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Spectroscopic and Theoretical Studies on Solid 1,2‐Ethylenediamine Dihydrochloride Salt
Author(s) -
Amado Ana M.,
Otero Juan Carlos,
Marques M. Paula M.,
Batista de Carvalho Luís A. E.
Publication year - 2004
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200400350
Subject(s) - ethylenediamine , chemistry , counterion , diamine , ab initio , raman spectroscopy , amine gas treating , salt (chemistry) , molecule , chloride , infrared spectroscopy , ion , computational chemistry , crystallography , inorganic chemistry , organic chemistry , physics , optics
A structural study of [H 3 N(CH 2 ) 2 NH 3 )] 2+ ⋅2Cl − , the smallest element of the homologous series of the α , ω ‐diamine dihydrochlorides, was carried out by means of Raman and FTIR spectroscopy coupled to ab initio molecular orbital (MO) calculations. As a primary concern, an adequate molecular model for the representation of these solid amine salts was chosen. Thus, several models, varying in the number and position of the counterions as well as in the number of diamine units, were considered. It was found that the best molecular system (i.e., that yielding the best compromise between accuracy and computational requirements) consists of one ethylenediamine cation surrounded by six chloride ions in an arrangement based on the crystal structure reported in the literature for [H 3 N(CH 2 ) 2 NH 3 )] 2+ ⋅2Cl − . This conclusion will hopefully allow for a better understanding of the conformational preferences, in the solid state, of these biologically relevant linear polyamines.