Quinoxaline-functionalized, cage-annulated oxa- and thiacrown ethers have been synthesized as possible specific metal host systems. The synthesis and characterization of quinoxaline-functionalized, cage-annulated oxa- and thiacrown ethers have been described. The characterization of these host systems have been fully achieved in solution by using various techniques such as IR, 1H NMR, and 13C NMR spectroscopic methods, high-resolution mass spectrometry (HRMS), elemental microanalysis, and X-ray crystallographic analysis in case of one quinoxaline-functionalized, cage-annulated oxacrown ether compound. The synthesis of the diphosphine ligand 2,3-bis(diphenylphosphino)-N-p-tolylmaleimide (bmi) is described. The substitution of the MeCN ligands in the activated cluster 1,2-Os3(CO)10(MeCN)2 by the diphosphine ligand bmi proceeds rapidly at room temperature to furnish a mixture of bridging and chelating Os3(CO)10(bmi) isomers and the ortho-metalated product HOs3(CO)9[μ-(PPh2)C=C{PPh(C6H4)}C(O)N(tolyl-p)C(O)]. Thermolysis of the bridging isomer 1,2-Os3(CO)10(bmi) under mild conditions gives the chelating isomer 1,1-Os3(CO)10(bmi), whose molecular structure has been determined by X-ray crystallography. The kinetics for the ligand isomerization have been investigated by UV-vis and 1H NMR spectroscopy in toluene solution over the temperature range of 318-348 K. On the basis of kinetic data conducted in the presence of added CO and the Eyring activation parameters, a non-dissociative phosphine migration across one of the Os-Os bonds is proposed. Orthometalation of …

The dissertation consists of the following three sections: 1. Hydroxyapatite (HA) coatings. In this work, we deposited HA precursor films from weak basic electrolytic solution (pH= 8-9) via an electrochemical approach; the deposits were changed into crystallite coatings of hydroxyapatite by sintering at specific temperatures (600-800 ºC). The formed coatings were mainly characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). XRD patterns show well-defined peaks of HA when sintered under vacuum conditions. FTIR measurements indicate the existence of hydroxyl groups, which were confirmed by the characteristic intensity of the stretching and bending bands at ~3575 and ~630 cm-1, respectively. The SEM shows an adhesive, crack free morphology for the double-layer coating surface of the samples sintered in a vacuum furnace. 2. Silver/polymer/clay nanocomposites. Silver nanoparticles were prepared in layered clay mineral (montmorillonite)/polymer (PVP: poly (vinyl pyrrolidone)) suspension by an electrochemical approach. The silver particles formed in the bulk suspension were stabilized by the PVP and partially exfoliated clay platelets, which acted as protective colloids to prevent coagulation of silver nanoparticles together. The synthesized silver nanoparticles/montmorillonite/PVP composite was characterized and identified by XRD, SEM, and TEM (transmission electron microscopy) measurements. 3. Ce-doped lead …

Employing correlation consistent basis sets coupled with electronic structure methods has enabled accurate predictions of chemical properties for second- and third-row main group and transition metal molecular species. For third-row (Ga-Kr) molecules, the performance of the correlation consistent basis sets (cc-pVnZ, n=D, T, Q, 5) for computing energetic (e.g., atomization energies, ionization energies, electron and proton affinities) and structural properties using the ab initio coupled cluster method including single, double, and quasiperturbative triple excitations [CCSD(T)] and the B3LYP density functional method was examined. The impact of relativistic corrections on these molecular properties was determined utilizing the Douglas-Kroll (cc-pVnZ-DK) and pseudopotential (cc-pVnZ-PP) forms of the correlation consistent basis sets. This work was extended to the characterization of molecular properties of novel chemically bonded krypton species, including HKrCl, FKrCF3, FKrSiF3, FKrGeF3, FKrCCF, and FKrCCKrF, and provided the first evidence of krypton bonding to germanium and the first di-krypton system. For second-row (Al-Ar) species, the construction of the core-valence correlation consistent basis sets, cc-pCVnZ was reexamined, and a revised series, cc-pCV(n+d)Z, was developed as a complement to the augmented tight-d valence series, cc-pV(n+d)Z. Benchmark calculations were performed to show the utility of these new sets for second-row species. Finally, the correlation consistent basis …

In this research the validity of various computational techniques has been determined and applied the appropriate techniques to investigate and propose a good catalytic system for C-H bond activation and functionalization. Methane being least reactive and major component of natural gas, its activation and conversion to functionalized products is of great scientific and economic interest in pure and applied chemistry. Thus C-H activation followed by C-C/C-X functionalization became crux of the synthesis. DFT (density functional theory) methods are well suited to determine the thermodynamic as well as kinetic factors of a reaction. The obtained results are helpful to industrial catalysis and experimental chemistry with additional information: since C-X (X = halogens) bond cleavage is important in many metal catalyzed organic syntheses, the results obtained in this research helps in determining the selectivity (kinetic or thermodynamic) advantage. When C-P bond activation is considered, results from chapter 3 indicated that C-X activation barrier is lower than C-H activation barrier. The results obtained from DFT calculations not only gave a good support to the experimental results and verified the experimentally demonstrated Ni-atom transfer mechanism from Ni=E (E = CH2, NH, PH) activating complex to ethylene to form three-membered ring products but also validated …

This study is based on survey responses of 224 general chemistry instructors at United States (U.S.) community colleges and universities representing 46 states. The mean values of General Chemistry Topic Coverage (GCTC) score, developed by this researcher specifically for this dissertation study as a measure of course content, were statistically analyzed. The aim of this study is to answer five research questions: (a) Is there a difference in mean GCTC scores between U.S. community colleges and four-year colleges and universities? (b) If there is a difference in mean GCTC score between the two study groups, what are the observed differences in subtopics covered between community colleges and four-year colleges and universities? (c) Considering both community colleges and universities, is there a difference in mean GCTC score between the different designated U.S. regions? (d) Considering both community college and university professors, is there a difference in GCTC score for professors with a master's degree compared to those with a doctorate?, and (e) Is there a correlation between GCTC score and the percentage of students that major in science? Results indicate that there is a statistically significant difference in course content between community colleges and universities, there is a statistically significant difference …

The tetraruthenium cluster H4Ru4(CO)12 has been studied for its reactivity with the unsaturated diphosphine ligands (Z)-Ph2PCH=CHPPh2, 4,5-bis (diphenylphosphino)-4-cyclopenten-1,3-dione, bis(diphenyphosphino)benzene and 1,8- bis(diphenyl phosphino)naphthalene under thermal, near-UV photolysis, and Me3NO-assisted activation. All three cluster activation methods promote loss of CO and furnish the anticipated substitution products that possess a chelating diphosphine ligand. Clusters 1, 2, 3 and 4 have been characterized in solution by IR and NMR spectroscopies, and these data are discussed with respect to the crystallographically determined structures for all new cluster compounds. The 31P NMR spectral data and the solid-state structures confirm the presence of a chelating diphosphine ligand in all four new clusters. Sealed NMR tubes containing clusters 1, 2, 3 and 4 were found to be exceeding stable towards near-UV light and temperatures up to ca. 100°C. The surprisingly robust behavior of the new clusters is contrasted with the related cluster Ru3(CO)10(bpcd) that undergoes fragmentation to the donor-acceptor compound Ru2(CO)6(bpcd) and the phosphido-bridged compound Ru2(CO)6 (µ-PPh2)[µ-C=C(PPh2)C(O)CH2C(O)] under mild conditions. The electrochemical properties have been investigated in the case of clusters 1 and 2 by cyclic voltammetry, and the findings are discussed with respect to the reported electrochemical data on the parent cluster H4Ru4(CO)12.