Experimental and theoretical studies on mono-iodohistamine

The structure of mono-iodohistamine cation was determined by the H-1, C-13 NMR, supported by ab initio calculations. Theoretical NMR spectra of the tw o mono-iodohistamine tautomers were calculated by using the CHF-GIAO approa ch. The N3-H tautomer of 4-I-histamine cationic form has been predicted to be the most stable, and its potential energy surface has been scanned at th e HF/3-21G(**) level. Reasons for higher stability of the 4-I-histamine com paring to the other iodohistamine isomers are also discussed. (C) 2001 Else vier Science B.V. All rights reserved.