Microwave Spectrum, Conformational Composition, and Dipole Moment of (Fluoromethyl)cyclopropane (C₃H₅CH₂F)

Abstract

The microwave spectrum of (fluoromethyl)cyclopropane, C3H5CH2F, has been investigated in the whole 12-75.6 GHz spectral range. Many measurements were also performed in the 75.6-120 GHz region. The spectra of two conformers were assigned. The H-C-C-F chain of atoms is antiperiplanar in the conformer denoted ap and synclinal in the sc rotamer. The sc conformer has a lower energy than ap. The internal energy difference was determined to be E(ap) - E(sc) = 1.7(8) kJ/mol from relative intensity measurements. The spectra of the ground vibrational state and seven vibrationally excited states belonging to two different normal modes were assigned for sc. The frequencies of these two modes were determined by relative intensity measurements. The dipole moment of this conformer was determined to be μ(a) = 5.520(17), μ(b) = 3.475(29), μ(c) = 0.35(13), and μ(TOT) = 6.532(40) × 10(-30) C m [1.958(12) D]. The spectrum of the ground vibrational state was assigned for ap. The microwave work was supported by quantum chemical calculations at the CCSD/cc-pVQZ, MP2/cc-pVTZ, and B3LYP/cc-pVTZ levels of theory.

On the reactivity of naphthalene and biphenyl dianions: tying up loose ends concerning an SN 2-ET dichotomy in alkylation reactions

“…Then that crude organic mixture was further purified (to >95%) by treating it with Cp* 2 ZrH 2 , but no spectroscopic evidence of purity was either reported . Finally, two recent articles with syntheses inspired in this paper have also been published, including a detailed experimental section in the most recent one, although no evidence of its isomeric purity . The synthesis of cyclopropylmethyl fluoride by nucleophilic fluorination of an appropriate cyclopropylmethyl derivative initially confronted us with an additional problem: the easy cationic isomerization of this structure.…”

“…[16] Finally, two recent articles with syntheses inspired in this paper have also been published, [17] including a detailed experimental section in the most recent one, although no evidence of its isomeric purity. [18] The synthesis of cyclopropylmethyl fluoride by nucleophilic fluorination of an appropriate cyclopropylmethyl derivative initially confronted us with an additional problem: the easy cationic isomerization of this structure. It occurs via the cyclopropylmethyl carbocation triad, which includes the cyclobutyl and 3-butenyl cations.…”

Synthesis, Microwave Spectrum, Quantum Chemical Calculations, and Conformational Composition of the Novel Compound Cyclopropylethylidynephosphine (C3H5CH2C≡P)

“…In one of these, the H–C–C–X link of atoms is antiperiplanar ( ap , dihedral angle = 180°), whereas the second conformer has a synclinal ( sc , dihedral angle ≈ 60°) conformation for this chain. Many C 3 H 5 CH 2 X compounds including X = F, − Cl, ,− Br, ,,, I, , OH, SH, SeH, NH 2 , PH 2 , CH 3 , SiH 3 , − SiF 3 , ,, CN, , CC–H, , and NC have been investigated by microwave (MW), infrared (IR), and/or Raman spectroscopy in the past often in conjunction with quantum chemical calculations.…”