Deuterium labeled congeners of 7-chloro-5-phenyl-3(S)-methyl-1,3-dihydro-2H-1,4-benzodiazepine (8), i.e., compounds 9 and 16-18 were prepared and their lis-nmr spectra run. For computational studies compounds 9 and 16 were chosen. The results of lis measurements revealed that 16 is present in more than 97% in the boat-like conformation I (Scheme 3).