INTRAMOLECULARLY COORDINATED LOW-VALENT ORGANOTELLURIUM COMPLEXES DERIVED FROM 1-(DIMETHYLAMINO) NAPHTHALENE

A series of low-valent intramolecularly coordinated organotellurium co mpounds incorporating the 8-(dimethylamino)-1-naphthyl group has been synthesized by the organolithium route. Insertion of elemental telluri um into the Li-C bond of RLi (2) affords the tellurolate RTeLi (3) (R = 8-(dimethylamino)-1-naphthyl). Oxidative workup of 3 gives dark red ditelluride 4 in moderate yield. Reaction of 2 with ''PhTeBr'' afforde d telluride 5. Interestingly, the reaction of 2 with TeI2 afforded the stable tellurenyl iodide 6 instead of the expected telluride R(2)Te. Controlled bromination of ditelluride with bromine in chloroform gave stable tellurenyl bromide 7 whereas bromination with excess bromine le ads to the isolation of tellurium(IV) tribromide 8. Ditelluride 4 was found to be inert to the reactions with diazomethane and reducing agen ts like NaBH4, NaH, and LiAIH(4). The compounds were characterized by elemental analysis, NMR (H-1, C-13, Te-125), and mass spectroscopic te chniques. For three of these compounds R(2)Te(2) (4), RTePh (5), and R TeBr (7) the molecular structures in the solid state have been determi ned by X-ray diffraction studies. All the three complexes which have b een structurally characterized have a T-shaped geometry around the cen tral tellurium atom. Though there are weak Te ... N interactions in th e solid state, in solution pyramidal inversion at the N-center is not blocked and as a result, the NMe(2) signals are observed as sharp sing lets in the H-1 NMR spectra.