@article {1008, title = {Microwave spectra and structures of KrAuF, KrAgF, and KrAgBr; Kr-83 nuclear quadrupole coupling and the nature of noble gas-noble metal halide bonding}, journal = {Journal of the American Chemical Society}, volume = {126}, number = {4}, year = {2004}, note = {ISI Document Delivery No.: 768GATimes Cited: 42Cited Reference Count: 76}, month = {Feb}, pages = {1235-1246}, type = {Article}, abstract = {Microwave spectra of the complexes KrAuF and KrAgBr have been measured for the first time using a cavity pulsed jet Fourier transform microwave spectrometer. The samples were prepared by laser ablation of the metal from its solid and allowing the resulting plasma to react with an appropriate precursor (Kr, plus SF6 or Br-2) contained in the backing gas of the jet (usually At). Rotational constants; geometries; centrifugal distortion constants; vibration frequencies; and Au-197, Br-79, and Br-81 nuclear quadrupole coupling constants have all been evaluated. The complexes are unusually rigid and have short Kr-Au and Kr-Ag bonds. The Au-197 nuclear quadrupole coupling constant differs radically from its value in an AuF monomer. In addition Kr-83 hyperfine structure has been measured for KrAuF and the previously reported complex KrAgF. The geometry of the latter has been reevaluated. Large values for the Kr-83 nuclear quadrupole coupling constants have been found for both complexes. Both the Au-197 and Kr-83 hyperfine constants indicate a large reorganization of the electron distribution on complex formation. A thorough assessment of the nature of the noble gas-noble metal bonding in these and related complexes (NgMX; Ng is a noble gas, M is a noble metal, and X is a halogen) has been carried out. The bond lengths are compared with sums of standard atomic and ionic radii. Ab initio calculations have produced dissociation energies along with Mulliken populations and other data on the electron distributions in the complexes. The origins of the rigidity, dissociation energies, and nuclear quadrupole coupling constants are considered. It is concluded that there is strong evidence for weak noble gas-noble metal chemical bonding in the complexes.}, keywords = {CHEMICAL-BONDS, DIPOLE MOMENT, ELECTRIC-RESONANCE METHOD, GROUND-STATE, HYPERFINE CONSTANTS, MILLIMETER-WAVE, MOLECULAR-CONSTANTS, PURE ROTATIONAL, SPECTRA, SUBMILLIMETER-WAVE SPECTRA, VANDERWAALS COMPLEX}, isbn = {0002-7863}, url = {://000188534200055}, author = {Thomas, J. M. and Walker, N. R. and Cooke, S. A. and Gerry, M. C. L.} } @article {4371, title = {The forbidden rotational Q-branch of CH3CF3: Torsional properties and (A(1)-A(2)) splittings}, journal = {Journal of Molecular Spectroscopy}, volume = {190}, number = {2}, year = {1998}, note = {ISI Document Delivery No.: 103JBTimes Cited: 8Cited Reference Count: 29}, month = {Aug}, pages = {324-340}, type = {Article}, abstract = {The pure rotational spectrum driven by the small distortion dipole moment perpendicular to the symmetry axis has been investigated between 8 and 18 GHz for CH3CF3 in the ground vibrational state using a pulsed Fourier transform waveguide spectrometer. This molecule has been selected as a prototype for the case of a symmetric top with small (similar to 500 kHz) torsional energy splittings in the ground torsional state (v(6) = 0). In this state, six (k +/- 3 <{\textendash} k) e-branch series have been measured for lower state K = \k\ between 3 and 8 with 27 less than or equal to J less than or equal to 75, For (v(6) = 1), three series with lower state K between 5 and 7 with 49 less than or equal to J less than or equal to 66 have been observed. In two of these series, the torsional fine structure extending over similar to 6.8 MHz has been fully resolved. The (A(1) - A(2)) splitting has been measured in the (v(6) = 0) series (K = 6 <{\textendash} 3) for 37 less than or equal to J less than or equal to 74. The global data set of 443 frequencies included avoided-crossing molecular-beam splittings of Meerts and Ozier (1991. Chem. Phys. 152, 241-259) and mm-wave R-branch measurements of Bocquet et nl. (1994. J, Mol. Spectrosc. 165, 494-499). In a weighted least-squares analysis, a good fit was obtained by varying 18 parameters in a Hamiltonian that represented both the torsional effects and the sextic splittings. Effective values have been determined for both rotational constants, eight torsional parameters including the barrier height, six diagonal centrifugal distortion constants, and two centrifugal distortion constants (epsilon and epsilon(J)) that characterize the (Delta k = +/-3) matrix elements. The difficulties are discussed that arise in defining a unique model for the torsional terms in the Hamiltonian when a high barrier symmetric top is investigated by distortion moment spectroscopy. The redundancies are investigated that exist in the quartic and sextic Hamiltonian for a near-spherical top such as CH3CF3. (C) 1998 Academic Press.}, keywords = {CH3SIH3, CROSSING MOLECULAR-BEAM, INTERNAL-ROTATION, METHYL SILANE, MICROWAVE FOURIER-TRANSFORM, MILLIMETER-WAVE, POLYATOMIC-MOLECULES, SPECTROSCOPY, SPECTRUM, SYMMETRIC, TOPS}, isbn = {0022-2852}, url = {://000075153100016}, author = {Ozier, I. and Schroderus, J. and Wang, S. X. and McRae, G. A. and Gerry, M. C. L. and Vogelsanger, B. and Bauder, A.} } @article {3914, title = {Microwave spectrum and geometry of cyanogen N-oxide, NCCNO}, journal = {Journal of Molecular Spectroscopy}, volume = {181}, number = {2}, year = {1997}, note = {ISI Document Delivery No.: WH318Times Cited: 22Cited Reference Count: 32}, month = {Feb}, pages = {316-322}, type = {Article}, abstract = {The microwave spectrum of cyanogen N-oxide, NCCNO, has been investigated in the frequency region between 4 and 23 GHz, using a pulsed jet Fourier transform microwave spectrometer. The spectrum is that of a linear molecule. Transitions of five isotopomers have been analyzed, and r(0), r(s), and r(I,e), geometries have been determined. The geometry and the N-14 nuclear quadrupole coupling constants have been used to compare NCCNO to similar molecules. Though the present data indicate strongly that the molecule is truly linear, they are insufficient to rule out quasi-linear behavior completely. (C) 1997 Academic Press.}, keywords = {CONSTANTS, GROUND-STATE, MILLIMETER-WAVE, MOLECULE, NCNCO, PARAMETERS, ROTATIONAL SPECTRA, SPECTROSCOPY}, isbn = {0022-2852}, url = {://A1997WH31800008}, author = {Brupbacher, T. and Bohn, R. K. and Jager, W. and Gerry, M. C. L. and Pasinszki, T. and Westwood, N. P. C.} } @article {3340, title = {STRUCTURE, HARMONIC FORCE-FIELD AND HYPERFINE COUPLING-CONSTANTS OF NITROSYL CHLORIDE}, journal = {Journal of the Chemical Society-Faraday Transactions}, volume = {91}, number = {19}, year = {1995}, note = {ISI Document Delivery No.: TA547Times Cited: 8Cited Reference Count: 43}, month = {Oct}, pages = {3347-3355}, type = {Article}, abstract = {The pure rotational spectra of five isotopic species of nitrosyl chloride were measured using a cavity pulsed microwave Fourier-transform spectrometer. Some a-type transitions of all five isotopomers, and some weak b-type transitions of four of these isotopomers were measured in the 4-26 GHz frequency range. Precise values for the rotational constants and the quartic centrifugal distortion constants were obtained. The rotational constants were used in structure determinations and the centrifugal distortion constants were used in a refinement of the harmonic general valence force field. A harmonic central valence force field was also calculated. Hyperfine structure in these transitions arising from quadrupole and spin-rotation coupling interactions was also observed. Diagonal and off-diagonal quadrupole coupling constants and diagonal spin-rotation coupling constants of both the chlorine and nitrogen nuclei were determined. The principal quadrupole coupling constants were evaluated and used to calculate the approximate ionic character of the N-Cl bond. The spin-rotational coupling constants were used to calculate the diamagnetic shielding factor for the nitrogen nucleus; the magnitude of this value indicates a fairly ionic N-Cl bond.}, keywords = {CL-35, EQUILIBRIUM STRUCTURE, FLUORIDE, INFRARED-SPECTRA, MILLIMETER-WAVE, MOLECULAR-STRUCTURE, N-14, PARAMETERS, SPECTROSCOPY}, isbn = {0956-5000}, url = {://A1995TA54700004}, author = {Gatehouse, B. and Muller, H. S. P. and Heineking, N. and Gerry, M. C. L.} }