Abstract
The supramolecular structure of N -(6-bromocyclohex-3-en-1-yl)- and N -(7-bromobicyclo[2.2.1]hept-2-yl) N ′-(triflyl)ethanimidamide was analyzed according to XRD and IR spectroscopy in various states in a wide temperature range and quantum chemical calculations. The supramolecular structure of the studied amidines is based on linear dimers of the E-syn -conformer with N-H∙∙∙O=S hydrogen bonds, which form polymer chains. The layered structure of N -(6-bromocyclohex-3-en-1-yl)- N ′-(triflyl)ethanimidamide is formed by C-H∙∙∙O, C-H∙∙∙Br, and C-H∙∙∙F contacts, and in the case of N -(7-bromobicyclo[2.2.1]hept-2-yl)- N ′-(triflyl)ethanimidamide by C-H∙∙∙O contacts. The molecular electrostatic potential maps of the studied amidines were obtained and their correspondence between the strengths of H-bonds and shortened contacts in both compounds was shown. Comparison of experimental and calculated frequencies ν(NH) in monomers and dimers of N -(6bromocyclohex-3-en-1-yl)- N ′-(triflyl)ethanimidamide showed the presence of conformational E-syn → E-anti transitions with the formation of cyclic dimers, the proportion of which increases with decreasing temperature.