Premium
Nonpolar Dihydrogen Bonds—On a Gliding Scale from Weak Dihydrogen Interaction to Covalent HH in Symmetric Radical Cations [H n E‐H‐H‐EH n ] +
Author(s) -
Krapp Andreas,
Frenking Gernot,
Uggerud Einar
Publication year - 2008
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200701613
Subject(s) - chemistry , covalent bond , hydride , matrix element , crystallography , chemical bond , hydrogen bond , computational chemistry , molecule , hydrogen , physics , organic chemistry , particle physics
Abstract The electronic structures and bonding patterns for a new class of radical cations, [H n E‐H‐H‐EH n ] + (EH n =element hydride, E=element of Groups 15–18), have been investigated by applying quantum‐chemical methods. All structures investigated give rise to symmetric potential energy minimum structures. We envisage clear periodic trends. The HH bond length is shorter for elements toward the bottom of the periodic table of elements, and a short HH bond corresponds to accumulation of electron density in the central HH region. All [H n E‐H‐H‐EH n ] + of Groups 15–17 are thermodynamically unstable towards loss of either H 2 or H. The barriers for these dissociations are rather low. The Group 18 congeners, except E=Xe, appear to be global minima of the respective potential energy surfaces. The findings are discussed in terms of H 2 bond activation, and a general mechanistic scheme for the standard reduction process 2H + + 2e − → H 2 is given. Finally, it is proposed that some of the symmetric radical cations are likely to be observed in mass spectrometric or matrix isolation experiments.