ISSN:
1434-4475
Keywords:
Keywords. Schiff bases; Crystal structure; Proton delocalization; Short hydrogen bonds; FT-IR spectra.
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Description / Table of Contents:
Zusammenfassung. Drei ortho-hydroxy-substituierte Schiffsche Basen (2-(Methylimino-phenyl-methyl)-phenol (1), 4-Methyl-2-(methylimino-phenyl-methyl)-phenol (2), 2-(Benzylimino-phenyl-methyl)-phenol (3)) wurden synthesiert, in welchen das Wasserstoffatom der C*C(H)*N-Gruppe durch einen Phenylring substituiert ist. Es wurden starke Wasserstoffbrückenbindungen vom Typ O*H⋯N (d ON=2.496(2) Å, d OH=1.11(3) Å, d HN=1.45(4) Å und d ON=2.488(2) Å, d OH=1.20(4) Å, d HN=1.37(4) Å in 1; d ON=2.505(2) Å, d OH=1.16(3) Å, d HN=1.39(3) Å in 2; d ON=2.528(2) Å, d OH=1.08(3) Å, d HN=1.54(4) Å in 3) gefunden, wobei vor allem in 1 und 2 eine beträchtliche Delokalisierung des Protons auftritt. Es konnte gezeigt werden, daß die Stärkung der Wasserstoffbrückenbindung im Vergleich zu nichtsubstituierten Verbindungen aus der sterischen Abstoßung des Phenylrings resultiert.
Notes:
Summary. Three ortho-hydroxy Schiff bases (2-(methylimino-phenyl-methyl)-phenol (1), 4-methyl-2-(methylimino-phenyl-methyl)-phenol (2), 2-(benzylimino-phenyl-methyl)-phenol (3)) were synthesized in which the hydrogen atom in the C*C(H)*N group was substituted by a phenyl ring. Their crystal structures were determined. Strong O*H⋯N type intramolecular hydrogen bonds were found (d ON=2.496(2) Å, d OH=1.11(3) Å, d HN=1.45(4) Å and d ON=2.488(2) Å, d OH= 1.20(4) Å, d HN=1.37(4) Å in 1; d ON=2.505(2) Å, d OH=1.16(3) Å, d HN=1.39(3) Å in 2; d ON=2.528(2) Å, d OH=1.08(3) Å, d HN=1.54(4) Å in 3 together with a large proton delocalization, especially in 1 and 2. It was demonstrated that the strengthening of the hydrogen bond in comparison to related non substituted compounds results from the steric repulsion exerted by the phenyl ring.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/PL00010288
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