title: Centrosymmetric resonance-assisted intermolecular hydrogen bonding chains in the enol form of β-diketone: Crystal structure and theoretical study.
abstract: Isobenzofuran-1(3H)-ones (phtalides) are heterocycles that present a benzene ring fused to a γ-lactone functionality. This structural motif is found in several natural and synthetic compounds that present relevant biological activities. In the present investigation, the 3-(2-hydroxy-4,4-dimethyl-6-oxocyclohexen-1-yl)isobenzofuran-1(3H)-one was characterized by single-crystal X-ray analysis. In the crystal structure, there are two molecules per asymmetric unit. One of them exhibits resonance assisted hydrogen bonds (RAHBs). Semi-empirical and DFT calculations were performed to obtain electronic structure and π-delocalization parameters, in order to better understand the energy stabilization of RAHBs in the crystal packing of the studied molecule. The structural parameters showed good agreement between theoretical and experimental data. The theoretical investigation revealed that the RAHBs stabilization energy is directly related to the electronic delocalization of the enol form fragment. In addition, RAHBs significantly affected the HOMO and charge distribution around the conjugated system.
authors.affiliation: Instituto de Química, Universidade Federal de Uberlândia, 38.400-902, Uberlândia, MG, Brazil. Electronic address: eduardofranca@ufu.br.
authors.forename: Eduardo F
authors.initials: EF
authors.lastname: Franca
authors.affiliation: Instituto de Química, Universidade Federal de Uberlândia, 38.400-902, Uberlândia, MG, Brazil.
authors.forename: Silvana
authors.initials: S
authors.lastname: Guilardi
authors.affiliation: Instituto de Química, Universidade Federal de Uberlândia, 38.400-902, Uberlândia, MG, Brazil.
authors.forename: Drielly A
authors.initials: DA
authors.lastname: Paixão
authors.affiliation: Departamento de Química, Universidade Federal de Viçosa, 36.570-900, Viçosa, MG, Brazil. Electronic address: robsonr.teixeira@ufv.br.
authors.forename: Róbson R
authors.initials: RR
authors.lastname: Teixeira
authors.affiliation: Departamento de Química, Universidade Federal de Viçosa, 36.570-900, Viçosa, MG, Brazil.
authors.forename: Wagner L
authors.initials: WL
authors.lastname: Pereira
authors.affiliation: Instituto de Física de São Carlos, Universidade de São Paulo, 13560-970 São Carlos, SP, Brazil.
authors.forename: Javier A
authors.initials: JA
authors.lastname: Ellena
mesh_terms: D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D007659:Ketones / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D013816:Thermodynamics
chemical_list: D007659:Ketones
keywords: Isobenzofuranones; Phtalides; Resonance assisted hydrogen bonds (RAHBs); Semi-empirical and DFT calculations; X-ray structure