@article {1169, title = {Intermolecular activation of hydrocarbon C-H bonds initiated by the tungsten hydrocarbyl hydrido complexes Cp*W(NO)(R)(H)(PMe3) (R = alkyl, aryl)}, journal = {Organometallics}, volume = {24}, number = {4}, year = {2005}, note = {ISI Document Delivery No.: 896HITimes Cited: 5Cited Reference Count: 32}, month = {Feb}, pages = {638-649}, type = {Article}, abstract = {trans-CP*W(NO)(CH2EMe3)(H)(PMe3) (E = C, Si) complexes can be prepared by the hydrogenation at 1 atm of the appropriate Cp*W(NO)(CH2EMe3)(2) precursor in the presence of a slight excess of PMe3. (Our designation of a particular geometrical isomer as cis or trans in this family of complexes indicates the relative positions of the hydrocarbyl and the hydrido ligands in the base of a four-legged piano-stool molecular structure.) The use of D-2 in place of H-2 during these syntheses affords the corresponding trans-Cp*W(NO)(CH2EMe3)(D)(PMe3) (E = C, Si) complexes. The cis-Cp*W(NO)(CH2EMe3)(H)(PMe3) isomers are obtainable by C-H bond-activation reactions of the trans precursors. Thus, activation of SiMe4 by trans-Cp*W(NO)(CH2CMe3)(H)(PMe3) under ambient conditions produces cis-Cp*W(NO)(CH2SiMe3)(H)(PMe3). Similarly, activations of C6H6 and C6D6 at 20-27 degreesC by the trans-Cp*W(NO)(CH2EMe3)(H)(PMe3) complexes produce cis-Cp*W(NO)(C6H5)(H)(PMe3) and cisCp*W(NO)(C6D5)(D)(PMe3), respectively, and the solid-state molecular structure of the latter complex has been established by a single-crystal X-ray crystallographic analysis. Kinetic, mechanistic, and theoretical investigations of these benzene C-H activation processes are consistent with initial trans to cis isomerization of the reactants followed by intramolecular reductive elimination of EMe4 to form the 16-electron Cp*W(NO)(PMe3) intermediate. Subsequent oxidative addition of the incoming benzene substrate to this coordinatively unsaturated intermediate produces the final cis hydrido phenyl complex. These single C-H activation processes are the requisite first steps in the development of these organometallic complexes as catalysts for the selective functionalization of hydrocarbons. All new complexes have been characterized by conventional spectroscopic methods.}, keywords = {CALCULATIONS, density, EFFECTIVE CORE POTENTIALS, MOLECULAR, MOLYBDENUM, ORGANOMETALLIC NITROSYL CHEMISTRY, REACTIVITY}, isbn = {0276-7333}, url = {://000226924800024}, author = {Lee, K. and Legzdins,Peter and Pamplin, C. B. and Patrick, B. O. and Wada, K.} } @article {949, title = {Electron binding energies of Si 2p and S 2p for Si- and S-containing substances by DFT calculations using the model molecules}, journal = {Polymer Journal}, volume = {36}, number = {8}, year = {2004}, note = {ISI Document Delivery No.: 860UCTimes Cited: 2Cited Reference Count: 39}, pages = {600-606}, type = {Article}, abstract = {Si 2p and S 2p core-electron binding energies (CEBE)s of Si- and S-containing molecules were calculated by deMon DFT program using Slater{\textquoteright}s transition-state (TS) concept. In the previous works, we could not obtain the calculated values to the experimental ones of third periodic 2p CEBEs for the molecules within the range of averaged absolute deviation (AAD) of 1.0eV, although the values were calculated by the unrestricted generalized transition-state (uGTS) method. Here, we were able to get the reasonable Si 2p and S 2p CEBEs of 11, and 12 gas molecules in the AAD of 0.37 and 0.46 eV, respectively from the CEBE calculations by the unrestricted generalized diffuse ionization (uGDI) method with a modification of screening constants for third periodic elements of the 2p core-hole. Furthermore, we estimated WD (work function and the other energies) values of seven Si- and S-containing polymers [(Si(CH3)(2))(n) (PDMS), (Si(CH3)(2)O)(n), (PDMSO), (Si(C6H5)CH3)(n) (PMPS), (Si(C6H5)CH3O)(n) (PPMSO), ((CH2CH2)S)(n) (PETHS), ((CH2(CH2)(4)CH2)SO2). (PHMS), ((C6H4)S)(n) (PPS)] from the differences between calculated CEBE values for the model molecules and experimental ones on the solid polymers.}, keywords = {APPROXIMATION, CALCULATIONS, CORE, core-electron binding energy, DENSITY-FUNCTIONAL THEORY, DFT, EMISSION-SPECTRA, ESCA, FILMS, FLUORESCENCE, ION IRRADIATION, POLYMER CONVERSION, X-ray photoelectron, X-ray photoelectron spectra}, isbn = {0032-3896}, url = {://000224367800004}, author = {Motozaki, W. and Otsuka, T. and Endo, K. and Chong, D. P.} } @article {629, title = {Toward binary nitrosyls: Distinctly bent Fe-N-O linkages in base-stabilized Fe(NO)(3)(+) complexes}, journal = {Journal of the American Chemical Society}, volume = {125}, number = {42}, year = {2003}, note = {ISI Document Delivery No.: 733FYTimes Cited: 15Cited Reference Count: 50}, month = {Oct}, pages = {12935-12944}, type = {Article}, abstract = {Air- and moisture-sensitive Fe(NO)(3)(eta(1)-PF6) (1) may be conveniently prepared by treating Fe(NO)(3)Cl with 1 equiv of [Ag][PF6] in CH2Cl2 or by reacting [NO][PF6] with excess iron filings in MeNO2. Complex 1 is thermally sensitive both as a solid and in solutions, and is best handled below -20 degreesC. To isolate 1 reproducibly from MeNO2 solutions it is necessary to remove all traces of propionitrile, which often occurs as an impurity in MeNO2, because it reacts with Lewis-acidic 1 to form [Fe(NO)(3)(EtCN)][PF6] (2). If trace H2O is present during the synthesis of 1, some of the PF6- is converted to PO2F2-, which is sufficiently Lewis basic that it captures two Fe(NO)(3)(+) fragments and forms [(ON)(3)Fe(mu-PO2F2)Fe(NO)(3)]-[PF6] (3). Finally, Fe(NO)(3)(eta(1)-BF4) (4) can be obtained as a green microcrystalline powder by employing the same synthetic methodologies used to prepare 1. The new complexes 1-4 have been characterized by conventional spectroscopic methods, and the solid-state molecular structures of 2, 3, and 4 and their parent compound, Fe(NO)(3)Cl, have been established by X-ray diffraction methods. The iron centers in the Fe(NO)(3) fragments in all these structures exhibit approximately tetrahedral coordination geometries, and the Fe-N-O linkages are distinctly nonlinear with bond angles in the range of 159 to 169degrees. DFT calculations on Fe(NO)(3)(eta(1)-BF4) (4) confirm that its bent Fe-N-O links have an electronic origin and need not be attributed to other factors, such as packing forces in the crystal. Interestingly, the bending of the NO ligands results in an increase in the energy of the HOMO, relative to the linear case, but at the same time causes a decrease in energy of the HOMO-1 and the HOMO-2 molecular orbitals. This more than compensates for the higher energy of the HOMO, resulting in a lower energy structure.}, keywords = {basis set, CALCULATIONS, COORDINATION, CRYSTAL-STRUCTURE, density, impurities, MOLECULAR, NITROMETHANE, PURIFICATION, REFINEMENT, TETRANITROSYLCHROMIUM CR(NO)4}, isbn = {0002-7863}, url = {://000185990300054}, author = {Hayton, T. W. and McNeil, W. S. and Patrick, B. O. and Legzdins,Peter} } @article {396, title = {Coordination and organometallic chemistry of metal-NO complexes}, journal = {Chemical Reviews}, volume = {102}, number = {4}, year = {2002}, note = {ISI Document Delivery No.: 542CKTimes Cited: 139Cited Reference Count: 1130}, month = {Apr}, pages = {935-991}, type = {Review}, keywords = {CALCULATIONS, DENSITY-FUNCTIONAL, ENANTIOFACE-BINDING, HYDROGEN-BOND ACTIVATION, IRON-NITROSYL COMPLEXES, LIGAND CYANONITROSYL, {(CRNO)5}, isbn = {0009-2665}, url = {://000175025800005}, author = {Hayton, T. W. and Legzdins,Peter and Sharp, W. B.} } @article {4501, title = {Accurate density-functional calculation of core-electron binding energies by a total-energy difference approach}, journal = {Journal of Chemical Physics}, volume = {111}, number = {21}, year = {1999}, note = {ISI Document Delivery No.: 255TCTimes Cited: 34Cited Reference Count: 52}, month = {Dec}, pages = {9485-9492}, type = {Article}, abstract = {A procedure for calculating core-electron binding energies (CEBEs), based on a total-energy difference approach within Kohn-Sham density functional theory, was investigated. Ten functional combinations and several basis sets (including unscaled, scaled, and core-valence correlated functions) were studied using a database of reliable observed CEBEs. The functionals designed by Perdew and Wang (1986 exchange and 1991 correlation) were found to give the best performance with an average absolute deviation from experiment of 0.15 eV. The scaled basis sets did not perform satisfactorily, but it was found that the core-valence correlated cc-pCVTZ basis functions were an excellent alternative to the cc-pV5Z set as they provided equally accurate results and could be applied to larger molecules. (C) 1999 American Institute of Physics. [S0021-9606(99)30742-X].}, keywords = {APPROXIMATION, CALCULATIONS, CORRELATED MOLECULAR, EXCHANGE-ENERGY, GAS, GAUSSIAN-BASIS SETS, METHANE, MODEL MOLECULES, POLYACRYLONITRILE, RAY PHOTOELECTRON-SPECTRA, ZETA BASIS-SET}, isbn = {0021-9606}, url = {://000083685400006}, author = {Cavigliasso, G. and Chong, D. P.} } @article {4391, title = {Valence orbital electron momentum distributions for oxygen: comparison of EMS measurements with theory}, journal = {Chem. Phys.}, volume = {230}, number = {2-3}, year = {1998}, note = {ISI Document Delivery No.: ZR243Times Cited: 19Cited Reference Count: 72}, month = {May}, pages = {153-186}, type = {Article}, abstract = {

The valence shell binding energy spectra and orbital electron momentum profiles of O-2 have been measured by energy dispersive multichannel electron momentum spectroscopy at an impact energy of 1200 eV + binding energy. The effects of electron correlation on the valence binding energy spectrum are investigated using multi-reference singles and doubles configuration interaction calculations. The presently reported experimental momentum profiles of O-2 display considerably improved statistics compared with previously published EMS results. The measured momentum profiles are compared with cross sections calculated using both unrestricted and restricted open shell Hartree-Fock methods with basis sets ranging from minimal to near Hartree-Fock limit in quality. In addition, the effects of correlation and relaxation on the calculated momentum profiles are investigated using multi-reference singles and doubles configuration interaction calculations of the full ion-neutral overlap distributions. Electron correlation effects in the ground state are further examined using several density functional approaches for the momentum profiles. The present EMS measurements and MRSD-CI calculations clearly show that the binding energy peak at similar to 27.3 eV has significant contributions from both (4) Sigma(u)(-) and (2) Sigma(u)(-) processes in contrast to earlier assignments which have attributed this peak to the C-2 Sigma(u)(-) State alone. Similarly, the binding energy peak at 33 eV is shown to be due to (2) Sigma(u)(-) rather than earlier assignments of (2) Pi(u) character. (C) 1998 Elsevier Science B.V. All rights reserved.

}, keywords = {CALCULATIONS, CONFIGURATION-INTERACTION CALCULATIONS, CORRELATED MOLECULAR, CORRELATION ENERGIES, DENSITY-FUNCTIONAL THEORY, DFT calculations, GAUSSIAN-BASIS SETS, HARTREE-FOCK LIMIT, OPEN-SHELL MOLECULES, PHOTOELECTRON-SPECTROSCOPY, PHOTOIONIZATION CROSS-SECTIONS}, isbn = {0301-0104}, url = {://000073954600002}, author = {Rolke, J. and Zheng, Y. and C. E. Brion* and Wang, Y. A. and Davidson, E. R.} } @article {3065, title = {PURE ROTATIONAL SPECTRUM OF, AND POTENTIAL-ENERGY SURFACE FOR, THE AR-N-2 VAN-DER-WAALS COMPLEX}, journal = {Faraday Discussions}, volume = {97}, year = {1994}, note = {ISI Document Delivery No.: QB093Times Cited: 22Cited Reference Count: 84Meeting on Structure and Dynamics of Van der Waal ComplexesAPR 06-08, 1994DURHAM, ENGLAND}, pages = {105-118}, type = {Proceedings Paper}, abstract = {Pure rotational spectra of three isotopomers of the Van der Waals complex Ar-N-2 have been investigated in the frequency range 3.5-20 GHz, using a pulsed molecular beam cavity microwave Fourier-transform spectrometer. Rotational constants and quartic and sextic centrifugal distortion constants have been obtained, along with N hyperfine constants. The spectra of Ar-N-14(2) and Ar-N-15(2) indicate equivalence of the nitrogen nuclei, and thus confirm C-2v symmetry for the complexes. The measured transition frequencies and the derived constants have been used to test the best available literature potential-energy surfaces for the Ar-N-2 interaction. For this purpose rotational transition frequencies and expectation values of other properties were calculated and compared with the corresponding values from the microwave experiments. A refined version of one of the surfaces has been generated by inclusion of the microwave results.}, keywords = {AR, CALCULATIONS, ELASTIC-SCATTERING MEASUREMENTS, FOCK SCF, INFRARED-SPECTRUM, INTER-MOLECULAR FORCES, INTERMOLECULAR FORCES, N2-AR, RANGE DISPERSION COEFFICIENTS, TRANSFORM MICROWAVE SPECTROSCOPY, VANDERWAALS MOLECULES}, isbn = {0301-7249}, url = {://A1994QB09300009}, author = {Jager, W. and Gerry, M. C. L. and Bissonnette, C. and McCourt, F. R. W.} } @article {7172, title = {KINETIC ISOTOPE EFFECTS IN GAS-PHASE MUONIUM REACTIONS}, journal = {Acs Symposium Series}, volume = {502}, year = {1992}, note = {ISI Document Delivery No.: JY550Times Cited: 16Cited Reference Count: 101}, pages = {111-137}, type = {Review}, abstract = {The study of the reaction dynamics of muonium (Mu), an ultralight isotope of hydrogen ((m)Mu/(m)H almost-equal-to 1/9), provides a sensitive measure of mass effects in chemical reactions. The remarkable mass difference between Mu and the other hydrogen isotopes produces large kinetic isotope effects, providing a rigorous test of calculated potential energy surfaces (PES) and reaction rate theories. The low Mu mass also necessitates careful consideration of quantum effects, i.e. tunneling in the reaction coordinate. A review of recent results in gas phase Mu chemistry is presented, including comparison with relevant H chemistry and calculated PESs, where available. The magnitude and direction of the kinetic isotope effect is shown to be a sensitive function of the PES, particularly the height and position of the saddle point.}, keywords = {+ HBR(DBR) ABSTRACTION, ACTION, ADDITION-REACTIONS, CALCULATIONS, CHARGE-EXCHANGE, COLLISIONS, LOW-TEMPERATURES, POTENTIAL-ENERGY SURFACES, PRESSURE-DEPENDENCE, RESONANCE, THERMAL RATE CONSTANTS, TRANSITION-STATE THEORY, TUNNELING PATHS}, isbn = {0097-6156}, url = {://A1992JY55000008}, author = {Baer, S. and Fleming, Donald G. and Arseneau, D. and Senba, M. and Gonzalez, A.} } @article {7248, title = {MUONIUM REACTION-KINETICS WITH THE HYDROGEN HALIDE GASES}, journal = {Journal of Chemical Physics}, volume = {97}, number = {9}, year = {1992}, note = {ISI Document Delivery No.: JX295Times Cited: 14Cited Reference Count: 80}, month = {Nov}, pages = {6309-6321}, type = {Article}, abstract = {The reaction rates of the muonium (Mu) atom with HBr and HI in approximately 1 atm N2 moderator have been measured over the temperature range 160-490 K using the muSR technique. While both abstraction and exchange reactions are possible, only the abstraction reaction should be observable, being moderately exothermic. Comparisons with the corresponding H(D) reactions reveal small kinetic isotope effects in both reactions, which do not vary strongly with temperature (k(Mu)/k(H) almost-equal-to 3.5 near 300 K), consistent with the (classical) ratio of mean velocities. Surprisingly, quantum tunneling, normally facile for similarly exothermic reactions of the ultralight Mu atom (m(Mu)/M(H) almost-equal-to 1/9), appears to be of little importance here. This despite the fact that the (temperature-independent) experimental activation energies are much less than the expected vibrationally adiabatic barrier heights (estimated to be almost-equal-to 1. 5 kcal mol-1) and, particularly in the case of Mu + HI, much less than the corresponding H-atom activation energy: 0. 13 +/- 0.03 vs 0.70 +/- 0. 3 kcal mol-1. In the case of reactions with HBr, the experimental Mu- and H-atom activation energies are much more similar: 0. 51 +/- 0.03 and 0.74 +/- 0. 12 kcal mol-1, respectively, over comparable temperature ranges. These data pose a conundrum in which several compensating effects related to the much lighter Mu-atom mass seem to be involved. Theoretical calculations are urgently required. In our view the topography of the potential-energy surface(s) for H-2X is poorly known, particularly in the region of the barrier. It may be that the abstraction barriers for both Mu + HI and Mu + HBr are considerably later and even smaller than current calculations indicate, resulting in a cancellation of the effects of zero-point-energy shifts and quantum tunneling at the transition state. Differences in skewing angles between Mu and H + HX could favor a shorter tunneling path for the H-atom reaction, possibly compensating for its heavier mass. Steric or rebound effects from "bottlenecks" on the (mass-weighted) potential surfaces for Mu reactivity may also play some role. An upper limit for the 300 K reaction rate of Mu + HCI is given as well. In contrast to both HBr and HI, this reaction is quite endothermic and hence exhibits an inverse kinetic isotope effect (k(Mu) much less than k(H)).}, keywords = {ABSTRACTION REACTIONS, CALCULATIONS, CHEMICAL-REACTIONS, EV COLLISION ENERGY, EXCHANGE-REACTIONS, H+HX COLLISIONS, ISOTOPIC, POTENTIAL-ENERGY SURFACE, QUANTUM-MECHANICAL, RATE CONSTANTS, TRANSITION-STATE THEORY, VARIANTS}, isbn = {0021-9606}, url = {://A1992JX29500038}, author = {Gonzalez, A. C. and Tempelmann, A. and Arseneau, D. J. and Fleming, Donald G. and Senba, M. and Kempton, J. R. and Pan, J. J.} }