Intermolecular interactions of proton transfer compounds: synthesis, crystal structure and Hirshfeld surface analysis
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Date
2010-06-10
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Abstract
Three new proton transfer compounds, [2-ammonio-5-methylcarboxybenzene
perchlorate (1), (C8H10NO2+ClO4 ), 4-(ammoniomethyl)carboxybenzene nitrate
(2), (C8H10NO2+NO3 ), and 4-(ammoniomethyl)carboxybenzene perchlorate
(3), (C8H10NO2+ClO4 )], have been synthesized, their IR modes of vibrations
have been assigned and their crystal structures studied by means of singlecrystal X-ray diffraction. Their asymmetric units consist of one cation and one
anion for both compounds (1) and (2). However, the crystal structure of
compound (3) is based on a pair of cations and a pair of anions in its asymmetric
unit. The three-dimensional Hirshfeld surface analysis and the two-dimensional
fingerprint maps revealed that the three structures are dominated by H O/
O H and H H contacts. The strongest hydrogen-bonding interactions are
associated with O—H O and N—H O constituting the highest fraction of
approximately 50%, followed by those of the H H type contributing 20%.
Other close contacts are also present, including weak C H/H C contacts
(with about 10%)