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Timothy S. Zwier - One of the best experts on this subject based on the ideXlab platform.
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strong field coherence breaking as a tool for identifying methyl rotor states in Microwave Spectra 2 hexanone
Journal of Chemical Physics, 2019Co-Authors: Sean M Fritz, Piyush Mishra, Timothy S. ZwierAbstract:The rotational spectrum of 2-hexanone was recorded over the 8–18 GHz region using a chirped pulse Fourier transform Microwave spectrometer. Strong field coherence breaking (SFCB) was utilized to selectively modulate the intensities of rotational transitions belonging to the two lowest energy conformers of 2-hexanone, aiding the assignment. In addition, the SFCB method was applied for the first time to selectively identify rotational transitions built off the two lowest energy hindered methyl rotor states of each conformer, 0a1 and 1e. Since these two states have rotational energy levels with different nuclear spin symmetries, their intensities could be selectively modulated by the resonant monochromatic pulses used in the SFCB method. The difference Spectra, final fit, and structural parameters are discussed for the three assigned conformers of 2-hexanone.The rotational spectrum of 2-hexanone was recorded over the 8–18 GHz region using a chirped pulse Fourier transform Microwave spectrometer. Strong field coherence breaking (SFCB) was utilized to selectively modulate the intensities of rotational transitions belonging to the two lowest energy conformers of 2-hexanone, aiding the assignment. In addition, the SFCB method was applied for the first time to selectively identify rotational transitions built off the two lowest energy hindered methyl rotor states of each conformer, 0a1 and 1e. Since these two states have rotational energy levels with different nuclear spin symmetries, their intensities could be selectively modulated by the resonant monochromatic pulses used in the SFCB method. The difference Spectra, final fit, and structural parameters are discussed for the three assigned conformers of 2-hexanone.
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strong field coherence breaking as a tool for identifying methyl rotor states in Microwave Spectra 2 hexanone
Journal of Chemical Physics, 2019Co-Authors: Sean M Fritz, Piyush Mishra, Timothy S. ZwierAbstract:The rotational spectrum of 2-hexanone was recorded over the 8-18 GHz region using a chirped pulse Fourier transform Microwave spectrometer. Strong field coherence breaking (SFCB) was utilized to selectively modulate the intensities of rotational transitions belonging to the two lowest energy conformers of 2-hexanone, aiding the assignment. In addition, the SFCB method was applied for the first time to selectively identify rotational transitions built off the two lowest energy hindered methyl rotor states of each conformer, 0a1 and 1e. Since these two states have rotational energy levels with different nuclear spin symmetries, their intensities could be selectively modulated by the resonant monochromatic pulses used in the SFCB method. The difference Spectra, final fit, and structural parameters are discussed for the three assigned conformers of 2-hexanone.
Stephen G Kukolich - One of the best experts on this subject based on the ideXlab platform.
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Microwave Spectra and theoretical calculations for two structural isomers of methylmanganese pentacarbonyl
Inorganic Chemistry, 2020Co-Authors: Chakree Tanjaroon, Zunwu Zhou, David Mills, Kristen Keck, Stephen G KukolichAbstract:The first Microwave rotational Spectra for two structural isomers of methylmanganese pentacarbonyl were measured in the 4–9 GHz range using a pulsed-beam Fourier transform Microwave spectrometer. T...
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synthesis Microwave Spectra x ray structure and high level theoretical calculations for formamidinium formate
Journal of Chemical Physics, 2019Co-Authors: Zunwu Zhou, Adam M Daly, Alan R Aitken, Charlotte Cardinaud, Alexandra M Z Slawin, Honghao Wang, Michael H Palmer, Stephen G KukolichAbstract:An efficient synthesis of formamidinium formate is described. The experimental x-ray structure shows both internal and external H-bonding to surrounding molecules. However, in the gas phase, this compound occurs as a doubly hydrogen bonded dimer between formamidine and formic acid. This doubly hydrogen-bonded structure is quite different from the solid state structure. Microwave Spectra were measured in the 6-14 GHz range using a pulsed-beam Fourier transform Microwave (MW) spectrometer. The two nonequivalent N-atoms exhibit distinct quadrupole coupling. The rotational, centrifugal distortion, and quadrupole coupling constants determined from the Spectra have the following values: A = 5880.05(2), B = 2148.7710(2), C = 1575.23473(13), 1.5 χaa (N1) = 1.715(3), 0.5(χbb-χcc) (N1) = -1.333(4), 1.5 χaa (N2) = 0.381(2), 0.25(χbb-χcc) (N2) = -0.0324(2), and DJ = 0.002145(5) MHz. The experimental inertial defect, Δ = -0.243 amu A2, is consistent with a planar structure. Accurate and precise rotational constants (A, B, and C), obtained from the MW measurements, were closely reproduced, within 1%-2% of the measured values, with the M11 DFT theoretical calculations. Detailed comparison of the measured and calculated A, B, and C rotational constants confirms the planar doubly hydrogen bonded structure. The calculated nitrogen quadrupole coupling strengths of the monomer are quite different from either of the two nitrogen sites of the dimer. The poor agreement between measured and calculated quadrupole coupling strengths shows that the dimer is not locked in the equilibrium structure but is likely undergoing large amplitude vibrational motion of the hydrogen atoms moving between the N and O atoms involved in the hydrogen bonding.
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Microwave Spectra structure and the aromatic character of 1 chloroborepin
Journal of Physical Chemistry A, 2018Co-Authors: Aaron M Pejlovas, Zunwu Zhou, Arthur J Ashe, Stephen G KukolichAbstract:High resolution Microwave Spectra for the somewhat unstable compound 1-chloroborepin were measured in the 5–10 GHz range using a pulsed beam Fourier transform Microwave spectrometer. Transitions were assigned and measured for three isotopologues, which include the most abundant isotopologue, 11B35Cl, and the less abundant 10B35Cl and 11B37Cl isotopologues. The molecular parameters (MHz) determined for the 11B35Cl isotopologue are A = 3490.905(35), B = 1159.38520(79), C = 870.59492(56), 1.5χaa (11B) = −0.220(22), 0.25(χbb – χcc) (11B) = −1.5300(99), 1.5χaa (35Cl) = −54.572(33), and 0.25(χbb – χcc) (35Cl) = 4.7740(79). The inertial defect is calculated to be Δ = −0.174 amu A2 from the experimental rotational constants, indicating a planar structure with some out of plane vibrational motion. An extended Townes–Dailey analysis was performed on the 11B and 35Cl nuclei to determine the electron occupations in the valence hybridized orbitals using the experimental quadrupole coupling strengths. From the analysis...
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Microwave Spectra molecular structure and aromatic character of 4a 8a azaboranaphthalene
Journal of Chemical Physics, 2016Co-Authors: Aaron M Pejlovas, Adam M Daly, Arthur J Ashe, Stephen G KukolichAbstract:The Microwave Spectra for seven unique isotopologues of 4a,8a-azaboranaphthalene [hereafter referred to as BN-naphthalene] were measured using a pulsed-beam Fourier transform Microwave spectrometer. Spectra were obtained for the normal isotopologues with (10)B, (11)B, and all unique single (13)C and the (15)N isotopologue (with (11)B), in natural abundance. The rotational, centrifugal distortion and quadrupole coupling constants determined for the (11)B(14)N isotopologue are A = 3042.712 75(43) MHz, B = 1202.706 57(35) MHz, C = 862.220 13(35) MHz, DJ = 0.06(1) kHz, 1.5χaa ((14)N) = 2.5781(61) MHz, 0.25(χbb - χcc) ((14)N) = - 0.1185(17) MHz, 1.5χaa (11B) = - 3.9221(75) MHz, and 0.25(χbb - χcc) ((11)B) = - 0.9069(24) MHz. The experimental inertial defect is Δ = - 0.159 amu A(2), which is consistent with a planar structure for the molecule. The B-N bond length from the experimentally determined structure is 1.47 A, which indicates π-bonding character between the B and N. The measured quadrupole coupling strengths provide important and useful information about the bonding, orbital occupancy, and aromatic character for this aromatic molecule. Extended Townes-Dailey analyses were used to determine the B and N electron sp(2)-hybridized and p-orbital occupations. These results are compared with electron orbital occupations from the natural bond orbital option in theoretical calculations. From the analyses, it was determined that BN-naphthalene has aromatic character similar to that of other N-containing aromatics. The results are compared with similar results for B-N bonding in 1,2-dihydro-1,2-azaborine and BN-cyclohexene. Accurate and precise structural parameters were obtained from the Microwave measurements on seven isotopologues and from high-level G09 calculations.
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Microwave Spectra and structure of the cyclopropanecarboxylic acid formic acid dimer
Journal of Chemical Physics, 2015Co-Authors: Aaron M Pejlovas, Stephen G KukolichAbstract:The rotational spectrum of the cyclopropanecarboxylic acid–formic acid doubly hydrogen bonded dimer has been measured in the 4-11 GHz region using a Flygare-Balle type pulsed-beam Fourier transform Microwave spectrometer. Rotational transitions were measured for the parent, four unique singly substituted 13C isotopologues, and a singly deuterated isotopologue. Splittings due to a possible concerted double proton tunneling motion were not observed. Rotational constants (A, B, and C) and centrifugal distortion constants (DJ and DJK) were determined from the measured transitions for the dimer. The values of the rotational (in MHz) and centrifugal distortion constants (in kHz) for the parent isotopologue are A = 4045.4193(16), B = 740.583 80(14), C = 658.567 60(23), DJ = 0.0499(16), and DJK = 0.108(14). A partial gas phase structure of the dimer was derived from the rotational constants of the measured isotopologues, previous structural work on each monomer units and results of the calculations.
Michael C. L. Gerry - One of the best experts on this subject based on the ideXlab platform.
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Microwave Spectra and structures of krauf kragf and kragbr 83kr nuclear quadrupole coupling and the nature of noble gas noble metal halide bonding
Journal of the American Chemical Society, 2004Co-Authors: Jason M Thomas, Nicholas R Walker, S A Cooke, Michael C. L. GerryAbstract: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 Br2) contained in the backing gas of the jet (usually Ar). Rotational constants; geometries; centrifugal distortion constants; vibration frequencies; and 197Au, 79Br, and 81Br nuclear quadrupole coupling constants have all been evaluated. The complexes are unusually rigid and have short Kr−Au and Kr−Ag bonds. The 197Au nuclear quadrupole coupling constant differs radically from its value in an AuF monomer. In addition 83Kr 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 83Kr nuclear quadrupole coupling constants have been found for both complexes. Both the 197Au and 83Kr hyperfine...
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Microwave Spectra geometries and hyperfine constants of ocagx x f cl br
Inorganic Chemistry, 2001Co-Authors: Nicholas R Walker, Michael C. L. GerryAbstract:A pulsed jet cavity Fourier transform Microwave spectrometer has been used to measure the rotational Spectra of OCCuX (X ) F, Cl, Br) in the frequency range 5-21 GHz. Metal atoms were generated via laser ablation and were allowed to react with CO and a halide precursor, prior to stabilization of the products within a supersonic jet. These are the first experimental observations of OCCuF and OCCuBr and the first high-resolution spectroscopic study of gas-phase OCCuCl. All three molecules were found to be linear. Rotational constants, centrifugal distortion constants, nuclear quadrupole coupling constants, and nuclear spin-rotation coupling constants have been precisely determined. The rotational constants have been used to evaluate the various bond lengths, and the results are in good agreement with the trend established for OCAuX species. The C-O distance is found to be comparatively short and close to that of free CO. The M-C distance is longer than that predicted by ab initio calculations, and the Cu-X distances are very similar to those observed in the corresponding metal halides. Vibrational wavenumbers have been estimated from the distortion constants and are compared with the results of various ab initio studies. Changes in the Cu, Cl, and Br nuclear quadrupole coupling constants indicate that substantial charge rearrangement takes place on coordination with CO, consistent with the formation of strong Cu-C bonds. Mulliken orbital population analyses have been performed and provide evidence of ﷿-back-donation from Cu in all of the species studied. The evaluated nuclear spin-rotation coupling constants have been used to estimate the 63 Cu nuclear shielding constants, U, and their spans (? )i n OC 63 CuF, OC 63 Cu 35 Cl, and OC 63 Cu 79 Br.
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the Microwave Spectra and structures of ar agx x f cl br
Journal of Chemical Physics, 2000Co-Authors: Corey J Evans, Michael C. L. GerryAbstract:The rotational Spectra of the complexes Ar–AgF, Ar–AgCl, and Ar–AgBr have been observed in the frequency range 6–20 GHz using a pulsed jet cavity Fourier transform Microwave spectrometer. All the complexes are linear and rather rigid in the ground vibrational state, with the Ar–Ag stretching frequency estimated as ∼140 cm−1. Isotopic data have been used to calculate an r0 structure for Ar–AgF, while for Ar–AgCl and Ar–AgBr partial substitution structures have also been obtained. To reduce zero-point vibrational effects a double substitution method (rd) was employed to calculate the structures of Ar–AgCl and Ar–AgBr. The Ar–Ag bond distance has been found to be rather short and to range from 2.56 A in Ar–AgF to 2.64 A in Ar–AgBr. Ab initio MP2 and density functional theory calculations for Ar–AgF and Ar–AgCl model the geometries and stretching frequency well, and predict an Ar–Ag bond energy in Ar–AgF of ∼23 kJ mol−1. These results indicate that the Ar–AgX complexes are more strongly bound than typical van der Waals complexes. Analysis of the halogen nuclear quadrupole coupling constants was unable to confirm whether extensive electron rearrangement occurs upon formation of the complexes.
Sean M Fritz - One of the best experts on this subject based on the ideXlab platform.
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strong field coherence breaking as a tool for identifying methyl rotor states in Microwave Spectra 2 hexanone
Journal of Chemical Physics, 2019Co-Authors: Sean M Fritz, Piyush Mishra, Timothy S. ZwierAbstract:The rotational spectrum of 2-hexanone was recorded over the 8–18 GHz region using a chirped pulse Fourier transform Microwave spectrometer. Strong field coherence breaking (SFCB) was utilized to selectively modulate the intensities of rotational transitions belonging to the two lowest energy conformers of 2-hexanone, aiding the assignment. In addition, the SFCB method was applied for the first time to selectively identify rotational transitions built off the two lowest energy hindered methyl rotor states of each conformer, 0a1 and 1e. Since these two states have rotational energy levels with different nuclear spin symmetries, their intensities could be selectively modulated by the resonant monochromatic pulses used in the SFCB method. The difference Spectra, final fit, and structural parameters are discussed for the three assigned conformers of 2-hexanone.The rotational spectrum of 2-hexanone was recorded over the 8–18 GHz region using a chirped pulse Fourier transform Microwave spectrometer. Strong field coherence breaking (SFCB) was utilized to selectively modulate the intensities of rotational transitions belonging to the two lowest energy conformers of 2-hexanone, aiding the assignment. In addition, the SFCB method was applied for the first time to selectively identify rotational transitions built off the two lowest energy hindered methyl rotor states of each conformer, 0a1 and 1e. Since these two states have rotational energy levels with different nuclear spin symmetries, their intensities could be selectively modulated by the resonant monochromatic pulses used in the SFCB method. The difference Spectra, final fit, and structural parameters are discussed for the three assigned conformers of 2-hexanone.
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strong field coherence breaking as a tool for identifying methyl rotor states in Microwave Spectra 2 hexanone
Journal of Chemical Physics, 2019Co-Authors: Sean M Fritz, Piyush Mishra, Timothy S. ZwierAbstract:The rotational spectrum of 2-hexanone was recorded over the 8-18 GHz region using a chirped pulse Fourier transform Microwave spectrometer. Strong field coherence breaking (SFCB) was utilized to selectively modulate the intensities of rotational transitions belonging to the two lowest energy conformers of 2-hexanone, aiding the assignment. In addition, the SFCB method was applied for the first time to selectively identify rotational transitions built off the two lowest energy hindered methyl rotor states of each conformer, 0a1 and 1e. Since these two states have rotational energy levels with different nuclear spin symmetries, their intensities could be selectively modulated by the resonant monochromatic pulses used in the SFCB method. The difference Spectra, final fit, and structural parameters are discussed for the three assigned conformers of 2-hexanone.
Michael J Tubergen - One of the best experts on this subject based on the ideXlab platform.
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rotational Spectra and conformational structures of 1 phenyl 2 propanol methamphetamine and 1 phenyl 2 propanone
Journal of Physical Chemistry A, 2006Co-Authors: Michael J Tubergen, David F. Plusquellic, R J Lavrich, R D SuenramAbstract:Microwave Spectra have been recorded for 1-phenyl-2-propanol, methamphetamine, and 1-phenyl-2-propanone from 11 to 24 GHz using a Fourier-transform Microwave spectrometer. Only one spectrum from a ...
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effect of solvent on molecular conformation Microwave Spectra and structures of 2 aminoethanol van der waals complexes
Journal of Chemical Physics, 2003Co-Authors: Michael J Tubergen, Charles R Torok, R J LavrichAbstract:Rotational Spectra of the 13C isotopomers of the 2-aminoethanol monomer have been recorded in natural abundance using a Fourier-transform Microwave spectrometer. The two sets of 13C isotopomer rotational constants were used to complete the 2-aminoethanol substitution structure. Rotational Spectra of the van der Waals complexes 2-aminoethanol–water and 2-aminoethanol–argon were also recorded. Sixteen a-, b-, and c-type transitions were fit to the Watson A-reduction Hamiltonian for 2-aminoethanol–argon yielding A=4986.762(2) MHz, B=1330.693(3) MHz, and C=1143.933(3) MHz. Fifteen a- and b-type transitions for 2-aminoethanol–water were fit to A=4886.451(5) MHz, B=3356.038(2) MHz, and C=2311.715(2) MHz. The Spectra are assigned to the lowest-energy ab initio [MP2/6-311++G(d,p)] structures of the two complexes. The conformation of 2-aminoethanol is unchanged in the argon complex, and the argon is 3.775 A from the monomer center of mass. A network of intermolecular hydrogen bonds in the 2-aminoethanol–water comp...