Original scientific paper

Structure and Hydrogen Bonding Interactions in Methoxysalicylaldehyde Thiosemicarbazone Derivatives in Solution by NMR and DFT Methods

Predrag Novak ; Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, HR-10000 Zagreb, Croatia
Katarina Pičuljan ; Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, HR-10000 Zagreb, Croatia
Tomica Hrenar ; Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, HR-10000 Zagreb, Croatia
Vilko Smrečki ; NMR Center, Ruđer Bošković Institute, Bijenička cesta 54, HR-10000 Zagreb, Croatia

Abstract

Solution state structure and hydrogen bonding in 4- and 5-methoxysalicylaldehyde 4-phenyl-thiosemicarbazones, 1 and 2, have been studied by a combined use of NMR spectroscopy and DFT calculations. It has been shown that both compounds existed in hydroxy-thione tautomeric form in solution as previously found in solid state. Two kinds of hydrogen bonds were found to exist in solution, i.e. intra- and inter-molecular. DFT calculations and chemical shift values support the conclusion that three center hydrogen bonds were formed between the studied compounds and the solvent used, involving OH and NH groups. The solution state structures of 1 and 2 were found to differ slightly from those observed in the solid state which was attributed to a low barrier of rotation around the N–N bond

Keywords

salicylaldehyde 4-phenylthiosemicarbazones; NMR; DFT; hydrogen bonds

Hrčak ID:

39695

URI

https://hrcak.srce.hr/39695

Publication date:

15.7.2009.

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