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Open‐Chain Dications and Betaines with Imidazolium Molecular Motifs: Synthesis and Structural Aspects
Author(s) -
Alcalde Ermitas,
Mesquida Neus,
Alemany Montserrat,
AlvarezRúa Carmen,
GarcíaGranda Santiago,
Pacheco Pedro
Publication year - 2002
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200204)2002:7<1221::aid-ejoc1221>3.0.co;2-q
Subject(s) - chemistry , dication , deprotonation , hexafluorophosphate , zwitterion , protonation , electrospray ionization , betaine , counterion , crystallography , nuclear magnetic resonance spectroscopy , mass spectrometry , crystal structure , non covalent interactions , stereochemistry , molecule , ion , hydrogen bond , ionic liquid , organic chemistry , catalysis , chromatography
The synthesis of trinuclear open‐chain prototypes gave variable yields: > 53% for dications 1·2X and 2·2X and > 80% for proton‐ionizable dications 3·2X−5·2X incorporating 1 H ‐1,2,4‐triazole moieties. Deprotonation of the latter compounds resulted in the formation of the betaine counterparts 13·X−15·X . The courses of the dequaternization reactions of compounds 4·2X and 5·2X were also studied. The structural properties of dicationic protophanes 1·2X and 2·2X , containing bis(imidazolium) motifs, were examined by 1 H and 13 C NMR spectroscopy, electrospray mass spectrometry and by single‐crystal X‐ray diffraction analysis of the dication 1b·2PF 6 . Weak noncovalent interactions between the dications and the hexafluorophosphate ions bias the protophane conformation both in solution and in the solid state. X‐ray diffraction reveals that the PF 6 − counterions are located in a channel formed by the dications ( 1b 2+ ). (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)