title: Cooperative and anticooperative effects in resonance assisted hydrogen bonds in merged structures of malondialdehyde.
abstract: We analyzed non-additive effects in resonance assisted hydrogen bonds (RAHBs) in different β-enolones, which are archetypal compounds of these types of interactions. For this purpose, we used (i) potential energy curves to compute the formation energy, ΔE, of the RAHBs of interest in different circumstances along with (ii) tools offered by quantum chemical topology, namely, the Quantum Theory of Atoms In Molecules (QTAIM) and the Interacting Quantum Atoms (IQA) electronic energy partition. We established the effect that a given H-bond exerts over ΔE associated with another RAHB, determining in this way the cooperativity or the anticooperativity of these interactions. The mesomeric structures and the QTAIM delocalisation indices are consistent with the determined cooperative or anticooperative character of two given RAHBs. The HB cooperativity and anticooperativity studied herein are directly reflected in the IQA interaction energy E, but they are modulated by the surrounding hydrocarbon chain. The IQA decomposition of ΔEcoop, a measure of the cooperativity between a pair of interacting RAHBs, indicates that the analyzed H-bond cooperative/anticooperative effects are associated with greater/smaller (i) strengthening of the pseudo-bicyclic structure of the compounds of interest and (ii) electron localisations with its corresponding changes in the intra and intermolecular exchange-correlation contributions to ΔE. Overall, we expect that this investigation will provide valuable insights into the interplay among hydrogen bonded atoms and the π system in RAHBs contributing in this way to the understanding of the general features of H-bonds.
authors.affiliation: Institute of Chemistry, National Autonomous University of Mexico, Circuito Exterior, Ciudad Universitaria, Delegación Coyoacán C.P. 04510, Mexico City, Mexico. tomasrocharinza@gmail.com.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Romero-Montalvo
authors.affiliation: Department of Analytical and Physical Chemistry, University of Oviedo, E-33006, Oviedo, Spain.
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Guevara-Vela
authors.affiliation: Department of Analytical and Physical Chemistry, University of Oviedo, E-33006, Oviedo, Spain.
authors.forename: Aurora
authors.initials: A
authors.lastname: Costales
authors.affiliation: Department of Analytical and Physical Chemistry, University of Oviedo, E-33006, Oviedo, Spain.
authors.forename: Ángel Martín
authors.initials: ÁM
authors.lastname: Pendás
authors.affiliation: Institute of Chemistry, National Autonomous University of Mexico, Circuito Exterior, Ciudad Universitaria, Delegación Coyoacán C.P. 04510, Mexico City, Mexico. tomasrocharinza@gmail.com.
authors.forename: Tomás
authors.identifier: http://orcid.org/0000-0003-1650-4150
authors.initials: T
authors.lastname: Rocha-Rinza