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  • Articles: DFG German National Licenses  (33)
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  • Articles: DFG German National Licenses  (33)
Material
Years
  • 1
    Electronic Resource
    Electronic Resource
    Measurements of Microwave Rotational Transitions for Cyclopentadienyltungsten Dicarbonyl Nitrosyl (1995)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 11820-11822 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100031a005
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  • 2
    Electronic Resource
    Electronic Resource
    Microwave measurements of rhenium quadrupole coupling in cyclopentadienyl rhenium tricarbonyl (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 108 (1998), S. 8878-8883 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Microwave measurements of rotational transitions for cyclopentadienyl rhenium tricarbonyl were performed in the gas phase using pulsed beam Fourier transform microwave spectroscopy. One hundred and sixty five transitions were assigned to two isotopomers of rhenium. The location of the rhenium atom near the center of mass produced significant overlap between the spectra of the two isotopomers. The data were accurately fit using a symmetric top, rigid rotor Hamiltonian that included nuclear quadrupole coupling and centrifugal distortion constants. The rotational constants obtained were B(187Re) = 724.9794(2), B(185Re) = 724.9795(2). The quadrupole coupling constants obtained were eQq(187Re) = 614.464(12) and eQq(185Re) = 649.273(14) MHz. The successful fitting of the measured spectra to a symmetric top Hamiltonian indicates that the cyclopentadienyl group retains C5v symmetry, and the Re(CO)3 group C3v symmetry in the gas phase. The measured rotational constants are in reasonable agreement with those calculated from the structural parameters obtained in the earlier x-ray work. The Re quadrupole coupling constants obtained are compared with values for other complexes. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.476334
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  • 3
    Electronic Resource
    Electronic Resource
    Determination of structural parameters for the half-sandwich compounds cyclopentadienyl thallium and cyclopentadienyl indium and indium quadrupole coupling for cyclopentadienyl indium using microwave spectroscopy (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 3766-3773 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Microwave rotational transitions for J′←J=2←1 and 3←2 were measured in the 7–11 GHz range for three isotopomers of (C5H5)In. Similar transitions (up to J′←J=5←4) for eight isotopomers of (C5H5)Tl were measured in the 5–15 GHz range. The rotational constants of the most abundant isotopomers are B(Cp 203Tl)=1467.9730(11) MHz, B(Cp 205Tl) =1465.0723(14) MHz, B(Cp 113In)=1809.9785(30) MHz, and B(Cp 115In)=1800.8199(18) MHz (Cp=C5H5). The quadrupole coupling strengths for the indium compounds are eQq(Cp 113In)=−118.397(69) MHz and eQq(Cp 115In)=−119.981(31) MHz. Spectra for single-substitution 13C isotopomers were seen in natural abundance. Deuterated samples of CpTl were prepared to obtain spectra for deuterium-substituted isotopomers. Analysis of the spectra allowed the determination of the following structural parameters; for (C5H5)Tl, r(Tl–C5)=2.413(3) Å, r(C–C)=1.421(10) Å, r(C–H)=1.082(9) Å and (angle)C5–H=0.9(2)° (C5 represents the planar, 5-carbon ring of C5H5), and for (C5H5)In, r(In–C5)=2.314(4) Å and r(C–C)=1.426(6) Å. A Kraitchman analysis was performed on the available isotopomers for comparison of r0 and rs values. Both structural analyses indicate that the hydrogen atoms in (C5H5)Tl are bent slightly out of the carbon plane away from the coordinated metal atom. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.474734
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  • 4
    Electronic Resource
    Electronic Resource
    Measurements of the structure of methyltrioxorhenium using microwave spectroscopy (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 2187-2192 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The rotational spectra for six isotopomers of methyltrioxorhenium (MTO) were measured in the 6–14 GHz range using a Flygare–Balle-type pulsed-beam microwave spectrometer. The measured transition frequencies were analyzed to obtain rotational constants and quadrupole coupling strengths. Rotational constants from the new measurements were used, along with previous results for the normal and 13C isotopomers, to determine the complete, three-dimensional structure for MTO. The bond lengths obtained are r(Re–C)=2.074(4) Å, r(Re–O)=1.703(2) Å, and r(C–H)=1.088(7) Å. The interbond angles are (angle)Re–C–H=108.9(2)° and (angle)C–Re–O=106.4(4)°. This complex appears to have C3v symmetry in the gas phase, unlike the solid-state structure. Structural parameters are compared with neutron-diffraction, electron-diffraction, and density functional theory results. Spectra for the asymmetric-top isotopomers were much more difficult to analyze due to effects of off-diagonal quadrupole coupling terms and possible internal rotation. The Re quadrupole coupling strength is increased by 1.4% for CD3ReO3 compared with CH3ReO3, illustrating a secondary isotope effect. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.474618
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  • 5
    Electronic Resource
    Electronic Resource
    Microwave spectra and structure of HI–HF complexes (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 1083-1089 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Microwave spectra for the HI–HF, HI–DF, DI–HF, and DI–DF complexes were measured using a pulsed-beam, Fourier-transform microwave spectrometer. Rotational transitional transitions were measured over the 4–18 GHz range to an accuracy of 5 kHz. The spectroscopic constants obtained by fitting the observed transitions for the series HI–HF, HI–DF, DI–HF, and DI–DF are, respectively: (B+C)/2=2220.7482(8), 2173.236(2), 2209.623(4), and 2162.884(6) MHz; eQq(I)=687.01(2), 693.63(5), 725.96(4), and 727.8(1) MHz; ΔeQq(I)=−42(2), −50(6), −210(14), and −141(25) kHz; DJ =8.86(3), 8.25(6), 8.1(6), and 8.6(5) kHz. This complex has an interesting triangular structure with the H–I and H–F bonds making an acute angle of 70.1 (2.8)°. The iodine atom is coaxial with HF with a heavy atom separation R0(I–F)=3.660(8) A(ring). Hyperfine structure due to deuterium quadrupole coupling and H–F spin–spin interactions was resolved and measured.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.452248
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  • 6
    Electronic Resource
    Electronic Resource
    Microwave measurements and ab initio dynamics of the large amplitude ring puckering motion in 2-sulpholene (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 7305-7313 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Microwave measurements were made on the rotational spectrum of 2-sulpholene using a modified Flygare–Balle pulsed beam Fourier transform spectrometer. Analysis and calculations provided information on the large amplitude ring puckering vibration of this system. Twelve and six rotational transitions were measured for the v=0 and v=1 states of the ring puckering vibration, respectively. The transitions for each vibrational state were fitted to a Watson's A reduced Hamiltonian including terms for quartic distortion yielding for v=0 the values B=2125.96(6), C=1983.28(8), ΔJK=0.664(4), ΔK=−0.34(4) MHz, and for v=1 the values A=3995(26), B=2128.3(1), C=1984.6(1), ΔJK=−0.8(1), ΔK=−32(6) MHz. Subsequently, ab initio calculations were performed at the self-consistent-field (SCF)/3-21G*, MP2/6-31G*, and MP4/6-31G* levels of theory to determine the barrier to inversion. The MP4/6-31G* barrier was ΔE=116 cm−1, and can be considered to be the most accurate barrier value calculated in this study. An ab initio potential energy curve was calculated at the SCF/3-21G* level in terms of a single parameter (ω) describing the large amplitude motion of the ring puckering. Vibration-coordinate dependence of the effective reduced mass associated with this large amplitude motion and the resultant kinetic energy expression was determined. The solutions of a one-dimensional Schrödinger equation solved within this double well potential yield a separation between the v=0 and v=1 large amplitude motion vibrational states of 8 cm−1 when the effective reduced mass was assumed constant, and a separation of 9 cm−1 when the effective reduced mass was expressed as a function of the ω coordinate. The v=0 and v=1 eigenfunctions for the SCF ring puckering potential were found to give vibrationally averaged rotational constants in good agreement with those obtained from the microwave spectrum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.465712
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  • 7
    Electronic Resource
    Electronic Resource
    Microwave measurements of manganese quadrupole coupling in cyclopentadienyl manganese tricarbonyl (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 2449-2452 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Microwave measurements of rotational transitions in cyclopentadienyl manganese tricarbonyl were made using a Flygare–Balle type pulsed beam Fourier transform microwave spectrometer operating in the 4–14 GHz range. Ninety-six hyperfine transitions were assigned for this prolate symmetric top for the rotational transitions J=2→3, 3→4, 4→5, 5→6, and 6→7. Molecular constants obtained from the analysis of the spectrum are B=828.0333(6) MHz, DJ=0.088(9) kHz, DJK=−0.04(3) kHz, eQqaa(Mn)=68.00(4) MHz, Cbb(Mn)=−5.5(8) kHz. The distortion parameter DJ for CpMn(CO)3 is compared to other DJ values for similar type transition metal complexes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.462048
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  • 8
    Electronic Resource
    Electronic Resource
    Microwave spectra and structures of the NNO–HCN, 15NNO–HCN, and NNO–DCN complexes (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 3881-3886 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A total of 60 a- and b-dipole rotational transitions were measured in the 4–18 GHz range for the NNO–HCN, 15NNO–HCN, and NNO–DCN bimolecular complexes using a pulsed-beam, Fourier transform microwave spectrometer. Spectroscopic constants (A−DK), B, C, DJ, DJK, eQqaa (N of HCN), and eQqbb (N of HCN) were obtained by fitting the observed transition frequencies with a first-order quadrupole coupling interaction Hamiltonian. The structure of the complex appears to be planar with NNO and NCH nearly parallel. It can be described with the distance Rcm between the center-of-masses of the monomer subunits, the angle θ between HCN and Rcm, and the angle φ between N2O and Rcm. A least-squares fit to the nine rotational constants to obtain the structure parameters Rcm, θ, and φ, produced three local minimia for bent structures with standard deviations of 〈25 MHz. A Kraitchman analysis was used to determine magnitudes of principal axes coordinates for the N of HCN, and the terminal N of NNO. The best nonlinear least-squares fit result (structure I, lowest standard deviation of the fit =7.2 MHz) produced the best match to the coordinates from the Kraitchman analysis. The spectroscopic constants B, C, and eQqaa were used in a second structural analysis to determine values for Rcm, θ, and φ. These results were compared with the above coordinates. The best least-squares fit structure parameters for the vibrationally averaged structure are Rcm =3.253(4) A(ring), θ=89.1(5.4)°, and φ =76.4(0.4)°. Comparisons are made with other similar weakly bound complexes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459690
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  • 9
    Electronic Resource
    Electronic Resource
    Erratum: The rotational spectra and centrifugal distortion parameters for the NNO–DF and ONN–DF complexes [J. Chem. Phys. 90, 3458 (1989)] (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 1487-1488 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459727
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  • 10
    Electronic Resource
    Electronic Resource
    The rotational and tunneling spectrum of the H2S⋅CO2 van der Waals complex (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 6408-6419 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The rotational spectra of H2S⋅CO2 and two deuterated forms have been observed using a pulsed-beam Fourier-transform microwave spectrometer. For each of the three complexes we assign a-type and c-type transitions which are split into a "weak'' and a "strong'' intensity component. The analysis based on that previously used for the (H2O)2 complex and modified for application to H2S⋅CO2, allowed us to assign internal rotation, inversion tunneling states of the H2S and CO2 units in the complex. The following rotational constants were determined for the ground tunneling state of each species: for H2S⋅CO2, A=11 048.0(26) MHz, B=2147.786(4) MHz, and C=1806.468(4) MHz; for HDS⋅CO2, A=10 769(35) MHz, B=2107.26(24) MHz, and C=1775.83(24) MHz; and for D2S⋅CO2, A=10 356.2(28) MHz, B=2065.376(8) MHz, and C=1746.122(8) MHz. The electric dipole moments were determined for the H2S⋅CO2 and D2S⋅CO2 species, resulting in the values μa=0.410(14) D and μc=0.822(10) D for the H2S⋅CO2 species. The structure of the complex has the CO2 and the S atom of H2S in a T-shaped configuration. The H2S plane is nearly orthogonal to the CO2–S plane with an angle of about 92° and the H2S⋅CO2 center-of-mass separation Rc.m. is 3.498(3) A(ring).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458320
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