NMR and X-ray investigations of model tris- and bis-pyridinium fluoroborates

Spectroscopic and structural properties of two distinctly different products of the reaction of 2,4,6-trimethylpyrylium ion (and 2,4,6- triphenylpyrylium), with triple primary amine-tris(2-aminoethyl)amine (tren)—have been isolated and identified. In the case of the first moiety, one of the products is a symmetric tris-pyridinium salt, whereas the second one has only two groups reacting towards the pyridinium salt and the third group giving 3,5-xylidine derivative. For the second ion (2,4,6-triphenylpyrylium salt), we obtained only one symmetric product—trispyridinium salt. All structures have been confirmed by NMR data in solution and the structure of the asymmetric pyrydinium salt in the solid state by single crystal X-ray analysis. The structure of symmetric salt has been confirmed by 13C and 15N CPMAS NMR spectra. q 2004 Elsevier B.V. All rights reserved