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Structure, energy, vibrational spectrum, and Bader's analysis of πH hydrogen bonds and H(-δ)H(+δ) dihydrogen bonds.
MedLine Citation:
PMID:  23138158     Owner:  NLM     Status:  Publisher    
In this paper, the intermolecular structural study asserted by the vibrational analysis in the stretch frequencies of hydrogen bonds (πH) and dihydrogen bonds (H(-δ)H(+δ)) have definitively been revisited by means of calculations carried out by Density Functional Theory (DFT) and topological parameters derived from the classic treatise of the Quantum Theory of Atoms in Molecules (QTAIM). As a matter of fact the πH hydrogen bond is formed between the hydrofluoric acid and the C[triple bond, length as m-dash]C bond of the acetylene, but the QTAIM calculations revealed a distortion in this interaction due to the formation of the ternary complex C(2)H(2)2(HF). Although the π bonds of ethylene (C(2)H(4)), propylene (C(2)H(3)(CH(3))), and t-butylene (C(2)H(2)(CH(3))(2)) are considered proton acceptors, two hydrogen-bond types-πH and CH-can be observed. Over and above the analysis of the π hydrogen bonds, theoretical arguments also were used to discuss the red-shifts in the stretch frequencies of the binary dihydrogen complexes formed by BeH(2)HX with X = F, Cl, CN, and CCH. Although a vibrational blue-shift in the stretch frequency of the H-C bond of HCF(3) due to the formation of the BeH(2)HCF(3) dihydrogen complex was obtained, unmistakable red-shifts were detected in LiHHCF(3), MgH(2)HCF(3), and NaHHCF(3). Moreover, the alkali-halogen bonds were identified in relation to the formation of the trimolecular systems NaH2(HCF(3)) and NaH2(HCCl(3)). At last, theoretical calculations and QTAIM molecular integrations were used to study a novel class of dihydrogen-bonded complexes (mC(2)H(5)(+) nMgH(2) with m = 1 or 2 and n = 1 or 2) based in the insight that MgH(2) can bind with the non-localized hydrogen H(+δ) of the ethyl cation (C(2)H(5)(+)). In an overview, QTAIM calculations were applied to evaluate the molecular topography, charge density, as well as to interpret the shifted frequencies either to red or blue caused by the formation of the hydrogen bonds and dihydrogen bonds.
Boaz Galdino de Oliveira
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-11-9
Journal Detail:
Title:  Physical chemistry chemical physics : PCCP     Volume:  -     ISSN:  1463-9084     ISO Abbreviation:  Phys Chem Chem Phys     Publication Date:  2012 Nov 
Date Detail:
Created Date:  2012-11-9     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100888160     Medline TA:  Phys Chem Chem Phys     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Institute of Environmental Sciences and Sustainable Development (ICADS), Federal University of Bahia, 47801-100, Barreiras - BA, Brazil.
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