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Hydrogen Bonding and Dynamic Behaviour in Crystals and Polymorphs of Dicarboxylic–Diamine Adducts: A Comparison between NMR Parameters and X‐ray Diffraction Studies
Author(s) -
Gobetto Roberto,
Nervi Carlo,
Chierotti Michele R.,
Braga Dario,
Maini Lucia,
Grepioni Fabrizia,
Harris Robin K.,
Hodgkinson Paul
Publication year - 2005
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.200500616
Subject(s) - adduct , chemistry , hydrogen bond , crystallography , malonic acid , hydrate , malonate , molecule , diamine , fumaric acid , hydrogen , polymer chemistry , organic chemistry
Fumaric, malonic, maleic, and hydromuconic (HOOCCH 2 (CH) 2 CH 2 COOH) acids were used to prepare a series of hydrogen‐bonded adducts or salts, depending on whether acid–base proton transfer takes place, with the dibase [N(μCH 2 CH 2 ) 3 N] in various stoichiometric ratios. The resulting compounds have been investigated by using the 1 H MAS, 15 N, and 13 C cross polarisation magic‐angle spinning (CPMAS) methods and discussed in relation to X‐ray diffraction studies to ascertain the nature of the O‐H ⋅⋅⋅ O, N ⋅⋅⋅ H‐O, and N + ‐H ⋅⋅⋅ O − hydrogen bonds between the various species. In addition, two polymorphic forms of the malonic compound and a hydrate in the maleic case were examined. We also present the correlations between the chemical shifts of the hydrogen‐bonded protons and those from the proton transfer reaction (acid‐to‐base) with the heavy atom distances. The dynamic behaviour in the solid‐state of the [N(μCH 2 CH 2 ) 3 N] adducts with fumaric 2:1, maleic 1:1 hydrate, and hydromuconic acids, and a malonate 2:1 polymorph adduct have been investigated by using variable‐temperature 1 H spin–lattice relaxation times. A substantial agreement between the activation energies obtained from fitting the T 1 data and the results of potential energy barrier calculations demonstrates that the facile reorientation of the [N(μCH 2 CH 2 ) 3 N] molecule occurs in several of the adducts.