Determination of Molecular Structures from Ground State Rotational Constants

1958 ◽  
Vol 29 (4) ◽  
pp. 864-874 ◽  
Author(s):  
C. C. Costain
Keyword(s):  
Ground State ◽  
Molecular Structures ◽  
Rotational Constants

Determination of the ground state rotational constants for formaldehyde: H212CO and H213CO

1979 ◽  
Vol 74 (2) ◽  
pp. 327-329 ◽  
Author(s):  
G. Winnewisser ◽  
R.A. Cornet ◽  
F.W. Birss ◽  
R.M. Gordon ◽  
D.A. Ramsay ◽  
...  
Keyword(s):  
Ground State ◽  
Rotational Constants

Axis Switching in the Transition of HCO: Determination of Molecular Geometry

1975 ◽  
Vol 53 (19) ◽  
pp. 2232-2241 ◽  
Author(s):  
J. M. Brown ◽  
D. A. Ramsay
Keyword(s):  
Ground State ◽  
Molecular Geometry ◽  
Spin Rotation ◽  
Resolving Power ◽  
Rotational Constants ◽  
Reliable Determination ◽  
Axis Switching ◽  
Rotation Constant ◽  
Ground State Geometry

The [Formula: see text] band systems of HCO and DCO have been reinvestigated with higher resolving power than in earlier work. Some weak lines have been assigned to K′ = 0 – K″ = 0 and K′ = 0 – K″ = 2 subbands; these lines derive their intensity from axis switching. The new data give values for the A rotational constants of HCO and DCO and permit a more reliable determination of the ground state geometry, viz, r0(CH) = 1.125(5) Å, r0(CO) = 1.175(1) Å, [Formula: see text]. The sign of the spin–rotation constant εaa has been shown to be positive.

The 4550 Å band system of glyoxal. IV. Vibration–rotational analyses for 11 bands of 13C2H2O2 and determination of molecular geometries

1977 ◽  
Vol 55 (5) ◽  
pp. 390-395 ◽  
Author(s):  
F. W. Birss ◽  
D. B. Braund ◽  
A. R. H. Cole ◽  
R. Engleman Jr. ◽  
A. A. Green ◽  
...  
Keyword(s):  
Excited State ◽  
Electron Diffraction ◽  
Excellent Agreement ◽  
Ground State ◽  
Band System ◽  
Vibrational Frequencies ◽  
Geometrical Parameters ◽  
Rotational Constants ◽  
Vibrational Constants

Rotational analyses have been carried out for 11 bands of the [Formula: see text](π*–n) system of 13C2H2O2 in absorption. Approximately 12 000 lines have been assigned, and rotational and vibrational constants have been evaluated. The following vibrational frequencies have been determined: ν2′ = 1365.17 cm−1, ν4′ = 918.81 cm−1, ν5′ = 502.48 cm−1, ν7′ = 229.40 cm−1, ν7″ = 124.61 cm−1Using the rotational constants for C2H2O2, C2HDO2, C2D2O2, 13C2H2O2, and C2H218O2, the following geometrical parameters have been evaluated: in the Ã1Au excited state, r0(CH) = 1.115 ± 0.010 Å, r0(CO) = 1.252 ± 0.016 Å, r0(CC) = 1.460 ± 0.025 Å, [Formula: see text], [Formula: see text]; in the [Formula: see text] ground state, r0(CH) = 1.109 ± 0.008 Å, r0(CO) = 1.202 ± 0.012 Å, r0(CC) = 1.527 ± 0.017 Å, [Formula: see text], [Formula: see text]. The ground state parameters are in excellent agreement with earlier electron diffraction results.

scholarly journals Rotational Spectrum of Methylcyanoacetylene A New Millimeter Wave Spectrometer

1983 ◽  
Vol 38 (1) ◽  
pp. 64-67 ◽  
Author(s):  
M. Bester ◽  
M. Tanimoto ◽  
B. Vowinkel ◽  
G. Winnewisser ◽  
Koichi Yamada
Keyword(s):  
Millimeter Wave ◽  
Ground State ◽  
Wave Spectra ◽  
Rotational Spectrum ◽  
Rotational Constants ◽  
Reflex Klystron ◽  
Wave Spectrometer

Abstract The ground state rotational spectrum of methylcyanoacetylene, CH3CCCN, has been observed between 8 and 90 GHz, yielding precise rotational constants and a determination of the nuclear hyperfine costant eqQ = -4.0 ± 0.2 MHz. The millimeter wave spectra (70 - 90 GHz) were obtained with a newly constructed spectrometer, employing a synthesizer - controlled reflex klystron as source.

The ν4 Vibration–Rotation Bands of C6H6 and C6D6: The Analysis of the Bands and the Determination of the Bond Lengths

1974 ◽  
Vol 52 (20) ◽  
pp. 1949-1955 ◽  
Author(s):  
A. Cabana ◽  
J. Bachand ◽  
J. Giguère
Keyword(s):  
High Resolution ◽  
Ground State ◽  
Spectroscopic Constants ◽  
Vibrational States ◽  
Rotational Constants ◽  
Bond Lengths ◽  
Vibration Rotation

The ν4. vibration–rotation bands of benzene and benzene-d6 have been recorded with high resolution. The K = 0 subbands have been analyzed and spectroscopic constants for both vibrational states have been calculated. Assuming D6h symmetry for the molecules the bond lengths have been determined from the ground state rotational constants of the two isotopic molecules. The values obtained are: r0(C—C) = 139.64 ± 0.02 pm and r0(C—H) = 108.31 ± 0.13 pm.

ROTATIONAL ANALYSIS OF THE β BANDS OF PHOSPHORUS MONOXIDE

1959 ◽  
Vol 37 (2) ◽  
pp. 136-143 ◽  
Author(s):  
Nand Lal Singh
Keyword(s):  
Ground State ◽  
Band System ◽  
Electronic States ◽  
Rotational Analysis ◽  
Rotational Constants ◽  
Fine Structures ◽  
Π State

The fine structures of three of the β bands of PO which occur near 3200 Å have been analyzed. The analysis shows that the upper state of this band system is a 2Σ and not a 2Π state as previously believed. The rotational constants of both electronic states have been determined and it is found that the ground state constants, previously determined from the γ bands, are incorrect.

Crystal structure determination of the conformation of two bicyclo[3.3.1]nonan-ones

1985 ◽  
Vol 63 (6) ◽  
pp. 1166-1169 ◽  
Author(s):  
John F. Richardson ◽  
Ted S. Sorensen
Keyword(s):  
Crystal Structure ◽  
Direct Methods ◽  
Chair Conformation ◽  
Molecular Structures ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Final Agreement

The molecular structures of exo-7-methylbicyclo[3.3.1]nonan-3-one, 3, and the endo-7-methyl isomer, 4, have been determined using X-ray-diffraction techniques. Compound 3 crystallizes in the space group [Formula: see text] with a = 15.115(1), c = 7.677(2) Å, and Z = 8 while 4 crystallizes in the space group P21 with a = 6.446(1), b = 7.831(1), c = 8.414(2) Å, β = 94.42(2)°, and Z = 2. The structures were solved by direct methods and refined to final agreement factors of R = 0.041 and R = 0.034 for 3 and 4 respectively. Compound 3 exists in a chair–chair conformation and there is no significant flattening of the chair rings. However, in 4, the non-ketone ring is forced into a boat conformation. These results are significant in interpreting what conformations may be present in the related sp2-hybridized carbocations.

scholarly journals The Microwave Spectrum of 3,4-Dihydro-1,2-Pyran

1985 ◽  
Vol 40 (9) ◽  
pp. 913-919
Author(s):  
Juan Carlos López ◽  
José L. Alonso
Keyword(s):  
Dipole Moment ◽  
Excited States ◽  
Ground State ◽  
Principal Axis ◽  
Microwave Spectrum ◽  
Average Intensity ◽  
Ring Conformation ◽  
Vibrationally Excited ◽  
Rotational Constants ◽  
Displacement Measurements

Abstract The rotational transitions of 3,4-dihydro-1,2-pyran in the ground state and six vibrationally excited states have been assigned. The rotational constants for the ground state (A = 5198.1847(24), B = 4747.8716(24) and C = 2710.9161(24) have been derived by fitting μa, μb and μc-type transitions. The dipole moment was determined from Stark displacement measurements to be 1.400(8) D with its principal axis components |μa| =1.240(2), |μb| = 0.588(10) and |μc| = 0.278(8) D. A model calculation to reproduce the ground state rotational constants indicates that the data are consistent with a twisted ring conformation. The average intensity ratio gives vibrational separations between the ground and excited states of the ring-bending and ring-twisting modes of ~ 178 and ~ 277 cm-1 respectively.

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