3899-71-6Relevant articles and documents
Multistep Collisional Deactivation of Highly Vibrationally Excited 1,1,2,2-Tetrafluorocyclopropane
Arbilla, G.,Ferrero, J. C.,Staricco, E. H.
, p. 3906 - 3911 (1983)
The reaction of CH2(1A1) with C2F4 was investigated at 298 K and pressures between 66 and 1837 torr.Chemically activated 1,1,2,2-tetrafluorocyclopropane was formed with an energy of about 41 kcal/mol above the threshold energy for decomposition to CF2 and CF2CH2.A significant dependence of the experimental specific rate constant for unimolecular decomposition with pressure was observed and is indicative of a multistep collisional deactivation process.The data could be fitted to a stepladder model, with down-energy loss of about 9 kcal/mol and with a minimum energy for the activated molecule of 85 +/-2 kcal/mol.In these experiments C2F4 is the major collision partner and the limiting high-pressure region could not be reached.With this value and the known heats of formation of CH2(1A1) and C2F4, the heat of formation of tetrafluorocyclopropane was estimated to be ΔHfo ca. -140 kcal/mol.
The Microwave Spectra, Electric Dipole Moment, and Molecular Structure of 1,1,2,2-Tetrafluorocyclopropane
Beauchamp, R. N.,Gillies, C. W.,Craig, N. C.
, p. 1696 - 1701 (2007/10/02)
The microwave spectra of the normal, monodeuteriated, dideuteriated, and carbon-13 isotopic species of 1,1,2,2-tetrafluorocyclopropane heve been investigated and assigned in the region 26.5-40.0 GHz.The spectral assignments have yielded sufficient data to enable a complete determination of the molecular geometry in the frameworks of both the normal and dideuteriated isotopic species.The partial rs parameters in the framework of the normal isotopic species are r(C1C2) = 1.471(3) Angstroem, r(C3C1,2) = 1.497(10) Angstroem, r(C1,2F) = 1.344(40 Angstroem, r(C3H) = 1.088(5) Angstroem, θ(FC1,2F) = 109.9(4) deg and θ(HC3H) = 118.)(4) deg.The electric dipole moment is determined to be 2.16(3) D.The rotational spectra and symmetry of two low lying vibrational modes were assigned in the dideuteriated isotopic species.The frequencies of the modes were determined from relative intensity measurements to be 188(9) cm-1 for the symmetric (A) vibrational state and 178(13) cm-1 for the antisymmetric (B) vibrational state in accord with the previous vibrational assignments.All the ring bonds in 1,1,2,2-tetrafluorocyclopropane are found to shorten relative to cyclopropane with the greater reduction occurring in the C1-C2 bond.The FCF and HCH methylene angles, however, are larger in 1,1,2,2-tetrafluorocyclopropane than in 1,1-difluorocyclopropane.These results are related to structural trends established by several experimental and theoretical studies which examined the effect of fluorine substitution on the geometry of substituted cyclopropanes and oxiranes.
