1,3-THIAZEPINES. 6. UV SPECTROSCOPIC AND THEORETICAL STUDY OF THE ELECTRONIC STRUCTURES OF 2-AMINOTETRAHYDRO-AND 2-IMINOTETRAHYDRO-1,3-THIAZEPINES

Abstract

On the basis of studies of the electronic absorption spectra and quantum-chemical calculations of the energies and bond orders of a series of N-acetyl-N-aryl substituted 2-amino-4,5,6,7-tetrahydro-1,3-thiazepines and N-aryl substituted 2-iminohexahydro-1,3-thiazepines it has been concluded that the reason for the weak basicity of the ring nitrogen atom of the former is the acceptor properties of the amide carbonyl which obstructs the interaction of the unshared pair (USP) of this atom with the phenyl ring; in the case of the derivatives of hexahydroazepine the strengthening of the basic properties of the exocyclic nitrogen atom is associated with the conjugation of its USP with the π-electrons of the benzene ring, which is strengthening by delocalisation of the USP of the sp³-hybridized ring nitrogen atom into the azomethine bond.

How to Cite
Kristallovich, E. L.; Eshimbetov, A. G.; Ambartsumova, R. F. Chem. Heterocycl. Compd. 2003, 39, 368. [Khim. Geterotsikl. Soedin. 2003, 414.]

For this article in the English edition, see DOI https://doi.org/10.1023/A:1023927213186