Affiliations: [a] Young Researchers and Elite Club, Yadegar-e-Imam Khomeini (RAH) Branch, Islamic Azad University, Tehran, Iran | [b] Department of Chemistry, Amirkabir University of Technology, Tehran, Iran | [c] Department of Chemistry, College of Basic Science, Yadegar-e-Imam Khomeini (RAH) Branch, Islamic Azad University, Tehran, Iran
Correspondence:
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Corresponding author: Marzieh Sohrabi, Young Researchers and Elite Club,
Yadegar-e-Imam Khomeini (RAH) Branch, Islamic Azad University, Tehran, Iran. Tel.: +98 2177934425; Fax: +98 2177934425. [email protected]
Abstract: The dihydrogen bonding (DHB) interactions were studied theoretically between the hydrogen atoms of BeH2 (1) and MgH2 (2) with those of HC≡CX where X = H (3), CH3 (4), F (5), Cl (6) to form the complexes H-Be-H ... HC≡CX (7–10) and H-Mg-H …HC≡CX (11–14), respectively. The structures of compounds 1–14 were optimized at MP2 method using 6-311++G(d,p) basis set. The most negative binding energy was measured for structure 4 among isolated analogues 3–6. The complexes 9 and 14 indicated the most negative BSSE corrected ΔEdihydrogen bonding values among BeH2 and MgH2 dihydrogen bonded compounds, respectively. A linear relationship was obtained between the H …H distance and (ΔEdihydrogen bonding + BSSE) values in which the energy increases with lengthening the H …H distance. All of the ΔGinteraction and ΔG#interaction were positive confirming the DHB interactions for all complexes at both transition state and final optimized forms are endergonic indicating they are non-spontaneous interactions. The smaller band gaps of complexes 7–14 compared to those of their related isolated acetylene derivatives 3–6 reveals the increase in electrical conductivities upon formation of dihydrogen bonds. The QTAIM computations supported the covalent/shared character of the C–H, C≡C, C-Cl bonds, the intermediate character of Be-H, Mg-H, C-F bonds while the electrostatic nature of H ... H interactions.
Keywords: Dihydrogen bonding, MP2 method, QTAIM, band gap, BSSE
