title: Effect of electronic interactions on NMR 1J(CF) and 2J(CF) couplings in cis- and trans-4-t-butyl-2-fluorocyclohexanones and their alcohol derivatives.
abstract: In order to study the influence of hyperconjugative, inductive, steric, and hydrogen-bond interactions on (1)J(CF) and (2)J(CF) NMR spin-spin coupling constants (SSCCs), they were measured in cis- and trans-4-t-butyl-2-fluorocyclohexanones and their alcohol derivatives. The four isotropic terms of those SSCCs, Fermi contact (FC), spin dipolar (SD), paramagnetic spin-orbit (PSO), and diamagnetic spin-orbit (DSO), were calculated at the SOPPA(CCSD)/EPR-III level. Significant changes in FC and PSO terms along that series of compounds were rationalized in terms of their transmission mechanisms by employing a qualitative analysis of their expressions in terms of the polarization propagator formalism. The PSO term is found to be sensitive to proximate interactions like steric compression and hydrogen bonding; we describe how it could be used to gauge such interactions. The FC term of (2)J(CF) SSCC in cis-4-t-butyl-2-fluorocyclohexanone is rationalized as transmitted in part by the superposition of the F and O electronic clouds.
authors.affiliation: Chemistry Institute, University of Campinas, Post Office Box 6154, 13084-971 Campinas, SP, Brazil.
authors.forename: Pedro R
authors.initials: PR
authors.lastname: Anizelli
authors.forename: Denize C
authors.initials: DC
authors.lastname: Favaro
authors.forename: Rubén H
authors.initials: RH
authors.lastname: Contreras
authors.forename: Cláudio F
authors.initials: CF
authors.lastname: Tormena
mesh_terms: D000438:Alcohols / Q000737:chemistry*; D003512:Cyclohexanones / Q000138:chemical synthesis / Q000737:chemistry*; D004583:Electrons; D009682:Magnetic Resonance Spectroscopy / Q000592:standards; D015394:Molecular Structure; D011789:Quantum Theory; D012015:Reference Standards; D013237:Stereoisomerism
chemical_list: C560951:4-tert-butyl-2-fluorocyclohexanone; D000438:Alcohols; D003512:Cyclohexanones