Synthesis and multinuclear NMR investigation of some mesoionic 3-phenyl-5-imino-1,2,3,4-oxatriazole imines
作者:Jarosław Jaźwiński、Olga Staszewska-Krajewska
DOI:10.1016/j.molstruc.2003.08.017
日期:2004.1
Six new derivatives of mesoionic 3-phenyl-5-imino-1,2,3,4-oxatriazole imine have been obtained and investigated by H-1, C-13, N-14, N-15 and O-17 NMR techniques. The N-15 and O-17 NMR studies reveal that mesoionic oxatriazoles imines exist in a cyclic, 'mesoionic' form. Two stable conformers of mesoionic 3-phenyl-5-imino-1,2,3,4-oxatriazole imines, E and Z, in comparable concentrations, have been detected for the first time in the solution by the use of low temperature NMR experiments. 1H NMR techniques and band shape analysis were applied for estimation of Z-E interconversion barrier of mesoionic 3-phenyl-5-methylimino-1,2,3,4-oxatriazole imine 6 and 3-phenyl-5-benzylimino-1,2,3,4-oxatriazole imine 10. Some one-bond (1)J(N-15-C-13) coupling constants have been measured using N-15 enriched oxatriazole and tetrazole, as a means of the C5-N(-)6 bond characterisation. (C) 2003 Elsevier B.V. All rights reserved.