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A supramolecular network of 2‐(4,4,5,5‐tetramethyl‐3‐oxylimidazoline‐1‐oxide)‐5‐bromopyridine built through π – π stacking and hydrogen bonding interactions
Author(s) -
Rajadurai Chandrasekar,
Fuhr Olaf,
Enkelmann Volker,
Baumgarten Martin
Publication year - 2006
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.1032
Subject(s) - stacking , chemistry , supramolecular chemistry , crystallography , antiferromagnetism , hydrogen bond , pyridine , molecule , covalent bond , crystal structure , condensed matter physics , physics , organic chemistry , medicinal chemistry
The X‐ray study of 2‐(4,4,5,5‐tetramethyl‐3‐oxylimidazoline‐1‐oxide)‐5‐bromopyridine ( PyNN ) shows an unusual 3‐D supramolecular assembly formed by the combined non‐covalent interactions of π – π stacking and H‐bonding forces. The mean π – π stacking distance between two pyridine units is ∼3.64 Å. The angle between the plane of the pyridine ring and the stack column axis ( c ‐axis) is 7.46°. The H‐bonding distance between the oxygen atom of the water and the nitronyl nitroxide (NN) oxygen [H···ON] is 1.891 Å. Two potential short NO···ON contacts are found (NO1···O1N = 3.673 Å and NO1···O2N = 3.695 Å) along the stacked column. Four water molecules through H‐bonding with four different radical oxygens form a perfect square in the a , b plane which extends as a tubular cage along the stack axis. Experimental spin densities of PyNN estimated from the 1 H‐NMR spectroscopy and its bulk magnetic property have been correlated with the X‐ray structure in an attempt to understand the possible magnetic exchange interactions. The observed low temperature antiferromagnetic interaction is analyzed on the basis of McConnell's model I ( spin polarization approach ) and this magnetic behavior is probably due to the dominant NO···ON close contacts along the chain surpassing the stacking, H‐bonding and other interactions. Copyright © 2006 John Wiley & Sons, Ltd.