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

Abstract

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 r_e(PO) 145.3 pm, r_e(PF) 157.3 pm and θ_e(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 Geometry of FPS

“…Specifically, five different valence basis sets (VTZ + 1, VQZ + 1, V5Z, AVQZ + 1, AV5Z), which have been defined in our previous study on FPO (23), were employed. For each of these sets, the basis functions for sulfur were chosen in complete analogy to those for phosphorus (23).…”

“…Very recently we reported on combined ab initio, gas phase high-resolution infrared (IR), and millimeter-wave (MMW) spectroscopic investigations, as well as on lifetime measurements of FPO (23). Despite the substantial spectroscopic and structural data on gaseous oxophosphines which now have become available, no related investigations on thioxophosphines (thiophosphanes) have been reported except for a preliminary communication (24) of our studies on FPS.…”

“…Unlike the very common derivatives having fourcoordinate phosphorus (X 3 PO), oxophosphines and related species should contain a phosphorus-chalcogen double bond essentially formed by p orbitals. The presence of such double bonds has been deduced from ab initio calculations (15), inferred from their high chemical reactivity (14), and only recently confirmed by structural parameters obtained from rotational and rovibrational spectra of oxophosphines (16)(17)(18)(19)(20)(21)(22)(23) in the gas phase.…”

“…In analogy to the generation of SSiF 2 (27) and OPF (22,23) by flash pyrolysis of F 3 SiSSiF 3 and F 2 POPF 2 , respectively, FPS has been obtained from F 2 PSPF 2 in Ar at temperatures higher than 1400…”

Anharmonic force fields of perchloric acid, HClO4, and perchloric anhydride, Cl2O7. An extreme case of inner polarization

“…On the one hand, one of his research interests over the years has been high-resolution IR spectroscopy on second-row compounds, such as SiHF 3 [26], FPO [27], FPS [28], HNSO [29], SO 2 F 2 [30], and many others, as well as ab initio and DFT electronic structure studies on such systems (e.g., [31,32]) and combined theoretical-experimental studies (e.g., on allyl phosphine [33]). On the other hand, Dr. Demaison and one of the present authors are fellow members in a IUPAC Task Group on the thermochemistry of radicals and other transient atmospheric and combustion species [34].…”