title: 3-Iodobenzaldehyde: XRD, FT-IR, Raman and DFT studies.
abstract: The structure of 3-iodobenzaldehyde (3IB) was characterized by FT-IR, Raman and single-crystal X-ray diffraction techniques. The conformational isomers, optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of 3IB were examined using density functional theory (DFT) method, with the Becke-3-Lee-Yang-Parr (B3LYP) functional and the 6-311+G(3df,p) basis set for all atoms except for iodine. The LANL2DZ effective core basis set was used for iodine. Potential energy distribution (PED) analysis of normal modes was performed to identify characteristic frequencies. 3IB crystallizes in monoclinic space group P21/c with the O-trans form. There is a good agreement between the theoretically predicted structural parameters, and vibrational frequencies and those obtained experimentally. In order to understand halogen effect, 3-halogenobenzaldehyde [XC6H4CHO; X=F, Cl and Br] was also studied theoretically. The free energy difference between the isomers is small but the rotational barrier is about 8kcal/mol. An atypical behavior of fluorine affecting conformational preference is observed.
authors.affiliation: X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia; Department of Engineering Chemistry, Alva's Institute of Engineering & Technology, Mijar, Modbidri, 574225, Karnataka, India.
authors.forename: Chandraju Sadolalu Chidan
authors.initials: CSC
authors.lastname: Kumar
authors.affiliation: Department of Physics, Dumlupinar University, Kütahya 43100, Turkey.
authors.forename: Cemal
authors.initials: C
authors.lastname: Parlak
authors.affiliation: Department of Physics, Dumlupinar University, Kütahya 43100, Turkey.
authors.forename: Mahir
authors.initials: M
authors.lastname: Tursun
authors.affiliation: X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia; Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia.
authors.forename: Hoong-Kun
authors.initials: HK
authors.lastname: Fun
authors.affiliation: Computational Chemistry Group, Department of Chemistry, Faculty of Science, University of Mauritius, Réduit 80837, Mauritius.
authors.forename: Lydia
authors.initials: L
authors.lastname: Rhyman
authors.affiliation: Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia; Computational Chemistry Group, Department of Chemistry, Faculty of Science, University of Mauritius, Réduit 80837, Mauritius. Electronic address: p.ramasami@uom.ac.mu.
authors.forename: Ponnadurai
authors.initials: P
authors.lastname: Ramasami
authors.affiliation: Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia.
authors.forename: Ibrahim A
authors.initials: IA
authors.lastname: Alswaidan
authors.affiliation: Institute of Physics and Biophysics, Faculty of Science, University of South Bohemia, Branišovská 31, České Budějovice 370 05, Czech Republic.
authors.forename: Gürkan
authors.initials: G
authors.lastname: Keşan
authors.affiliation: Department of Sugar Technology and Chemistry, Sir M. Visvesvaraya PG Center, University of Mysore, Tubinakere, Mandya 571402, India.
authors.forename: Siddegowda
authors.initials: S
authors.lastname: Chandraju
authors.affiliation: X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia.
authors.forename: Ching Kheng
authors.initials: CK
authors.lastname: Quah
mesh_terms: D001547:Benzaldehydes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008968:Molecular Conformation; D011336:Probability; D011789:Quantum Theory; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D013816:Thermodynamics; D014732:Vibration; D014961:X-Ray Diffraction
chemical_list: D001547:Benzaldehydes; C032175:benzaldehyde
keywords: 3-Halogenobenzaldehyde; Crystal structure; DFT; Vibrational spectra; XRD