JChemPhys_127_144314.pdf (626.17 kB)
Coordination structures of lithium-methylamine clusters from infrared spectroscopy and ab initio calculations.
journal contributionposted on 2013-06-26, 13:13 authored by Tom E. Salter, Andrew M. Ellis
Spectra of clusters formed between lithium atoms and methylamine molecules are reported for the first time. Mass-selective infrared spectra of Li(NH(2)CH(3))(n) have been recorded in both the N-H and C-H stretching fundamental regions. The infrared spectra are broadly in agreement with ab initio predictions, showing redshifted N-H stretching bands relative to free methylamine and a strong enhancement of the N-H stretching fundamentals relative to the C-H stretching fundamentals. The ab initio calculations suggest that, for n=3, the methylamine molecules bunch together on one side of the lithium atom to minimize repulsive interactions with the unpaired electron density. The addition of a fourth methylamine molecule results in closure of the inner solvation shell and, thus, Li(NH(2)CH(3))(5) is forced to adopt a two-shell coordination structure. This is consistent with neutron diffraction studies of concentrated lithium/methylamine solutions, which also suggest that the first solvation shell around the lithium atom can contain a maximum of four methylamine molecules.
CitationJournal of Chemical Physics, 2007, 127 (14), 4314.
Author affiliation/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Chemistry
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