical desorption) at 340 K, whereas i-C3F7-Cu eliminates the £]-fluorine at 365 K. By changing the Cu-C bond length in the i-C3F7-5Cu models their IR spectra was calculated. We discover that the IR of i-C3F7-5Cu with shorter Cu-C bond (1.728Å) is more similar to the experimental IR spectra. That demonstrates the bond strength of Cu-C bond of i-C3F7-Cu is too strong to undergo Cu-C homolytic cleavage at 340 K. Hence, £]-F decomposition becomes the favorite pathway to i-C3F7-Cu because there are more £]-F atoms available in this moiety.

Abstract Thirty phosphane ligands were prepared and characterized. Aryl groups of the phosphane ligands were modified through change in functionality. The side chains were the following: trifluoromethylphenyl, selenomethylphenyl, 9-anthryl, alkyl-substituted aryl groups, and pyridyl and alkyl groups. In addition, three chromium carbonyl complexes of potentially bidentate arylphosphanes containing nitrogen heteroatoms were prepared and characterized. Characterization of the isolated complexes verified the monodentate coordination from phosphorus and two bidentate coordination modes, (P,N)-bound and (N,N')-bound. Ligands and complexes were characterized by 1H, 13C{1H}, 31P{1H}, and two-dimensional NMR spectroscopy, X-ray crystallography, and mass spectrometry. The 13C{1H} and 31P{1H} NMR spectra, and calculated cone angles of the o-alkyl-substituted aryl- and arylalkylphosphane ligands provided valuable parameters, which could be plotted against catalytic results in the search for correlations between the structures and catalytic behavior of ligands. Correlations were found between the parameters and the catalytic behavior of Rh-catalysts modified with the o-alkyl-substituted phenylphosphanes. The research reported here was directed toward the preparation and characterization of phosphane ligands which would favor the formation of isobutanal in propene hydroformylation. The o-alkyl-substituted arylphosphanes, which were studied most throughly, gave the highest selectivity to isobutanal but at the cost of activity. Linear n-butanal was still the main product, though only barely. Alkyl substituents in meta position increased the activity of propene hydroformylation even up to the level with the reference ligand PPh3, but, the selectivity decreased simultaneously.

The reaction of 2-[(diphenylphosphino)methyl]-6-methylpyridine (PN) with Os3(CO)12-n(MeCN)n [where n = 0 (1), 1 (2), 2 (3)] has been investigated. Os3(CO)12 reacts with PN in the presence of Me3NO to afford the clusters Os3(CO)11(1-PN) (4) and 1,2-Os3(CO)10(1-PN)2 (5). X-ray diffraction analyses confirm the equatorial coordination of the phosphine(s) in 4 and 5, with the two phosphines in the latter cluster exhibiting a 1,2-trans orientation about the Os-Os vector that contains the two ligands. Treatment of the MeCN-substituted cluster Os3(CO)11(MeCN) and PN (1:1 ratio) in CH2Cl2 gives clusters 4 and 5, in addition to HOs3(η1-Cl)(CO)10(1-PN) (6) as a result of competitive activation of the reaction solvent. Cluster 6 contains 48e- and the diffraction structure reveals the presence of axial chloride and equatorial phosphine ligands which are located on adjacent osmium atoms. The bridging hydride ligand in 6 spans the Cl,P-substituted Os-Os vector. The reaction of Os3(CO)10(MeCN)2 with PN furnishes 5, 6, and 1,1-Os3(CO)10(2-PN) (7) in yields that are dependent on the reagent stoichiometry and reaction solvent. The solid-state structure of 7 confirms the chelation of the PN ligand to a single osmium atom via the pyridine and phosphine moieties at axial and equatorial sites, respectively. The bonding in 7 relative to other possible stereoisomers has been explored by DFT calculations, and the diffraction structure is computed as the thermodynamically most stable form of this cluster. Cluster 4 is photosensitive and CO loss gives 7, in addition to the formation of the dihydride H2Os3(CO)8[µ-CH(NC5H3)CH2PPh2] (8), whose origin derives from the double metalation of the C-6 methyl group of the PN ligand in 7. Photolysis of 7 yields 8 without detectable observation of the expected intermediate hydride HOs3(CO)9[µ-CH2(NC5H3)CH2PPh2]. The PN ligand in 7 undergoes P-C bond activation in toluene at 110 °C to afford the 50e cluster Os3(CO)9(µ-C6H4)(µ-PPh), which contains face-capping benzyne and phosphinidene moieties. The bonding between the benzyne moiety and the opened Os3 frame in 9 has been examined computationally, and these data are discussed relative to and π bonding contributions from the metalated aryl ring to the cluster polyhedron. Thermolysis of BrRe(CO)5 with 4-(2,2-dimethylhydrazino)dimethylhydrazone-3(Z)-penten-2-one in toluene at 70 °C furnishes the new β-diketimine-substituted complex fac-BrRe(CO)3[(Me2NNCMe)2CH2] (1) in 50-70 isolated yield. Product 1 is also obtained in comparable yield when the same reactants are irradiated at 366 nm at room temperature in fluid solution. Treatment of the parent ligand with the "lightly stabilized" rhenium compound fac-BrRe(CO)3(THF)2 affords 1 as the sole observable rhenium product. Complex 1 has been characterized in solution by IR and 1H NMR spectroscopy, and the molecular structure has been determined by single-crystal X-ray diffraction analysis.

The initial purpose of this study was to determine if steric problems would account for the difference in the products obtained in the reaction of the N-(substituted)phthalimide with low and high molecular weight amines.

Zeolites are crystalline aluminosilicates that are frequently used as catalysts to transform chemical feedstocks into more useful materials in a size- or shape-selective fashion; they are one of the earliest forms of nanotechnology. Zeolites can also be used, especially in the form of zeolite membranes (layers of zeolite on a support), to separate mixtures based on the size of the molecules. Recent advances have also created the possibility of using zeolites as alkaline catalysts, in addition to their traditional applications as acid catalysts and catalytic supports. Transport and catalysis in zeolites are greatly affected by physical and chemical defects. Such defects can be undesirable (in the case of zeolite membranes), or desirable (in the case of nitrogen-doped alkaline zeolites). Studying zeolites at the relevant length scales requires indirect experimental methods such as vapor adsorption or atomic-scale modeling such as electronic structure calculations. This dissertation explores both experimental and theoretical characterization of zeolites and zeolite membranes. Physical defects, important in membrane permeation, are studied using physical adsorption experiments and models of membrane transport. The results indicate that zeolite membranes can be modeled as a zeolite powder on top of a support—a “supported powder,” so to speak—for the purposes of adsorption. Mesoporosity that might be expected based on permeation and confocal microscopy measurements is not observed. Chemical defects—substitutions of nitrogen for oxygen—are studied using quantum mechanical models that predict spectroscopic properties. These models provide a method for simulating the 29Si NMR spectra of nitrogendefected zeolites. They also demonstrate that nitrogen substitutes into the zeolite framework (not just on the surface) under the proper reaction conditions. The results of these studies will be valuable to experimentalists and theorists alike in our efforts to understand the versatile and complicated materials that are zeolites.

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