STEREOSELECTIVE SYNTHESIS, MOLECULAR-STRUCTURE AND NBO ANALYSES OF CIS-3,5-DI(CHLOROMETHYL)-1,4-OXATELLURANE(IV) 4,4-DICHLORIDE

Tellurium tetrachloride and diallyl ether give stereoselectively cis-3 ,5-di(chloromethyl)-1,4-oxa-tellurane(IV) 4,4-dichloride. The structur e was determined by single crystal X-ray diffraction. The coordination around the Te-IV ion is a distorted psi trigonal bipyramid with two c hlorine atoms in the axial positions. Two of the equatorial sites are occupied by carbon atoms, with the lone electron pair located at the t hird position. The six-membered heterocycle displays a chair conformat ion. The crystal structure consists of ribbons with Te ... Cl contacts . The NBO (Natural Bond Order) analyses carried out by both HF/STO-3G and HF/LANL1DZ level of theory gave different results. No intermolecu lar interaction (> 1 kcal mol(-1)) was found by HF/STO-3G, whereas th e main interaction can be seen between a lone pair of Cl(2) and the an tibonding orbital between Tell) and C(1) by RHF/LANL1DZ (1.1 kcal mol( -1)). (C) 1997 Elsevier Science Ltd.