Spectra and structure of organophosphorus compounds. XXXIII. Microwave, infrared, and Raman spectra, structure, conformational stability, and vibrational assignment for ethylphosphonothioic difluoride

Abstract

The microwave spectra of ethylphosphonothioic difluoride, CH3CH2P(S)F2, and eight isotopic species have been investigated in the region from 26.5 to 39.5 GHz. Only a-type transitions were observed and R-branch assignments have been made for all the isotopic species in the ground vibrational state for both the gauche and trans (methyl group trans to the P=S bond) conformers from which the rotational constants were determined. From these data the complete r0 structural parameters were determined for the gauche conformer with the values for the heavy atom parameters being: r(C–C)=1.532±0.006 Å, r(C–P)=1.800±0.007 Å, r(P=S)=1.880±0.003 Å, r(P–F)=1.555±0.005 Å, ∢CCP=112.6±0.3°, ∢CPS=119.4±0.4°, ∢CPF=102.0±0.2°, dih ∢FPCS=129.3±0.2°, and dih ∢CCPS=56.9±0.2°. The parameters of the trans conformer which differed significantly from the values for the corresponding ones in the gauche conformer were: r(C–P)=1.814±0.011 Å, r(P=S)=1.861±0.007 Å, and ∢CCP=114.8±0.2°. The infrared (3500 to 40 cm−1) and Raman (3500 to 20 cm−1) spectra of the gaseous and solid CH3CH2P(S)F2 and CD3CD2P(S)F2 as well as the Raman spectrum of the liquid have been recorded. Both trans and gauche conformers have been identified in the vibrational spectra of the fluid phases, but only the trans corformer remains in the solid state and a complete vibrational assignment is proposed for the trans conformer. The barrier to methyl rotation for the trans conformer was determined to be 808 cm−1 (2.31 kcal/mol). The asymmetric torsion for the trans conformer was observed as a series of closely spaced Q branches beginning at 73.25 cm−1 and falling to lower frequency and the gauche transitions begin at 70.82 cm−1. These transitions along with the dihedral angle for the gauche conformer have been used to obtain the potential function for the asymmetric rotation which indicates that the trans conformer is more stable than the gauche conformer in the gas phase by 63±37 cm−1 (180±106 cal/mol). All of these results are compared with corresponding quantities for several similar organophosphorus compounds.

Synthesis of Ternary CuInS2 Nanocrystals; Phase Determination by Complex Ligand Species

“…Figure shows the spectra concerning the sulfur component. Upon dissolution of the sulfur in TPOP, two new bands at 944 and 800 cm −1 (hatched area in Figure b) appeared; the band at 944 cm −1 was attributed to the ν P−O , and the band at 800 cm −1 was attributable to the stretching mode of the PS bond, , ν PS . The two newly appeared bands are evidence for the coordination of sulfur with TPOP.…”

Spectra and structure of organophosphorus compounds: XLIX. Microwave, infrared, and Raman spectra, electric dipole moment, molecular structure, and ab initio calculations of dimethylphosphonothioic fluoride

“…From an assumed molecular structure for (CH3)2PSF, based on structural parameters previously reported for OPF 3 [5], SPF 3 [6], CH3PSF 2 [3], CH3CH2PSF 2 [4], and (CH3)3PS [11,12], calculation shows that (CH3)2PSF is a near prolate rotor (r = -0.84) and its symmetry plane contains the a and c inertial axes with the b axis perpendicular to the plane of symmetry. As the dipole moment of the molecule must lie between the a and c inertial axes, only a-and c-type R and Q branch transitions are expected to occur.…”

Microwave Spectra, ab Initio Calculations, and r0 Structural Parameters for (Methylamino)thiophosphoryl Difluoride

“…The structure and the conformational stabilities of phosphorus molecules which contain the -P(dS)F 2 group are of interest to chemists. [1][2][3][4][5][6][7][8] For ethylthiophosphoryl difluoride, CH 3 CH 2 P-(dS)F 2 , there is little difference between the conformational stabilities of the two forms where the gauche conformer (CH 3 group gauche to PdS bond) was determined to be more stable than the trans conformer (CH 3 group antiperiplanar to PdS bond) by 63 ( 37 cm -1 (0.75 ( 0.44 kJ/mol) from the microwave study 3 which is consistent with the more recently determined value 5 of 53 ( 7 cm -1 (0.63 ( 0.08 kJ/mol) from variable-temperature studies of krypton solutions by utilizing infrared spectral data. However, when the terminal methyl group is replaced by a halogen atom, the experimentally determined order of stability is reversed with values of 244 ( 16 cm -1 (2.92 ( 0.19 kJ/mol) for ClCH 2 P(dS)F 2 in the krypton solution 7 and 250 ( 20 cm -1 (2.99 ( 0.24 kJ/mol) for FCH 2 P(dS)F 2 in the liquid phase, 8 both having the trans conformer as the more stable form.…”