Intramolecularly Coordinated Low-Valent Organotellurium Complexes Derived from 1-(Dimethylamino)naphthalene

Abstract

A series of low-valent intramolecularly coordinated organotellurium compounds incorporating the 8-(dimethylamino)-1-naphthyl group has been synthesized by the organolithium route. Insertion of elemental tellurium 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" afforded telluride 5. Interestingly, the reaction of 2 with TeI 2 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 leads to the isolation of tellurium(IV) tribromide 8. Ditelluride 4 was found to be inert to the reactions with diazomethane and reducing agents like NaBH 4 , NaH, and LiAlH 4 . The compounds were characterized by elemental analysis, NMR ( 1 H, 13 C, 125 Te), and mass spectroscopic techniques. For three of these compounds R 2 Te 2 (4), RTePh (5), and RTeBr (7) the molecular structures in the solid state have been determined by X-ray diffraction studies. All the three complexes which have been structurally characterized have a T-shaped geometry around the central tellurium atom. Though there are weak Te‚‚‚N interactions in the 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 singlets in the 1 H NMR spectra.

Synthesis and characterization of [2-(2-phenyl-5,6-dihydro-4H-1,3-oxazinyl)] tellurenyl chloride

“…The tellurenyl chloride (9) having directly bonded electron withdrawing chlorine atom shows a significant downfield shift compared with the ditelluride (8). The 125 Te NMR chemical shift for 8 is relatively more downfield shifted than those of the corresponding reported ditellurides of 1-(N,N-dimethylnaphthyl)amine (461 ppm) [3], N,N-dimethylbenzylamine (375 ppm) [4] having a sp 3 -N donor atom and (R)-4-ethyl-4-hydro-2-phenyl-2-oxazoline (424 ppm) [4], 2-phenyl-2-oxazoline (420 ppm) [4], 4,4-dimethyl-2-phenyl-2-oxazoline (417) [5] and 2-[1-(3,5-dimethylphenyl)-2-naphthyl]-4,5-dihydro-4,4-dimethyloxazole (421 ppm) [6] having a sp 2 -N donor atom. Similarly, the 125 Te NMR chemical shift of tellurenyl chloride (9) is also more downfield shifted than the tellurenyl chlorides based on the 2-[1-(3,5-dimethylphenyl)-2-naphthyl]-4,5-dihydro-4,4-dimethyloxazole (1163 ppm) [6] and 4,4-dimethyl-2-phenyl-2-oxazoline (1203 ppm) [7].…”

Synthesis and characterization of some α-naphthyl selenium/tellurium derivatives: X-ray crystal structure of benzyl-1-naphthyl selenide and diphenylmethyl-1-naphthyl selenide

“…As a result, detailed spectroscopic characterization of such compounds has scarcely been reported in the literature. Menon et al [21] have reported a number of stable low valent 1-naphthyl tellurides which incorporate dimethylamino group at C-8 position in the naphthyl ring. Intramolecular TeÁ Á ÁN coordination is found to be responsible for the greater stability of these derivatives.…”

Naphthalene and Related Systems peri‐Substituted by Group 15 and 16 Elements

“…In each compound the amine/imine nitrogen is coordinated to the tellurium atom which exhibits typical T-shaped geometry (Scheme 83). [170] Furthermore, a series of organoselenium compounds incorporating the 8-(dimethylamino)-1-naphthyl group has been synthesised, this includes stable selenenyl halides 154 (Scheme 83). [171] Very short, although varied Se···N contacts are observed in these species.…”