caa a22 4500 469072350 CHVBK 20180323132925.0 cr unu---uuuuu 170328e19921001xx s 000 0 eng 10.1007/BF00678557 doi (NATIONALLICENCE)springer-10.1007/BF00678557 Spectra and structure of small ring compounds. LIX [Elektronische Daten] Raman and far infrared spectra, conformational stability, vibrational assignments, normal coordinate analysis, and ab initio calculations of fluorocyclobutane [J. Durig, Min Lee, Wenyun Zhao, T. Little] The Raman (3200 to 10 cm−1) and far infrared (380 to 60 cm−1) spectra of gaseous fluorocyclobutane,c-C4H7F, have been recorded. A series of Q-branches observed in both of these spectra beginning at 166 cm−1 with successive transitions falling to lower frequencies have been assigned to the ring puckering vibrations of both the low energy equatorial and high energy axial conformers. These data have been fit to an asymmetric potential function of the form:V (cm−1)=(1.76±0.05)103X+(4.88±0.28)104X2+(2.12 ±0.16)103 exp(−5.66±0.41)10X2 with a reduced mass function ofg 44= 0.00386−0.00295X+0.03485X2+0.1228X3 +0.3459X4, whereX is the ring puckering coordinate. Utilizing this potential, the difference between the puckering angles for the two conformers was calculated to be 4° with the equatorial conformer having the larger value of 28°. This potential function is consistent with an energy difference between the equatorial and axial forms of 447 cm−1 (1.28 kcal/mol) and a barrier to ring inversion from the equatorial to the axial conformation of 713 cm−1 (2.04 kcal/mol). Experimental values for the enthalpy difference between the two conformers have been determined for both the liquid (400±30 c−1) and gas (413±43 cm−1) from investigations of the Raman spectra at variable temperatures. The conformational stability, enthalpy difference, structural parameters, and fundamental vibrational frequencies, which have been determined experimentally, are compared to those obtained from ab initio Hartree-Fock calculations employing the 3-21G, 6-31 G*, and 6-31 G** basis sets. Plenum Publishing Corporation, 1992 Durig J. Department of Chemistry, University of South Carolina, 29208, Columbia, South Carolina, USA aut Lee Min Department of Chemistry, University of South Carolina, 29208, Columbia, South Carolina, USA aut Zhao Wenyun Department of Chemistry, University of South Carolina, 29208, Columbia, South Carolina, USA aut Little T. Department of Chemistry, University of South Carolina, 29208, Columbia, South Carolina, USA aut Structural Chemistry Kluwer Academic Publishers 3/5(1992-10-01), 329-345 1040-0400 3:5<329 1992 3 11224 https://doi.org/10.1007/BF00678557 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00678557 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Durig J. Department of Chemistry, University of South Carolina, 29208, Columbia, South Carolina, USA aut NATIONALLICENCE 700 1- Lee Min Department of Chemistry, University of South Carolina, 29208, Columbia, South Carolina, USA aut NATIONALLICENCE 700 1- Zhao Wenyun Department of Chemistry, University of South Carolina, 29208, Columbia, South Carolina, USA aut NATIONALLICENCE 700 1- Little T. Department of Chemistry, University of South Carolina, 29208, Columbia, South Carolina, USA aut NATIONALLICENCE 773 0- Structural Chemistry Kluwer Academic Publishers 3/5(1992-10-01), 329-345 1040-0400 3:5<329 1992 3 11224 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer