Telluration of seleno- and chloroiminium salts leading to various telluroamides, and their structure and NMR properties

The reaction of seleno- and chloroiminium salts with a tellurating agent derived from LiAlH4 and elemental tellurium gave telluroamides in moderate to good yields. This new synthetic method enabled the isolation of the first aliphatic and secondary telluroamides. The molecular structure of an aromatic telluroamide was successfully revealed for the first time; the length of the Cdouble bond; length as m-dashTe bond in the aromatic telluroamide was the same as that in the telluroformamide–Cr complex, and the aromatic ring and Tedouble bond; length as m-dashC–N moiety were not planar. Unlike the structure in the solid state, spectroscopic data of telluroamides suggest that there is conjugation between these two planes. The properties of the NMR spectra of a series of chalcogenoamides are also discussed.