Perfluoro-1,2-dioxolane. A new synthesis and its gas-phase structure (original) (raw)
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A new approach to the synthesis of 2,2-difluoro-1,3-dioxolanes
Journal of Fluorine Chemistry, 1995
A direct and versatile way to prepare halogenated 2,2-difluoro-l,3-dioxolanes through the addition of bis-(fluoroxy)difluoromethane (BDM) to halogenated alkenes (CF2=CFCF3, CF2=CFOCF2CF3, CF2=CHCF3, CF3CF=CFCF3, CFCI = CFCI, CFBr = CFBr, CCI2= CCI2, CHCl = CCi2, CHCI = CHCI, CH 2 = CHCI, CF 2 = CFCI, (CF3)2CFCF = CFCF3, CF2 = CFBr, CF2=CF2) has been discovered.
Structural Analysis of Perfluoropropanoyl Fluoride in the Gas, Liquid, and Solid Phases
The journal of physical chemistry. A, 2016
The coexistence of two conformers in perfluoropropanoyl fluoride, CF3CF2C(O)F, differing in the CC-CF dihedral angle (gauche 85(10)% and anti 15(10)%), has been determined by means of gas-phase electron diffraction (GED). Quantum-chemical calculations performed at the MP2 and B3LYP approximations and cc-pVTZ basis sets reproduce the experimental values with confidence. By contrast, FTIR spectra give no clear evidence for the anti-conformer in the gas phase. Information on this less abundant but stable rotamer is obtained from matrix-isolation/FTIR spectroscopy and liquid Raman spectroscopy. In situ crystallization and single-crystal X-ray diffraction (XRD) data reveal the presence of solely the gauche-conformation in the solid state. A set of intermolecular interactions including C═O···C═O, C-F···F-C, and F···C═O is detected. The nature of bonding and the relative stabilities of gauche- and anti-conformers are explored using natural bond orbitals.
Inorganic Chemistry, 1986
Me2NCN)(SN)2, generated in situ from 2a. To test this possibility we added a solution of 2a in CC14 to a green solution of (NSCl)3 in CC14 at 60 0C.29 However, this reaction resulted in the dechlorination of (NSC1)3 by 2a to give S4N4 and la. An alternative mechanism for the production of 3a involves the formation of the monosubstituted derivative of la, (Me,NCN)(NSCl)(NSNSO), which undergoes intermolecular elimination of SO2 to give RN=S=NR (where R = (Me2NCN)(NSCl)(NS)). When R = (Ph2PN)2(SN), this type of compound readily undergoes a six-to eight-membered-ring expansion to give a spirocyclic compound, which forms a monocyclic eight-membered ring on thermal decomposition.M A similar sequence of transformations could account for the formation of h3'
Fluorofluoroxydioxirane and Other CF 2 O 3 Isomers
The Journal of Physical Chemistry A, 2001
Seven structural isomers, and relevant transition states, on the lowest-energy spin-singlet potential energy surface of CF 2 O 3 are characterized using correlated ab initio electronic structure methods. On the basis of preliminary comparative calculations, second-order Møller-Plesset perturbation theory with a correlationconsistent polarized valence double-one-electron basis set (MP2/cc-pVDZ) was chosen with which to describe equilibrium structures and harmonic vibrational frequencies of all relevant rotamers. Accurate energy differences were determined using the coupled cluster method, with perturbative inclusion of triple excitations, and a valence triple-basis (CCSD(T)/cc-pVTZ). The lowest energy isomer is predicted to be the molozonide of difluorocarbene, whose adiabatic decay is prevented by a sizable barrier. Plausible mechanisms for the isomerization of the titled compound to the low-energy fluoroformyl peroxyhypofluorite and nearly isenergetic carbonyl hypofluorite are suggested. An analogous reaction path may be of importance to the isomerization of difluorodioxirane (CF 2 O 2 ) and is included in the study.
Cheminform, 1992
The geometric structures and conformational compositions of malonyl difluoride, COF-CH2-COF (l), and difluoromalonyl difluoride, COF-CF,-COF (Z), were studied by gas electron diffraction and ab initio calculations (HF/3-21G and HF/6-31G**). The experimental scattering intensities of both compounds are reproduced best by mixtures of two conformers with aplanar skeletons and the C=O bonds eclipsed with respect to vicinal single bonds (C-C, C-H or C-F). The main conformer of I possesses CI symmetry with one COF group rotated by GI(CCCO) = 112 (2)' and the other COF group lying in the CCC plane (S,(CCCO) = Oo, i.e. C=O cis to C -C ) . The presence of a small amount (10 (IO)%) of a second conformer with C2 symmetry and with both C=O bonds eclipsing the C-H bonds is likely. The relative stabilities of the two conformers of 2 are reversed. The low-energy form possesses C, symmetry with both COF groups rotated by 120 ( 2 ) O , and the high-energy form (30 (1 9%) possesses CI symmetry with one C=O bond eclipsing one vicinal C-F bond and the other C=O bond eclipsing the opposite C-C bond. The ab initio calculations predict the experimentally determined conformations with C1 and C, symmetry to be stable structures, and their relative stabilities depend on the size of the basis set. The large basis set predicts the correct relative energies for 1 and the small basis set for 2. Experimental bond lengths and bond angles are reproduced very well by the HF/3-21G method.
The Journal of Physical Chemistry A, 2004
The geometric structure and conformational properties of 4-fluoro(trifluoromethoxy)benzene, 4-F-C 6 H 4 OCF 3 , were investigated independently in two laboratories (Moscow State University and Universität Tübingen) using gas electron diffraction (GED), quantum chemical calculations, and matrix infrared spectroscopy. Both experimental GED studies result in a perpendicular conformation (C-O-C plane perpendicular to the benzene ring). Analyses of the GED intensities with a simple two-conformer model cannot exclude a small contribution of up to 25% (Moscow) or 13% (Tübingen) of a planar conformer. Quantum chemical calculations lead to rather different potenial functions for internal rotation around the C(sp 2 )-O bond. HF, MP2, and B3LYP methods with 6-31G* basis sets predict potential functions with a single minimum for perpendicular orientation. The planar structure is predicted to correspond to a transition state, 0.6-1.8 kcal/mol higher in energy. B3LYP/ cc-pVTZ calculations predict an additional very shallow minimum for the planar conformer, about 0.6 kcal/ mol higher than that for the perpendicular structure. Infrared spectra demonstrate the presence of a single conformer in a Ne matrix at 15 K and no second conformer is expected to be present in the gas phase, assuming an adiabatic cooling process.
Inorganic Chemistry, 2004
Pure fluorocarbonyl trifluoromethanesulfonate, FC(O)OSO 2 CF 3 , is prepared in about 70% yield by the ambienttemperature reaction between FC(O)SCl and AgCF 3 SO 3 . The geometric structure and conformational properties of the gaseous molecule have been studied by gas electron diffraction (GED), vibrational spectroscopy [IR(gas), IR(matrix), and Raman(liquid)] and quantum chemical calculations (HF, MP2, and B3LYP with 6-311G* basis sets); in addition, the solid-state structure has been determined by X-ray crystallography. FC(O)OSO 2 CF 3 exists in the gas phase as a mixture of trans [FC(O) group trans with respect to the CF 3 group] and gauche conformers with the trans form prevailing [67(8)% from GED and 59(5)% from IR(matrix) measurements]. In both conformers the CdO bond of the FC(O) group is oriented synperiplanar with respect to the S−O single bond. The experimental free energy difference between the two forms, ∆G°) 0.49(13) kcal mol -1 (GED) and 0.22(12) kcal mol -1 (IR), is slightly smaller than the calculated value (0.74−0.94 kcal mol -1 ). The crystalline solid at 150 K [monoclinic, P2 1 /c, a ) 10.983(1) Å, b ) 6.4613(6) Å, c ) 8.8508(8) Å, ) 104.786(2)°] consists exclusively of the trans conformer.
Inorganic Chemistry, 1989
Registry No. cis-1 (R" = H, Rs = H), 87678-58-8; trans-1 (R" = H, RP = H), 87678-57-7; cis-1 (R" = F, R@ = H), 122049-31-4; trans-1 (R" = F, RB = H), 122049-48-3; cis-1 (R" = CI, Rs = H), 122049-32-5; trans-1 (R' = CI, RS = H), 122049-49-4; cis-1 (R" = OH, RP = H), 122049-33-6; rrans-1 (R" = OH, R@ = H), 122049-50-7; cis-1 (R" = NHz, Rs = H), 122049-41-6; trans-1 (R" = NH2, Rs = H), 122049-51-8; cis-1 (R" = CH,, R@ = H), 122049-42-7; trans-1 (R" = CH,, R@ = H), 122049-52-9; cis-1 (R" = SiH,, Rs = H), 122049-43-8; trans-1 (R" = SiH,, R@ = H), A gas-phase electron diffraction study of perfluoro-2,3-diaza-l,3-butadiene results in a planar trans structure with the following geometric parameters (ra values with 30 uncertainties): N-N = 1.421 (12), C=N = 1.264 (7), C-F = 1.304 (4) A; N-N=C = 112.7 (9), F-C-F = 110.8 ( 9 ) ' . The CF2 groups are tilted by 5.0 (8)' toward the nitrogen lone pairs. No additional conformer has been observed. Ab initio calculations for CH2=N-N=CHz (6-31G8* basis) and CFz=N-N=CF2 (6-31G* basis)