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Is Electronegativity a Useful Descriptor for the Pseudo‐Alkali Metal NH 4 ?
Author(s) -
Whiteside Alexander,
Xantheas Sotiris S.,
Gutowski Maciej
Publication year - 2011
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.201101949
Subject(s) - electronegativity , alkali metal , metal , chemistry , computational chemistry , inorganic chemistry , materials science , organic chemistry
Molecular ions in the form of “pseudo‐atoms” are common structural motifs in chemistry, with properties that are transferrable between different compounds. We have determined one such property—the electronegativity—for the “pseudo‐alkali metal” ammonium (NH 4 ), and evaluated its reliability as a descriptor versus the electronegativities of the alkali metals. The computed properties of ammonium’s binary complexes with astatine and of selected borohydrides confirm the similarity of NH 4 to the alkali metal atoms, although the electronegativity of NH 4 is relatively large in comparison to its cationic radius. We have paid particular attention to the molecular properties of ammonium (angular anisotropy, geometric relaxation and reactivity), which can cause deviations from the behaviour expected of a conceptual “true alkali metal” with this electronegativity. These deviations allow for the discrimination of effects associated with the molecular nature of NH 4 .