Deformation of the benzene ring upon fluorination: Equilibrium structures of all fluorobenzenes

Jean Demaison, Heinz Dieter Rudolph, A. Császár

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Born-Oppenheimer equilibrium structure (r BO e) estimates are reported for benzene and all 12 possible fluorobenzenes, based on geometry optimizations performed at the coupled cluster level of electronic structure theory including single and double excitations augmented by a perturbational estimate of the effects of connected triple excitations [CCSD(T)] and Gaussian basis sets of at least triple zeta quality. Furthermore, accurate semiexperimental equilibrium (r SE e) structures are determined for C6H6 C6H5F, and 1,2-and 1,3-difluorobenzene. They are obtained through a least-squares structural refinement procedure based on equilibrium rotational constants of as many isotopologues as feasible, determined by correcting experimental vibrationally averaged ground-state rotational constants with computed ab initio vibration-rotation interaction constants and electronic g-factors, and using a few structural constraints based on the best r BO e estimates. The r BO e and r SE e equilibrium structures are in excellent agreement with each other for the four semirigid molecules but in almost all cases they differ significantly from previously determined equilibrium structure estimates based on rotational spectroscopy or gas electron diffraction. The nature of deformations of the benzene ring induced by a single fluorine substitution can be characterized as follows: (a) the strongest effect is the pushing of the ipso carbon atom toward the ring center resulting in a deformation at the ipso [by +2.7(1)°] and ortho [-1.7(1)°] CCC angles, (b) a simultaneous decrease in the ortho CC bond length of the benzene ring by 0.009 Å and (c) a decrease of all the CH bond lengths. Additivity relations concerning the F substitution effects are obtained based on the equilibrium structures of all possible fluorobenzenes.

Original languageEnglish
Pages (from-to)1539-1562
Number of pages24
JournalMolecular Physics
Volume111
Issue number9-11
DOIs
Publication statusPublished - Jul 1 2013

Fingerprint

Fluorobenzenes
Fluorination
fluorination
Halogenation
Benzene
benzene
Bond length
rings
Substitution reactions
Fluorine
estimates
Vibration
Least-Squares Analysis
Electron diffraction
Ground state
Electronic structure
Spectrum Analysis
Carbon
Gases
Electrons

Keywords

  • ab initio
  • equilibrium structures
  • fluorobenzene
  • ring distortions
  • semiexperimental structure
  • spectroscopic constants
  • structural refinement

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Condensed Matter Physics
  • Biophysics
  • Molecular Biology

Cite this

Deformation of the benzene ring upon fluorination : Equilibrium structures of all fluorobenzenes. / Demaison, Jean; Rudolph, Heinz Dieter; Császár, A.

In: Molecular Physics, Vol. 111, No. 9-11, 01.07.2013, p. 1539-1562.

Research output: Contribution to journalArticle

Demaison, Jean ; Rudolph, Heinz Dieter ; Császár, A. / Deformation of the benzene ring upon fluorination : Equilibrium structures of all fluorobenzenes. In: Molecular Physics. 2013 ; Vol. 111, No. 9-11. pp. 1539-1562.
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