title: Solid state structure and solution thermodynamics of three-centered hydrogen bonds (O∙∙∙H∙∙∙O) using N-(2-benzoyl-phenyl) oxalyl derivatives as model compounds.
abstract: Intramolecular hydrogen bond (HB) formation was analyzed in the model compounds N-(2-benzoylphenyl)acetamide, N-(2-benzoylphenyl)oxalamate and N1,N2-bis(2-benzoylphenyl)oxalamide. The formation of three-center hydrogen bonds in oxalyl derivatives was demonstrated in the solid state by the X-ray diffraction analysis of the geometric parameters associated with the molecular structures. The solvent effect on the chemical shift of H6 [δH6(DMSO-d6)-δH6(CDCl3)] and Δδ(ΝΗ)/ΔT measurements, in DMSO-d6 as solvent, have been used to establish the energetics associated with intramolecular hydrogen bonding. Two center intramolecular HB is not allowed in N-(2-benzoylphenyl)acetamide either in the solid state or in DMSO-d6 solution because of the unfavorable steric effects of the o-benzoyl group. The estimated ΔHº and ΔSº values for the hydrogen bonding disruption by DMSO-d6 of 28.3(0.1) kJ·mol-1 and 69.1(0.4) J·mol-1·K-1 for oxalamide, are in agreement with intramolecular three-center hydrogen bonding in solution. In the solid, the benzoyl group contributes to develop 1-D and 2-D crystal networks, through C-H∙∙∙A (A = O, π) and dipolar C=O∙∙∙A (A = CO, π) interactions, in oxalyl derivatives. To the best of our knowledge, this is the first example where three-center hydrogen bond is claimed to overcome steric constraints.
authors.affiliation: Departamento de Ciencias Básicas, Unidad Profesional Interdisciplinaria de Biotecnología del Instituto Politécnico Nacional, Av. Acueducto s/n Barrio la Laguna Ticomán, México D.F. 07340, Mexico. carloszepgc@gmail.com.
authors.forename: Carlos Z
authors.initials: CZ
authors.lastname: Gómez-Castro
authors.affiliation: Departamento de Ciencias Básicas, Unidad Profesional Interdisciplinaria de Biotecnología del Instituto Politécnico Nacional, Av. Acueducto s/n Barrio la Laguna Ticomán, México D.F. 07340, Mexico. ipadillamar@ipn.mx.
authors.forename: Itzia I
authors.initials: II
authors.lastname: Padilla-Martínez
authors.affiliation: Departamento de Ciencias Básicas, Unidad Profesional Interdisciplinaria de Biotecnología del Instituto Politécnico Nacional, Av. Acueducto s/n Barrio la Laguna Ticomán, México D.F. 07340, Mexico. efren1003@yahoo.com.mx.
authors.forename: Efrén V
authors.initials: EV
authors.lastname: García-Báez
authors.affiliation: Departamento de Ciencias Básicas, Unidad Profesional Interdisciplinaria de Biotecnología del Instituto Politécnico Nacional, Av. Acueducto s/n Barrio la Laguna Ticomán, México D.F. 07340, Mexico. j_luis666@msn.com.
authors.forename: José L
authors.initials: JL
authors.lastname: Castrejón-Flores
authors.affiliation: Laboratorio de Posgrado, Facultad de Ciencias Químicas, Universidad de Colima, Km 9 Carretera Colima-Coquimatlán, Colima 28400, Mexico. peraza@ucol.mx.
authors.forename: Ana L
authors.initials: AL
authors.lastname: Peraza-Campos
authors.affiliation: Laboratorio de Posgrado, Facultad de Ciencias Químicas, Universidad de Colima, Km 9 Carretera Colima-Coquimatlán, Colima 28400, Mexico. fjmartin@ucol.mx.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Martínez-Martínez
mesh_terms: D018360:Crystallography, X-Ray; D006859:Hydrogen / Q000737:chemistry*; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010649:Phenylalanine / Q000031:analogs & derivatives / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D013816:Thermodynamics; D014961:X-Ray Diffraction
chemical_list: D012996:Solutions; D012997:Solvents; D010649:Phenylalanine; D006859:Hydrogen