The microwave spectrum and conformations of halomethyl oxiranes: Bromomethyl oxirane

The microwave spectrum of bromomethyl oxirane

has been recorded in the range 12.5–18 and 26.5–40 GHz. Lines of the two bromine isotopic species of three rotamers, gauche-1 (Br near the O atom), gauche-2 (Br near the CH₂ of the ring) and cis have been identified. The gauche-1 lines are strongest, and the cis lines the weakest. The rotational constants (in MHz) are: gauche-1 (⁷⁹Br) A = 12 296.050, B = 1 391.677, C = 1 317.360, (⁸¹Br) A = 12 199.162, B = 1 378.321, C = 1 309.142; gauche-2 (⁷⁹Br) A = 12 278.436, B = 1 378.830, C = 1 304.852, (⁸¹Br) A = 12 189.869, B = 1 369.696, C = 1 301.584; cis (⁷⁹Br) A = 7 733.314, B = 1 808.087, C = 1 737.340, (⁸¹Br) A = 7 726.16, B = 1 801.159, C = 1 730.125.     

The microwave spectra,conformations, and dipole moments of 4-cyanocyclopentene

Microwave spectra have been observed and assigned for the axial and equatorial conformations of 4-cyanocyclopentene. For the axial species the rotational constants in megahertz are A = 5095.77, B = 2185.81, and C = 1936.50; for the equatorial species the values are A = 6762.66, B = 1916.72, and C = 1590.60. Dipole moment measurements yielded |μ_a| = 3.48 D and |μ_c| = 2.51 D for the axial form and |μ_a| = 3.85 D and |μ_c| = 1.10 D for the equatorial form. Relative intensity measurements showed the equatorial conformer to be 400 ± 60 cal mole^?1 lower in energy. Several sets of vibrational satellites were observed and natural abundance C¹³ spectra were obtained for the equatorial conformer.     

The microwave spectrum and structure of chloromethyl cyclopropane

The microwave spectra of $\text{CH}{}_2\text{CH}{}_2\text{CH}$CH₂³⁵Cl and $\text{CH}{}_2\text{CH}{}_2\text{CH}$CH₂³⁷Cl have been observed and lines assigned to the gauche form. The rotational constants in MHz and distortion constants in KHz are: C₃H₅CH₂³⁵Cl, A = 11745.65, B = 2047.274, C = 1886.622, Δ_J = 0.85, Δ_JK = ? 0.9, Δ_K = 44., δ_J = ? 0.099, δ_K = 19.1, C₃H₅CH₂³⁷Cl, A = 11691.61B = 1997.664, C = 1842.823, Δ_J = 0.7, Δ_JK = ? 64.6, Δ_K = 2400, δ_J = 0.19, δ_K = ? 67.     

The microwave spectra and structures of epihalohydrins: Epichlorohydrin

The microwave spectrum of the two chlorine isotopic species of epichlorohydrin ($\text{CH}{}_2\text{OCH}$CH₂Cl) is reported. The structure is a gauche conformation with the Cl atom twisted toward the oxygen side of the ring. The observed rotational constants (in MHz) and centrifugal distortion constants (in kHz) are: C₂H₃OCH₂³⁵Cl; A = 13 373.02, B = 2080.353, C = 1932.469, Δ_JK = ? 6, Δ_K = 2400, δ_J = ? 0.43, δ_K = 17, H_KJ = ? 0.13, H_K = 570, h_JK = 0.061, h_K = ? 5.1: C₂H₃OCH₂³⁷Cl; A = 13 361.24, B = 2028.853, C = 1887.990, Δ_JK = 0.31, Δ_K = 1669., δ_J = ? 0.16, δ_K = 54.1.     

Vibrational spectra and conformations of selenanisole

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 52, No. 1, pp. 56–60, January, 1990.     

IR spectra of chloromethyl derivatives of dioxans and dioxolans

A cyclic structure is demonstrated for the chloroacetals produced from chloroacetaldehyde and polyhydric alcohols. The stretching frequency of the chloromethyl group is not affected by the dioxan and dioxolan rings, or by the number of chlorine atoms in the molecule.     

The microwave and millimeter-wave spectra of hypochlorous acid

To permit atmospheric monitoring of the molecule, the microwave spectra of two isotopic species of hypochlorous acid, HOCl, have been measured in the frequency range 8–650 GHz. Three b-type branches and an a-type Q branch have all been measured for the first time; improved measurements have been made for the a-type R branches. The analysis has included combination differences of earlier high-resolution infrared spectra to give accurate values for all rotational constants, five quartic and five higher degree centrifugal distortion constants, as well as the chlorine nuclear quadrupole and spin-rotation coupling constants. From the Stark effect, accurate values have also been obtained for both components of the molecular dipole moment. A table of transition frequencies of potential use in atmospheric monitoring is presented.     

Vibrational spectra and conformations of ethyl phenyl sulfide

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 55, No. 4, pp. 541–546, October, 1991.     

The microwave spectra and dipole moments of the cyanopyridines

Rotational transitions of 4-cyanopyridine, 3-cyanopyridine and 2-cyanopyridine have been observed and assigned. The values of the rotational constants for these three molecules are (in MHz):

$\text{4-cyanopyridine}\text{A=6000.}\text{B=1541.19}\text{C=1226.00}\text{3-cyanopyridine}\text{A=5823.01}\text{B=1571.34}\text{=1237.17}\text{2-cyanopyridine}\text{A=5835.756}\text{1598.219}\text{1254.460}$

The dipole moment components were also measured and are (in Debye):

$\text{4-cyanopyridine}\text{μ}{}_{\mathrm{a}}\text{=1.96}\text{μ}{}_{\mathrm{b}}\text{=0}\text{μ}{}_{\mathrm{total}}\text{=1.96}\text{3-cyanopyridine}\text{μ}{}_{\mathrm{a}}\text{=3.13}\text{μ}{}_{\mathrm{b}}\text{=1.90}\text{μ}{}_{\mathrm{total}}\text{=3.66}\text{2-cyanopyridine}\text{μ}{}_{\mathrm{a}}\text{=5.47}\text{μ}{}_{\mathrm{b}}\text{=1.87}\text{μ}{}_{\mathrm{total}}\text{=5.78}$

     

The microwave spectra of PH2D and PHD2, and the harmonic force field and structure of phosphine

Measurements of the pure rotational spectra of PH₂D and PHD₂ have been extended to include new Q-branch transitions and R-branch transitions. The rotational constants have been independently evaluated for the first time, along with some quartic and sextic centrifugal distortion constants. The spectrum of PD₃ has been reanalyzed to make the constants consistent with those reported for PH₃. The new results have been incorporated in a harmonic force field analysis. Both ground state average (r₂) and equilibrium (r_e) structures have been estimated.     

The microwave spectra of deuterated silanes,germanes, and stannanes

A previous measurement of the rotational spectra of SiH₃D, SiH₂D₂, and SiHD₃ has been extended in frequency region to determine rotational constants and quartic centrifugal distortion constants. Similar observations have been performed on GeH₃D, GeH₂D₂, and GeHD₃, consisting of five, three, and three Ge isotopes, respectively, and also on SnH₃D, SnH₂D₂, and SnHD₃ with seven, three, and three Sn isotopes, respectively. The observed rotational constants were analyzed to estimate the equilibrium internuclear distance for the three molecules.