A. A. Maksimenko

Molecular and crystal structure of ortho-tellurated azomethines with intramolecular N → Te coordination

Abstract Novel reactions have been discovered and studied of C aliph. –Te bond scission in o -butyltellurobenzalanilines under the action of halogens, which afford 2-halogenotellurenyl- and 2-trihalogenotellurobenzalanilnes in high yields. The series of azomethines have been synthesized with different tellurium-containing groups in o -positions with respect to the CN bond. The effects of structural factors upon the length of N → Te intramolecular coordination bonds have been studied by the following methods: X-ray structural determinations, dipole moments, 1 H and 125 Te NMR spectroscopy and IR spectroscopy. In Te II derivatives, the shortest intramolecular N→ Te contact (2.23 A) is formed in 2-chlorotellurenyl derivatives XIIIb. Bis(2-formylphenyl)tellurium imines XIVa exist in the crystal form as 10-Te-3 telluranes, in which long intramolecular fractional N → Te bonds (2.70–2.72 A) have been detected, with the basicity of the imine N atom no practical effect on their length. The 125 Te NMR spectrum of the 15 N labelled bis[2-(phenyl)iminomethinylphenyl]telluride shows that in solution of this compound a very fast (on an NMR timescale), Te–N and Te ← N bond scrambling occurs owing to a dynamic equilibrium between the topomeric 10-Te-3 structures that apparently takes place via the 12-Te-4 tellurane intermediates. The intramolecular coordination bond in the Te iv derivative, (2-phenyliminomethinyl-phenyl)butylmethyl telluronium perchlorate, belongs to the longest Te → N bonds (2.75 A). For the first time, the 125 Te– 15 N spin-spin coupling constants are reported for a number of o -tellurated azomethines.

Chemical consequences of intramolecular Te ← N coordination in tellurium-containing aromatic azomethine derivatives

Abstract Owing to stabilization by Te ← N coordination in the aromatic tellurenyl compounds containing the azomethine function in the ortho position of the aryl ring, the synthesis of the novel organic tellurium compounds, tellurenyl azides and tellurenic acid esters and anhydrides becomes possible. The influence of the Te ← N coordination on the reactions of 2-butyltelluro- and 2-halogenotellurenylbenzalanilines is described.

Synthesis and structure of diorganyldiaryloxytelluranes with intramolecular Te ⋯ N coordination bonds

Abstract A wide series of diorganyldiaryloxytelluranes having an azomethine function in the position ortho to the tellurium atom have been synthesized by the reaction of diorganyldimethoxytelluranes with benzylidene- o -aminophenols. The X-ray structural investigation of the dimethylbis[2-(4-nitrobenzylideneimino)phenyloxy]tellurane indicates the presence of an intramolecular coordination bond Te ⋯ N. According to the dipole moment data and the 1 H, 125 Te, 14 N NMR spectra, in compounds VII, excluding those having nitro groups in the position para to the CHN bond, the Te ⋯ N coordination is retained in a non-polar solvent (benzene).

Molecular and crystal structure of 1-bromo-1-butyl-3H-2,1-benzoxatellurole

The molecular and crystal structure of 1-bromo-1-butyl-3H-2,1-benzoxatellurole was determined by x-ray diffraction structural analysis. Without taking account of secondary interactions, the molecule contains a tetracoordinated tellurium atom with bisphenoidal bond configuration. The angle between the axial bromine and oxygen atoms is 172.1°. The intermolecular Te...Br contacts (3.592 Å) connect the individual dimers into planar dieters, which expands the coordination about the tellurium atom to octahedral.

5H-1,2-oxatelluroles and their benzo analogs: Synthesis and reactions

Tetracoordinated derivatives of 2-halo-2-aryl-5H-1.2-oxatelluroles and 1-halo-l-butyl-3H-benz-2.1-oxatelluroles were synthesized by the oxidation of 3-aryltelluro-2 propen-l-ols and the dehydrogenation of 2-butyldihalotellurobenzyl alcohols. The halogen atoms in these compounds are readily replaced in nucleophilic substitution reactions. The reaction of benzoxatelluroles with bromine is accompanied by cleavage of O-Te bonds and leads, depending on the nature of the substituent at C(3), to 2-(butylbromotelluro)benzaldehyde or 2-(butyldibromotelluro)benzophenone.

Synthesis of phenoxatellurine derivatives

The reaction of dimedon enol acetate with tellurium tetrachloride gives derivatives of octahydrophenoxatellurine. The reaction of cyclohexanone enol acetate and methyl ethyl ketone with tellurium tetrachloride or aryltellurium trichloride gives the respective organotellurium trichloride and diorganotellurium dichloride.