318522-49-5Relevant academic research and scientific papers
Bis(2,6-dimethoxyphenyl)tellurium dihalides (CI, Br or I) and dithiocyanate: Crystal structure and temperature-dependent NMR spectra
Asahara, Masahiro,Tanaka, Masahito,Erabi, Tatsuo,Wada, Masanori
, p. 3493 - 3499 (2000)
Tris(2,6-dimethoxyphenyl)telluronium chloride hydrate, [R3Te]Cl-;)H2O la [R = 2,6-(MeO)2C6H3, n = 2-2.5] was prepared by the reaction of RLi and TeCl4. It decomposed in hot 0.1 M hydrochloric acid to give R2TeCI2 3a, exclusively, from which R2TeX2 (X = Br 3b, 13c or SCN 3d) were derived by halogen exchange. The X-ray crystallographic analyses of 3a-3d showed that these compounds have a twofold axis (except for 3d) with essentially pseudo-trigonal bypyramidal co-ordination with two R groups and a lone pair of electrons occupying the equatorial sites and two halogen atoms the apical sites. The thiocyanate groups in 3d bind to the tellurium atom via sulfur. No intermolecular Te ...X secondary bond was observed for 3a-3d. The Te-C bond distances of 3a-3c [2.09 ±0.01 A] are somewhat shorter than those reported for phenyl derivatives, and those of 3d [2.042(3) and 2.073(2) A] are the shortest ever reported. The C-Te-C bond angle is much larger [107.6(2)-104.37(9)°] than those reported. The X-Te-X bond angles are very close to 180°. The Te ...O distances of 3a-3d [2.880-3.323 A] are significantly shorter than the sum of the O and Te van der Waals radii [3.60 A]. The 'H NMR spectra of 3a-3c were halogen-, solvent-, and temperature-dependent showing that the rotation of R-Te bonds was restricted due to the barrier between R groups and halogen atoms. The activation energies AG? decreased in the order 3a (90 kJ mol-1 in DMSO-d6) > 3b (80 kJ mol-1 in DMSO-d6) > 3d (>65 kJ mor' in CDCl3) > 3c (60 kJ mol-1 in CDC13) > 3d (59 kJ mol-1 in CD3CN). The Royal Society of Chemistry 2000.
