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1 H, 13 C and 15 N NMR study of N 1 ‐alkyl‐ N 2 ‐arylthioureas
Author(s) -
Wawer Iwona,
Koleva Vera
Publication year - 1993
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260310413
Subject(s) - chemistry , alkyl , chemical shift , nmr spectra database , carbon 13 nmr , nuclear magnetic resonance spectroscopy , crystallography , stereochemistry , spectral line , organic chemistry , physics , astronomy
13 C and 15 N NMR chemical shifts were measured for N 1 ‐alkyl‐ N 2 ‐arylthioureas. The absence of decoalescence of the N 1 ‐alkyl group carbon signals down to 190 K, the europium‐induced chemical shifts and the molecular mechanics calculations indicate that the preferred conformation is E , Z . Solvent effects suggest that N 1 ‐alkyl‐ N 2 arylthioureas exist as dimers, forming an eight‐membered ring hydrogen bonded complex. In N 1 , N 1 ‐dimethyl‐ N 2 ‐phenylthiourea the barrier to rotation around the CN 1 bond is 47 kJ mol −1 (from 13 C NMR, in CD 2 Cl 2 ). The upfield N 1 ‐CH 3 signal in both the 1 H and 13 C NMR spectra results from the methyl group anti to the CS and the low‐field signal from the syn methyl group.