The microwave spectrum and structure of trifluoro-ethylene

The microwave spectrum of trifluoroethylene F₂C=CHF is reported, and a number of ground state and vibrationally excited state lines are assigned. The ground state rotational constants are: 10665.31, 3872.36, 2837.97 MHz. The dipole components are μ_a = 0.075 D, μ_b = 1.30 D, and μ_total = 1.30 D. Calculations of the inertia defect of the ground and excited states indicate that the equilibrium configuration is planar.     

The microwave spectrum and structure of trimethylamine-monofluoroborane

The microwave spectra of the ¹¹B¹⁴N, ¹¹B¹⁵N, ¹⁰B¹⁴N and ¹⁰B¹⁵N species of trimethyl-amine-monofluoroborane have been assigned in order to evaluate the B—N distance. Analysis of the rotational constants using either the single or double substitution methods did not give highly precise results. However, by assuming parameters for the amine moiety found in other complexes and fitting the moments of inertia a value of 1.63 ± 0.01 Å was estimated. The method of predicate observables, an alternative fitting process, resulted in d(BN) = 1.633 ± 0.006 Å along with estimates for the other structural parameters.     

The microwave spectrum and electronic structure of cyanogen azide

The rotational spectrum of cyanogen azide has been assigned and yields values of A = 38.06737 GHz, B = 3.18517 GHz and C = 2.93357 GHz. The measured dipole moment components of μ_a = 2.96 D, μ_b = 0.44 D. μ_total = 2.99 D are compared with those computed using a CNDO/2 approach for NCN₃ and several related molecules.     

Radical polymerization of allyl alcohol and allyl acetate

Monoallyl compounds are not readily homopolymerized by a conventional free‐radical mechanism. However, the polymerization of allylbiguanide hydrochloride was reported to proceed in a concentrated solution of hydrochloric or phosphoric acid in the presence of a radical initiator. Here we have studied the polymerization of allyl alcohol by a radical initiator in the presence of a Lewis acid (ZnCl₂, CuCl₂ or MgCl₂) in an organic solvent (toluene, hexane, methanol or isopropanol). Reactions were performed either at room temperature or 50°C under an atmosphere of nitrogen or in a sealed tube. The same polymerization was also carried out in water and in a concentrated acid solution. The polymer product was purified by dialysis in 0.2–3.7% yield and confirmed by elemental analysis, infrared spectroscopy and ¹H NMR. The molecular weight range of poly(allyl alcohol) was 10,000–35,000. The polymerization of allyl acetate by the radical initiator under the above conditions gave poly(allyl acetate) with the molecular weight range of 10,000–13,800 by multi‐angle laser light scattering. Copyright © 2007 John Wiley & Sons, Ltd.     

The microwave spectrum,chlorine nuclear quadrupole resonance spectrum and structure of propiolyl chloride

The microwave rotational spectra of the two most abundant isotopic species of propiolyl chloride have yielded rotational constants and nuclear quadrupole coupling constants. These, in combination with the chloride nuclear quadrupole resonance spectra, have yielded the molecular structure.     

The microwave spectrum,structure and dipole moment of 1,4-pentadiyne

The microwave spectra of 1,4-pentadiyne and 1,4-pentadiyne-1,5-d₂ are assigned and rotational and centrifugal distortion constants obtained. A unique structure could not be determined. However, analysis of the moments of inertia indicates that the bond distances in C₅H₄ are close to typical values found in other related compounds. An interaction involving the acetylene moieties is evidenced by the derived bond angles. The data are consistent with either the central CCC angle being close to the tetrahedral value with the acetylene groups pushed away from linearity by approximately 3–4° or opening of the central CCC angle to about 113° along with linear acetylene groups. A range of structures between these two is also possible. The dipole moment is determined to be 0.516(5) D.     

The vibrational spectrum and conformations of allyl chloride

Infrared and Raman spectra are reported for allyl chloride in vapour and liquid phases and also by matrix isolation in argon and nitrogen. Assignments are made in terms of a predominant low energy gauche form with a smaller amount of high energy cis form in all phases.     

The microwave spectrum,structure and centrifugal distortion constants of 2-chloroacrylonitrile

The microwave spectrum of 2-chloroacrylonitrile has been studied in the 26.5–40 GHz region. A total of 99 a- and b-type rotational transitions have been measured and assigned for CH₂ =C³⁵Cl(CN),yielding values for the rotational constants (in MHz): A = 6973.27, B = 3148.16, C = 2165.95. For CH₂=C³⁷Cl(CN) a total of 53 transitions have been measured and assigned and the rotational constants obtained are (in MHz): A = 6909.35, B = 3081.17, C = 2127.98. The distortion effects have also been studied and the quartic distortion constants have been evaluated. From the observed hyperfine structure, the chlorine nuclear quadrupole coupling constants have been obtained. The structure of vinyl cyanide and vinyl chloride can be transferred to account remarkably well for the observed rotational constants.     

Formation,microwave spectrum and preliminary structure of selenoketene

Hitherto unknown selenoketene, CH₂CSe, has been produced by pyrolysis of 1,2,3-selenodiazole and identified by observation of microwave absorption from CH₂C&.dbnd;⁸⁰Se and CH₂C⁷⁸Se. The CC and CSe bond lengths of selenoketene agree with bond lengths in ketene, CH₂CO, and in carbonyl sulphide, OCS.     

The microwave spectrum and structure of 1,1,1,3,3,3-hexafluoropropane,freon R236fa

The microwave spectra of three isotopic species of 1,1,1,3,3,3-hexafluoropropane (R236fa) (CF₃CH₂CF₃, ¹³CF₃CH₂CF₃ and CF₃¹³CH₂CF₃) were observed in the region from 4.5 to 18 GHz using a molecular beam Fourier transform microwave spectrometer (MB-FTMW). The rotational and centrifugal distortion constants were determined. The r_s (C–C) bond length and bond angle (C–C–C) of the molecule were determined to be 1.56(5) and 109(3) Å, respectively. The ab initio calculation of R236fa was executed at the MP2/6-31G(d,p) level. Comparison of the bond length and bond angle of R236fa with those in the other fluoropropanes revealed trends for the C–C bond length and CCC angle, depending on the number of fluorine atoms attached to the central carbon. A similar idea had been noted by Mack et al. from the electron diffraction studies of fluoropropanes.     

The microwave spectrum of tellurophene

The microwave spectrum of tellurophene, C₄H₄Te, has been recorded between 8 and 27 GHz. The rotational constants obtained from least-squares fitting of low-J lines are:

Figures in parentheses are uncertainties in last place of decimal (95% confidence limit). Corresponding inertial defects are 0.094 (7), 0.095 (6) and 0.097 (10) amu A² respectively, indicating the essential planarity of the molecule.Stark shift measurements correspond to a dipole moment of μ_a = 0.619 x 10^?30 C m (0.186 D).An approximate structure, based on bond lengths of CC and CH bonds adopted from related molecules, implies that r (Te - C) = 205.5 pm and ? C (5) TeC (2) = 82.53°.     

The microwave spectrum of selenoformaldehyde

The microwave spectra of the four major isotopic species of the unstable molecule selenoformaldehyde have been assigned. The limited number of isotopic variants yields the following structure: r(CSe) = 175.9 pm, ∠(HCH) = 120.4° and r(CH) assumed to be 109 pm. The dipole moment is 1.41 ± 0.01 D.     

Conformational study of allyl fluoride,allyl alcohol and allyl amine through the matrix-isolation technique

In a vibrational analysis of allyl compounds, which was made difficult because of autoassociation and conformational equilibrium, we have used the matr     

Estimation of allyl alcohol by chloramine-T

A simple but rapid and accurate method for the estimation of allyl in aqueous solution has been developed, based on its oxidation with chloramine-T at room temperature, in 0.5-1.0M hydrochloric acid medium. The reaction involves a two-electron change. The effect of such variables such as pH of the medium, presence of foreign ions and perchloric or sulphuric acid on the rate of oxidation is discussed.     

The microwave absorption spectrum of MgO

The microwave absorption spectrum of ²⁴MgO, ²⁵MgO and ²⁶MgO has been observed in the frequency range between 67 and 275 GHz. Quadrupole hyperfine structure of ²⁵MgO was partially resolved. The molecular constants derived from these measurements are two orders of magnitude more accurate than previous MODR results.     

The microwave spectrum of argon-phosphorus trifluoride

The argon-PF₃ complex has been prepared in a supersonic expansion of Ar (98%) and PF₃ (2%). A Fourier-transform micro-wave spectrometer employing a Fabry-Pérot cavity was used to assign 28 rotational transitions. The rotational constants (MHz) and distortion constants (kHz) were A = 7332.468(10), B = 1023.055(2), C = 952.564(2), D_J = 3.53(1), D_JK = 60.4(1) and d₁ = −0.240(7). The argon atom is 3.953 Å (r_c.m.) from the PF₃ center of mass and r_c.m. makes an angle of 70.3° with the C₃ axis of the PF₃.     

The microwave spectrum of chloroacetyl chloride

The microwave spectrum, rotational constants and centrifugal distortion parameters for CH₂³⁵ClCO³⁵Cl are reported. The nuclear quadrupole coupling constants of the two non-equivalent Cl atoms were determined from partially resolved quadrupole splittings. The molecule is planar in the conformation studied here and both Cl atoms occupy the trans position as shown from their substitution coordinates.     

The microwave spectrum of dichloroacetic acid

The microwave spectrum of dichloroacetic acid consists of many weak absorption lines, of which only a small number has been identified. From the measured frequencies only two rotational constants could be obtained. Determination of the nuclear quadrupole coupling constants of the two chlorine atoms was not possible, since no line splittings were observed.Isotopic substitution of the two chlorine and the two hydrogen atoms shows that the assigned absorption lines belong to the conformation with the hydrogen atom gauche with respect to the hydroxylic group, while the carboxylic group has the common trans geometry. Substitution of the hydrogen atom of the dichloromethyl group by deuterium decreases the inertial moment I_c by 0.2 u Ų, indicating that structure determinations can be hampered by vibrational effects to an almost incredible extent.     

The microwave spectrum of acetaldehyde cyanohydrin

The microwave spectrum of acetaldehyde cyanohydrin shows two series of μ_aR branch transitions of almost equal intensity which are accompanied by similar patterns of vibrational satellites. The most probable explanation of these two series of lines consistent with the expected conformational behaviour of acetaldehyde cyanohydrin is that they belong to the two non-equivalent rotamers in which the hydroxyl group is gauche to the cyanide group.