Synthesis, characterisation and structural aspects of some symmetrical organotellurium halides based on Bis(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)telluride

GRAPHICAL ABSTRACT

ABSTRACT

Bis(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)telluride (2) has been synthesised in good yield by reacting 1-(2-chloroethyl)-3,5-dimethylpyrazole with in situ prepared sodium telluride, Na₂Te in an aqueous solution. A number of new organotellurium halides from bis(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)telluride have been synthesised by using different halogenating reagents. Reaction of 2 with bromine gave bis(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)telluride dibromide (5a) in addition to unexpected product bis(2-(4-bromo-3,5-dimethyl-1H-pyrazol-1-yl)ethyl)telluride dibromide (5b). All compounds were characterized by different spectroscopic techniques viz., ¹H, ¹³C, ¹²⁵Te NMR, Mass spectroscopy, IR and CHN analysis. EDXRF studies have also been employed to confirm the identity of 5a and 5b. Thermal gravimetric analysis of bis(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)telluride (IV) chloride (4) and bis(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)telluride (IV) iodide (5c) reveals the thermal stability of these molecules above 100°C. The X-ray studies of 5c shows trigonal bipyramidal geometry around tellurium atom and intermolecular secondary interaction viz., C-H π stacking between H23A and C22 showing a supramolecular packing between two molecules.

KEYWORDS:

• 3,5-Dimethylpyrazole
• tellurium
• organotellurium halides
• halogenating reagents
• EDXRF (Electron Diffraction X-Ray Fluorescence)

Acknowledgment

KKB would like to acknowledge thanks to CSIR, New Delhi for Emeritus Scientist, vide sanction letter no. {21(0967)/13/EMR-II} and UGC, New Delhi vide sanction letter no. 43–254/2014 (SR) for financial assistance. SP is thankful to UGC for financial assistance.