Conformational analysis of 2-halocyclopentanones by NMR and IR spectroscopies and theoretical calculations

Autor(es)

Martins, Carina R. ^[1] ; Ducati, Lucas C. ^[1] ; Tormena, Claudio F. ^[1] ; Rittner, Roberto ^[1]

Afiliação do(s) autor(es)

^[1] State Univ Campinus, Inst Chem, Phys Organ Chem Lab, BR-13084971 Campinas, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY; v. 72, n. 5, p. 1089-1096, JUN 2009.
• Citações Web of Science: 5

Resumo

The conformational isomerism of 2-chlorocyclopentanone and 2-bromocyclopentanone has been determined through the solvent dependence of the (1)H NMR (3)J(HH) coupling constants, theoretical calculations and infrared data, using the solvation theory for the treatment of NMR data. In 2-chlorocyclopentanone, the energy difference (E(psi-r) - E(psi-a)), in the isolated molecule at B3LYP level of theory, between the pseudo-equatorial (psi-e) and pseudo-axial (psi-a) conformers is 0.42 kcal mol(-1), which decreases ill CCl(4) and in acetonitrile Solutions. in good agreement with infrared data (vc=o), despite the uncertainties of the latter method. The conformational equilibrium for 2-bromocyclopentanone is also between the psi-e and psi-a conformations, with an energy difference (E(psi-p) - E(psi-a)), in the isolated molecule at B3LYP level of theory, is 0.85 kcal mol(-1) which decreases in CCl(4) and in acetonitrile Solutions, also in good agreement with infrared data. (C) 2009 Elsevier B,V. All rights reserved. (AU)

• Processo FAPESP: 05/59649-0 - Estudos de estrutura eletrônica e molecular através de métodos espectroscópicos e cálculos teóricos
• Beneficiário: Roberto Rittner Neto
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 06/02783-9 - Desenvolvimento de funções de base para cálculo teórico de acoplamentos J(P,P), J(P,C) e J(P,H)
• Beneficiário: Lucas Colucci Ducati
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 06/03980-2 - Interacoes de orbitais e seus efeitos nas constantes de acoplamento escalar em rmn: estudo experimental e teorico.
• Beneficiário: Claudio Francisco Tormena
• Modalidade de apoio: Auxílio à Pesquisa - Regular