An ab initio study of hydrogen complexes of the X-H … π type between acetylene and HF or HCl

Araújo, Regiane C. M. U.; Silva, João Bosco P. da; Ramos, Mozart N.

doi:10.1016/0584-8539(94)00194-g

Cited by 69 publications

(15 citation statements)

References 23 publications

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“…Del Bene et al 8(a), 8(b) have also shown that intermolecular distances and vibrational shifts of H-bonded complexes are well described with the second-order many-body Möller-Plesset level of theory using a split-valence basis set with polarization and diffuse functions. Indeed, our calculations 1,2 with the larger 6-311++G** basis set at the MP2 level have correctly predicted the binding energy, the H-bond distance and the shift of the H-X stretching frequency of the acetylene-HX complexes with X =F, Cl, CN, NC, CCH. This level of calculation was found to be essential for an adequate description of nonspherical atomic densities and polarizability effects 10 .…”

Section: Introductionsupporting

confidence: 51%

An Ab Initio MP2 Study of HCN-HX Hydrogen Bonded Complexes

Araújo¹,

Ramos²

1998

J. Braz. Chem. Soc.

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Um estudo ab initio MP2/6-311++G** foi realizado para obter geometrias, energias de establização e propriedades vibracionais dos complexos de hidrogênio HCN-HX com X = F, Cl, NC, CN e CCH. Os resultados obtidos revelaram que: (i) os valores calculados dos comprimentos das ligações de hidrogênio estão em excelente concordância com seus valores exeperimentais; (ii) a força da ligação-H está associada com a transferência de carga intermolecular e segue a ordem: HCN-HNC ≈ HCN-HF > HCN-HCl ≈ HCN-HCN > HCN-HCCH; (iii) correção BSSE introduz uma redução média de 2.4 kJ/mol na energia de estabilização MP2/6-311++G**; (iv) as energias do ponto-zero calculadas reduzem a estabilidade destes complexos e estão em boa concordância com os valores experimentais disponíveis; (v) a frequência de estiramento da molécula livre H-X sofre, como esperado, um deslocamento para baixo no espectro após a formação da ligação de hidrogênio e quanto mais curta a distância da ligação-H menor será este deslocamento; (vi) a intensidade no infravermelho deste estiramento H-X sofre a mudança mais pronunciada após a complexação, verificando-se um aumento substancial devido ao termo de fluxo de carga; (vii) as frequências de estiramento intermolecular destes complexos HCN-HX mostram uma concordância muito boa com os seus valores experimentais; e, finalmente, (viii) Os resultados obtidos para HCN-HX seguem o mesmo perfil daqueles observados para os complexos do tipo acetileno-HX. Entretanto, nestes últimos, as mudanças nas propriedades moleculares de suas moléculas livres, após a complexação, são menos pronunciadas do que aquelas observadas para os complexos HCN-HX.An ab initio MP2/6-311++G** study has been performed to obtain geometries, binding energies and vibrational properties of HCN-HX H-bonded complexes with X = F, Cl, NC, CN and CCH. These MP2/6-311++G** results have revealed that: (i) the calculated H-bond lengths are in very good agreement with the experimental ones; (ii) the H-bond strength is associated with the intermolecular charge transfer and follows the order: HCN-HNC ≈ HCN-HF > HCN-HCl ≈ HCN-HCN > HCN-HCCH; (iii) BSSE correction introduces an average reduction of 2.4 kJ/mol on the MP2/6-311++G** binding energies, i.e. 11% of the uncorrected binding energy; (iv) the calculated zero-point energies reduce the stability of these complexes and show a good agreement with the available experimental values; (v) the H-X stretching frequency is shifted downward upon H-bond formation. This displacement is associated with the H-bond length; (vi) The more pronounced effect on the infrared intensities occurs with the H-X stretching intensity. It is much enhanced after complexation due to the charge-flux term; (vii) the calculated intermolecular stretching frequencies are in very good agreement with the experimental ones; and, finally, (viii) the results obtained for the HCN-HX complexes follow the same profile as those found for the acetylene-HX series but, in the latter case, the effects on the properties of the free molecules due to complexati...

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Section: Introductionsupporting

confidence: 51%

An Ab Initio MP2 Study of HCN-HX Hydrogen Bonded Complexes

Araújo¹,

Ramos²

1998

J. Braz. Chem. Soc.

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“…Working on the expressions of the APT components as function of ECCF (or EOP), it is possible to extract local charge parameters and in particular to obtain the set of the atomic charges. 1 This task was accomplished in the past for a selected number of molecules and atoms [25,32,35], and it allowed a good description of several intra-and intermolecular chemical/physical properties [25,32,35,[47][48][49][50][51][52][53]. Anyway, severe limitations (such as the intrinsic difficulties related to absolute intensity determination, the presence of several overlapping bands, and the need of a good force field for the calculation of vibrational eigenvectors) hinder the direct determination of APT (or ðoM =oR k Þ 0 ) and thus of ECCF from experimental IR intensities.…”

Section: Model and Theorymentioning

confidence: 99%

Atomic charges from IR intensity parameters: theory, implementation and application

2012

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A computational method to extract atomic charges (IR charges) from DFT/ab initio-computed atomic polar tensors is presented and compared with commonly available population schemes. The procedure adopted and its implementation in a (freely available) code are also reported and commented. Thanks to the procedure developed, infrared charges can be now readily gathered also by non-experts, provided that Cartesian dipole derivatives from a quantum chemical calculation of the IR spectrum are available. The method has been applied for the calculation of IR charges of about 50 molecules: It performs well in describing peculiar intramolecular interactions, providing a picture of the molecular charge distribution coherent with the chemical intuition. A nice agreement is also found with charges obtained from Hirshfeld algorithm and from the fitting of the electrostatic potential (CHELPG and MK schemes). On this basis, we propose IR charges as a reliable, physically sound and easily accessible alternative to other charge parameters currently adopted.

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“…In general, although a weak or medium-strength interaction, the formation of hydrogen bonds is supported chemically by the overlapping of the LUMO and HOMO frontier orbitals of the respective donor and acceptor of protons, with a dynamic charge transfer flux occurring between them [54]. Thereby, it is inappropriate to treat hydrogen bond energies without considering charge transfer measurement [55][56][57]. In the case of heterocyclic compounds [58,59], recent studies have shown that ChelpG is an efficient method for quantifying charge transfer to the proton donor upon the formation of hydrogen bonds [60].…”

Section: Methodsmentioning

confidence: 98%

Theoretical aspects of binary and ternary complexes of aziridine⋯ammonia ruled by hydrogen bond strength

Oliveira

Araújo

2011

J Mol Model

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B3LYP calculations, ChelpG atomic charges, and quantum theory of atoms in molecules (QTAIM) integrations were used to investigate the binary (1:1) and ternary (1:2) hydrogen-bonded complexes formed by aziridine (1) and ammonia (2). In a series of analysis, geometry data, electronic parameters, vibrational oscillators, and topological descriptors were used to evaluate hydrogen bond strength, and additionally to determine the more prominent molecular deformations upon the formation of C(2)H(5)N···NH(3) (1:1) and C(2)H(5)N···2NH(3) (1:2) systems. Taking a spectroscopic viewpoint, results obtained from analysis of the harmonic infrared spectrum were examined. From these, new vibrational modes and red- and blue-shifts related to the stretch frequencies of either donors or acceptors of protons were identified. Furthermore, the molecular topology of the electronic density modeled in accord with QTAIM was absolutely critical in defining bond critical points (BCP) and ring critical points (RCP) on the heterocyclic structures. Taking all the results together allowed us to identify and characterize all the N···H hydrogen bonds, as well as the strain ring of the aziridine and its stability.

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An ab initio study of hydrogen complexes of the X-H … π type between acetylene and HF or HCl

Cited by 69 publications

References 23 publications

An Ab Initio MP2 Study of HCN-HX Hydrogen Bonded Complexes

An Ab Initio MP2 Study of HCN-HX Hydrogen Bonded Complexes

Atomic charges from IR intensity parameters: theory, implementation and application

Theoretical aspects of binary and ternary complexes of aziridine⋯ammonia ruled by hydrogen bond strength

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