Synthesis, structure, and reactivity of organochalcogen (Se, Te) compounds derived from 1-(N,N-dimethylamino)naphthalene and N,N-dimethylbenzylamine

A series of intramolecularly coordinated organochalcogen compounds incorporating the 8-(dimethylamino)-1-naphthyl and 2-[(dimethylamino)methyl]phenyl groups has been synthesized. All the compounds were synthesized using the ortholithiation methodology. Insertion of elemental selenium into the Li-C bond of RLi (6) (R = 8-(dimethylamino)-1-naphthyl) afforded the lithium areneselenolate RSeLi (7). Oxidative workup of 7 yielded the yellow diselenide 8 in good yield. Reaction of 8 with a stoichiometric amount of sulfuryl chloride gave the monochloro derivative (9). Controlled bromination of diselenide (8) with bromine in carbon tetrachloride gave the stable selenenyl bromide (10). Compound 8 underwent facile reaction with a stoichiometric amount of iodine to give the corresponding novel monoiodo compound (11) in which selenium is covalently bonded to iodine. Attempts to synthesize the chalcogenides, R2E, 12 (E = Se) and 13 (E = Te), by the reaction of 6 with Se(dtc)(2) and Te(dtc)(2) (dtc = diethyldithiacarbamate), respectively, were unsuccessful. The reaction of 6 with Te(dtc)(2) afforded the stable RTe(dtc) (14) instead of the expected telluride R2Te (13). In contrast, the reaction of R'Li (17) (R' = 2-[(dimethylamino)methyl)phenyl] with Se(dtc)(2) and Te(dtc)(2) afforded the expected selenide R'Se-2 (18) and telluride R'Te-2 (19), respectively, in moderate yields. The compounds were characterized by elemental analysis, NMR (H-1, C-13, Se-77, Te-125), and mass spectral techniques. The structures of the compounds 9, 11, 14, and 18 were determined by X-ray crystallography. Although N ... E (E = Se or Te) nonbonded interactions are present in the solid state in all the derivatives, in solution the pyramidal inversion at the nitrogen center is not blocked, and as a result, the NMe2 signals are observed as sharp signals in the H-1 NMR spectra.