E=SAs>Sb. These reactivities are parallel with the electrochemical oxidation potentials reported for Ph2E and with the first ionization potentials reported for Ph3M. The rate of Φ2Te was faster than that of Ph3P and slightly faster than that of Φ3Sb. From the reactivity of [Φ2E-Me]+ salts with nucleophiles, the E+–Me bond strengths were estimated to increase in the order E=Se
Tris(2,6-dimethoxyphenyl)telluronium chloride hydrate, [R3Te]Cl·nH2O 1a [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 R2TeCl23a, exclusively, from which R2TeX2 (X = Br 3b, I 3c 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 Å] are somewhat shorter than those reported for phenyl derivatives, and those of 3d [2.042(3) and 2.073(2) Å] 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 Å] are significantly shorter than the sum of the O and Te van der Waals radii [3.60 Å]. The 1H 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 ΔG‡ decreased in the order 3a (90 kJ mol−1 in DMSO-d6) > 3b (80 kJ mol−1 in DMSO-d6) > 3d (≥65 kJ mol−1 in CDCl3) > 3c (60 kJ mol−1 in CDCl3) ≥ 3d (59 kJ mol−1 in CD3CN).
三(2,6-二甲氧基苯基)碲鎂氯水合物 [R3Te]Cl·nH2O 1a [R = 2,6-(MeO)2C6H3, n = 2–2.5] 是通过 RLi 和 TeCl4 的反应制备的。它在热的 0.1 M 盐酸中分解,生成了仅有的化合物 R2TeCl2 3a,从中导出了卤素交换反应得到的 R2TeX2(X = Br 3b, I 3c 或 SCN 3d)。对 3a–3d 的 X 射线晶体学分析表明,这些化合物具有二重轴(3d 除外),具备基本的伪三角双锥配位结构,其中两个 R 基团和一对孤立电子占据赤道位置,而两个卤素原子占据顶角位置。3d 中的硫氰酸根通过硫与碲原子结合。对于 3a–3d 没有观察到分子间 Te⋯X的次级键。3a–3c 的 Te–C 键长 [2.09 ± 0.01 Å] 较已报道的苯基衍生物的键长稍短,而 3d 的 Te–C 键长 [2.042(3) 和 2.073(2) Å] 为所报道的最短。C–Te–C 键角远大于已报道值 [107.6(2)–104.37(9)°]。X–Te–X 键角非常接近 180°。3a–3d 的 Te⋯O 键长 [2.880–3.323 Å] 明显短于 O 和 Te 的范德瓦耳斯半径之和 [3.60 Å]。3a–3c 的 1H NMR 谱受卤素、溶剂和温度的影响,显示 R–Te 键的旋转因 R 基团与卤素原子之间的障碍而受到限制。活化能 ΔG‡的递减顺序为 3a (90 kJ mol−1 in DMSO-d6) > 3b (80 kJ mol−1 in DMSO-d6) > 3d (≥65 kJ mol−1 in CDCl3) > 3c (60 kJ mol−1 in CDCl3) ≥ 3d (59 kJ mol−1 in CD3CN)。