O. E. Kompan

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.

Synthesis and structure of β-tellurovinylcarbonyl compounds

Abstract By coupling β-chlorovinylcarbonyl compounds or β-acylvinyltriethylammonium chlorides with arene (alkene) tellurolates and lithium telluride β-organyltellurovinyl aldehydes, ketones I and bis(β-acylvinyl) tellurides II correspondingly have been prepared. β-Methyltellurovinyl aldehyde VI is readily oxidized by halogens, giving rise to previously undescribed β-methyldihalogenotellurovinyl aldehydes IX, which convert to the respective β-halogenotellurenylvinyl aldehydes X via elimination of a molecule of methyl halogenide. Regardless of the initial configuration at the Cβ center of the β-chlorovinylcarbonyl compounds, the nucleophilic vinylic substitution reaction results in the formation exclusively of Z-isomers of β-organyltellurovinyl aldehydes and ketones. The stereochemical outcome of this reaction is explained in terms of the addition—elimination mechanism of the nucleophilic vinylic substitution reaction, as a consequence of strong stabilization of the intermediate carbanions XVIII by intramolecular coordination of O → Te bonds. For the same reason, nucleophilic addition of arenetellurolate anions to a triple bond of α-acetylenic aldehydes and ketones occurs stereospecifically, affording exclusively Z-(β-aryltellurovinylcarbonyl) diastereomers. The crystal and molecular structures of β-(4-ethoxyphenyltelluro)-β-phenylpropenal Ip and its N-(4-methylphenyl) imine V have been studied by X-ray. Both compounds exist in the crystal as Z-diastereomers, the tellurium centers possessing a T-shaped configuration due to the formation of intramolecular coordination corresponding to O → Te (2.725 A) and N → Te (2.771 A) bonds.

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.

Molecular and crystal structure of 1-phenyl-3-methyl-5-(o-hydroxyphenyl)-1,2,4-triazole

A choice between the possible mechanisms of the recyclization of 4-oxo-1,3-benzoxazine salts due to reaction with phenylhydrazine was made based on the x-ray structure of 1-phenyl-3-methyl-5-(o-hydroxyphenyl)-1,2,4-triazole.

Ethynyl carbonium ions. 1. Reaction of 2.6-diaryl-4-phenylethynylpyrulium perchlorates with oxygen-containing nucleophiles

When 2,6-diaryl-4-phenylethynylpyrylium perchlorates are refluxed in water, methanol, or ethanol, they are converted to monomethinecyanines, the formation of which is explained by hydration of the phenylethynyl group and subsequent [2+2]-cycloaddition of the resulting 2,6-diaryl-4-benzoylmethylenepyrans to the starting pyrylium salt. The corresponding pyridine derivatives were obtained by the action of ammonia and aniline on the monomethinecyanines. The IR and PMR spectra of the compounds and the results of x-ray diffraction analysis of 2,6-diphenyl-4-[1′-(2″,6″-diphenyl-4″-pyranylidene)-2′-phenyl-3′-benzoylallyl]pyridine are presented.