Structural Organization of Symmetrical Dialkylthiuram Disulfides and Their Cyclic Analogs: X-Ray Diffraction and CP/MAS (13C, 15N) NMR Studies

High-resolution 13C and 15N solid-state NMR spectra were recorded for seven crystalline tetraalkyl-thiuram disulfides and their cyclic analogs of the general formula [R2NC(S)S]2 (where R = CH3, C2H5, C3H7, and i-C3H7 or R2 = (CH2)5, (CH2)6, and (CH2)4O). The 15N and 13C NMR resonances were assigned to the particular atoms in the compounds studied. Different isotropic 15N chemical shifts for both dialkyldithiocarbamato groups were interpreted while considering the inductive effects of the alkyl substituents combined with the mesomeric effect of the dithiocarbamato group. X-ray diffraction data were used to refine the molecular structure of bis(cyclohexamethylene)thiuram disulfide and to quantitatively characterize the conformations of the seven-membered N(CH2)6 heterocycles.