Millimeter-Wave Spectra, ab Initio Calculations, and Structures of Fluorophosphane and Chlorophosphane

The structures of fluorophosphane, PH2F, and chlorophosphane, PH2Cl, have been calculated ab initio at the SCF, MP2, CCSD, and CCSD(T) levels using a quadruple ζ polarized basis set. Equilibrium and ground state rotational constants as well as centrifugal distortion constants have been predicted for several isotopomers of PH2F and PH2Cl. Theoretical CCSD(T) geometries were also determined for the series of PHnX3-n (X = F, Cl; n = 0−3) molecules using a triple ζ polarized basis set. The millimeter-wave spectra of the short-lived molecules PH2F, PH2Cl, and their perdeuterated species were measured in the frequency range 100−470 GHz. For PH2F and PH2Cl, accurate ground state parameters have been obtained by a combined fit of the millimeter-wave data and the infrared ground state combination differences. The ro, rz, and re structures of PH2F and PH2Cl, as well as PH3, PCl3, and PHF2 have been determined. The experimental results are found in excellent agreement with their ab initio predictions

Ab initio calculations on monohalogenophosphanes PH₂X (X=F,Cl,Br,I), and experimental detection and characterization of PH₂F and PH₂Cl by high resolution infrared spectroscopy

The harmonic and anharmonic force fields of the title compounds have been calculated at the ab initio self‐consistent‐field level using effective core potentials and polarized double‐zeta basis sets. Additional calculations for PH2F employ larger basis sets and include electron correlation. Many rovibrational constants are predicted theoretically. The infrared spectra generated from the ab initio data have guided the experimental identification of PH2F and PH2Cl in the gas phase. High resolution Fourier transforminfrared spectra of these unstable molecules have been recorded for the first time. Rotational analyses for several bands are reported which provide accurate ground state constants and a precise characterization of a number of vibrationally excited states. The accuracy of the ab initio predictions for PH2F and PH2Cl is evaluated by comparisons with these experimental data

Analysis of the rotation-vibration in the ν2=1,ν3=1\nu_{2} = 1, \nu_{3} = 1 and ν6=1\nu_{6} = 1 states of CDF3CDF_{3}

$^{1}$R. Bocquet, D. Boucher, W. D. Chen, D. Papousek, G. Wlodarczak and J. Demaison, J. Mol. Spectrosc. 163, 291-299 (1994)Author Institution: Université de Lille 1, 59655 VILLENEUVE D'ASCQ France; Universität-Gesamthochschule, FB 9, D 42037 WUPPERTAL, Germany; "Abteilung Chemische Physik, Universität Kiel", Olshausenstrasse 40-60, D 24098 KIEL GermanyThe infrared spectra of the $\nu_{2}$ and $\nu_{3}$ fondamental bands of $CDF_{3}$ have been recorded with a high resolution $(0.003 cm^{-1})$ FTIR spectrometer (BRUKER IFS 120HR). The K structure was analysed up to J = 50 for both states : 2488 lines of $\nu_{2}$ and 1956 lines of $\nu_{3}$ were assigned. We added also results from a previous analysis of millimeter-wave spectra of the ground, $\nu_{2} = 1$ and $\nu_{3} = 1$ $states^{1}$. Rotational constants and quartic and sextic centrifugal distorsion parameters have been determined accurately. These parameters are much more precise than those reported in previous works. The rotational spectrum of the $\nu_{6} = 1$ state was measured up to 500 GHz and direct $\ell-type$ resonance transitions were observed between 2 and 24 GHz. Two different sets of parameters were used to fit the data because the effective Hamiltonian may be reduced in different ways. The unitary equivalence of both sets of parameters is verified

FP=S in the gas-phase: Detection by rotationally resolved infrared and millimetre-wave spectra assisted by ab-initio calculations

Pyrolysis of F2PSPF2 at about 1400 °C in Ar flow provides a new and practical method for synthesising short-lived FP=S (with side product PF3). Cooperation between infrared and millimetre-wave (MMW) spectroscopy assisted by reliable ab-initio calculations at the MP2 and CCSD(T) levels has led to the gas-phase detection of this elusive species and enabled its spectral characterisation. The excellent agreement of all methods confirms the identification. The IR data provide parameters for the v1 = 1 vibrational state. From the MMW data it was possible to calculate precise ground state parameters up to the sextic centrifugal distortion terms

MILLIMETER WAVE, INFRARED AND AB INITIO STUDY OF FPS

Author Institution: Anorganische Chemie, FB 9, Universit\""{a}t GH; Anorganische Chemie, FB 9, Max-Plank-Institut f\""ur Kohlenfsorschung; Physique des Lasers, Atomes et Mol\'{e}cules Centre d' Etudes et de Recherches Lasers et Applications, Universiti\'{e} des Sciences et Technologies de LilleWe show how a collaborative study involving ab initio calculations, chemistry, rovibrational spectroscopy and pure rotational spectroscopy can successfully be used to predict, produce, identify and characterize new short-lived molecular species. Ab-initio calculations at the MP2 and CCSD(T) level with VQZ1+ basis set were carried out using GAUSSIAN98 and MOLPRO98 programs in $M\""{u}hlheim$. FPS was produced by pyrolysis of $F_{2}PSPF_{2}$ synthesized at Wuppertal and the rotationally resolved $\nu_{1}$ band then identified by FTIR spectroscopy. Accurate rotational and centrifugal distortion constants in the ground state were determined using millimeter wave spectroscopy in Lille. Measurements of the $^{34}S$ isotopomer and $\nu_{3}$ vibrationally excited state will allow an experimental approximation to the equilibrium structure

Millimeter-wave spectroscopy, high resolution infrared spectrum, ab initio calculations, and molecular geometry of FPO

The transient FPO molecule was produced in a flow by pyrolysis of 5% F2POPF2 in Ar at 1300–1400°C. High resolution (0.008 cm−1) Fourier transform infrared spectra of the a-type ν1 and ν2 bands centered at 1297.54 and 819.57 cm−1, respectively, were measured and fitted to excited state parameters up to quartic centrifugal distortion constants. Millimeter-wave spectra between 300 and 370 GHz of FPO in the ground and ʋ3 = 1 excited states were recorded, and 124 and 86 lines, respectively, including for both states a- and b-type transitions, were measured and fitted to a Watson A-type Hamiltonian up to sextic centrifugal distortion terms. High-level ab initio calculations with large basis sets were performed for FPO to provide reliable structural parameters as well as harmonic [CCSD(T)/AVQZ + 1] and anharmonic [MP2/VQZ + 1] force fields up to quartic terms. The spectroscopic constants derived from these force fields are generally in excellent agreement with experiment. The calculations moreover suggest anharmonic interactions between ν2 and 2ν3, and between ν1 and ν2 + ν3. Deperturbation of the ʋ1 = 1 and ʋ2 = 1 levels was done, and the results are in support of a band center of ν3 close to 412 cm−1. Consistent experimental and theoretical equilibrium structures were determined for FPO, with re(PO) 145.3 pm, re(PF) 157.3 pm and θe(FPO) 110.1°. The collision-controlled 1/e life-time of FPO generated by an electric discharge in an F2POPF2/Ar mixture at 8–10 Pa and at room temperature is 8 ms

Millimeter-Wave Spectroscopy, High Resolution Infrared Spectrum, Ab Initio Calculations, and Molecular Geometery of FPS

The transient thiophosphenous fluoride FPS was produced by pyrolysis of 2.5% F2PSPF2 in Ar at 1300–1800°C. High-resolution (≥0.004 cm−1) Fourier transform infrared spectra of the a-type ν1 and b-type ν2 bands, centered respectively at 803.249 and 726.268 cm−1, were measured and fitted to rotational and quartic centrifugal distortion parameters. The millimeter-wave spectrum, essentially b-type, was measured between 300 and 370 GHz in the ground state and in the ν3 excited state for FP32S and in the ground state for FP34S. The frequencies were fitted to a Watson-type A-reduced Hamiltonian up to sextic distortion terms. High level ab initio calculations with large basis sets were performed on FPS and supported the first identification of its infrared and millimeter wave spectra. The calculated anharmonic force field provided precise ab initio rovibrational α constants which were combined with the experimental molecular parameters to determine an accurate equilibrium structure of the molecule: re(PS)=188.86 pm, re(PF)=158.70 pm, θ(FPS)=109.28°. The collision-controlled 1/e lifetime measured in a 10-Pa (1 : 20) F2PSPF2/Ar mixture was 2 s, more than two orders of magnitude larger than that of FPO under the same experimental conditions