Rotational barriers in ammonium hexachlorometallates as studied by NMR, tunneling spectroscopy and ab initio calculations

A. Birczynski, Z.T. Lalowicz, Zbigniew Lodziana

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Ammonium hexachlorometallates, (NH4)(2)MCl6 With M = Pd, Pt, Ir, Os, Re, Se, Sn, Te and Pb, comprise a set of compounds with systematically changing properties. The compounds may be ordered according to decreasing tunnelling frequency (TF) of ammonium ions, which is related to the increasing potential barrier. It was also observed that TF correlates directly with the lattice constant of a particular compound. This correlation is explained by density-functional theory (DFT). The size of the unit cell is governed by the nature of metal-chlorine interaction, with respect to which the studied compounds can be divided into two subgroups. The group containing d-metals (Pd, Pt, Ir, Os, Re) has stronger covalent M-Cl bond and smaller unit cell. The second category contains p-elements (Se, Sn, Te, Pb), which exhibit larger ionic charges and the larger unit cell. The differences in the electronic structure explain observed variation of the tunnelling frequencies for NH4+. The theory provides also M-Cl distances and barriers for C-2 and C-3 rotations of ammonium ions in respective compounds, which show good agreement with experimental values. (C) 2004 Elsevier B.V. All rights reserved.
Original languageEnglish
JournalChemical Physics
Volume299
Issue number1
Pages (from-to)113-122
ISSN0301-0104
DOIs
Publication statusPublished - 2004

Fingerprint Dive into the research topics of 'Rotational barriers in ammonium hexachlorometallates as studied by NMR, tunneling spectroscopy and ab initio calculations'. Together they form a unique fingerprint.

Cite this