Reactivity and Properties of Cationic Ditelluroxane : Application to Polytelluroxane and Molecular Assembly

研究了Ar_2Te^+-O-Te^+Ar_2 2X^-2(Ar=对甲苯基)与主链上生成高价Te-O尖端键的低聚硫氧杂环氧烷的反应.随着反阴离子(X^-)亲核性的降低，2a-d的化学位移下移.2a(X^-=Cf_3SO_3^-)与1，2，3或4个亚碲酸根1a(Ar=对甲苯基)的反应分别选择性地合成了低聚硫杂环氧烷三聚体3a、四聚体4a、五聚体5a或六聚体6a。相反，2b(X^-=CF3CO2^-)与过量的1a反应只生成三聚体3b。2a与4a、2a与1b(Ar=Ph)反应的交叉实验证实了低聚硫杂环氧烷之间的平衡。密度泛函理论计算也支持低聚硫杂环氧烷的反应性和平衡性。反应性…更多的2a中的n与1或2当量的硒氧化合物7分别专属地产生了硒氧杂三聚体8或双(硒氧杂)二硫杂环氧烷四聚体9。通过交叉实验证实了低聚硫杂环氧烷之间的平衡，得到2a与7形成8的缔合常数为K_a=(2.18±0.12)×10~(-4)M^&lt；-1&gt；在-40℃的Cd_3CN中，2a与2当量的羧酸盐10a-d反应，分别得到二硫杂环双(羧酸盐)加合物11a-c和二芳基二酸碲烷12b-d的混合物，其产物的比例取决于10的吸电子能力。三氢呋喃3a与2当量10a-d的反应在所有情况下都得到11a-d。2a与1当量的邻苯二甲酸酯14反应得到[2+2]组装的大环多碲15，结果表明，σ^*-n轨道相互作用在二硫杂环氧烷的反应活性和自组装低聚硫杂环氧烷的形成中起着重要的作用。因此，杂原子中通过σ^*-n轨道相互作用形成的超价键可以作为一种新的超分子合成子用于分子组装。较少

The reactions of ditellturoxanes Ar_2Te^+-O-Te^+Ar_2 2X^-2 (Ar=p-tolyl) with a telluroxide 1, a selenoxide 7, and a carboxylate 10 that produce oligochalcogenoxanes bearing a hypervalent Te-O apical linkage in the main chain were sttudied.The ^<125>Te NMR chemical shifts of 2a-d were shifted downfield with decreasing the nucleophilicity of counteranions (X^-). This result reflects both the cationic character and the reactivity on the Te atoms of 2. The reaction of 2a (X^-=CF_3SO_3^-) with 1, 2, 3, or 4 eqtuiv of a tellturoxide 1a (Ar=p-tolyl) selectively gave oligotelluroxanes trimer 3a, tetramer 4a, pentamer 5a, or hexamer 6a, respectively. By contrast, the reaction of 2b (X^-=CF_3CO_2^-) with an excess of 1a afforded only trimer 3b. Equilibrium between oligotelluroxanes was confirmed by the crossover experiments for the reactions of 2a with 4a and of 2a with 1b (Ar=Ph). The reactivity and equilibritum properties of oligotelluroxanes were also supported by DFT calculations.The reactio … More n of 2a with 1 or 2 equiv of a selenoxide 7 exclusively produced a selenoxa-ditelluroxane trimer 8 or a bis (selenoxa)-ditelluroxane tetramer 9, respectively. Eqtuilibrium between these oligochalcogenoxanes was confirmed by the crossover experiments, The association constant of 2a with 7 forming 8 was found to be K_a=(2.18±0.12)x10^4 M^<-1> in CD_3CN at -40℃.The reaction of 2a with 2 equiv of carboxylates 10a-d gave a mixture of ditelluroxanebis (carboxylate) adducts 11a-c and diaryldicarboxytelluranes 12b-d, respectively, the prodtuct ratio of which depends on the electron-withdrawing ability of 10. The reaction of a tritelluroxane 3a with 2 equiv of 10a-d afforded 11a-d in all cases.The reaction of 2a with 1 equiv of phthalate 14 gave a [2+2]-assembled macrocyclic multitellurane 15, which was confirmed by X-ray crystallographic analysis.The present restults suggest that σ^*-n orbital interaction plays an essential role in the reactivity of ditellturoxanes and formations of self-assembled oligochalcogenoxanes. Thus, hypervalent bonds via σ^*-n orbital interactiont in heteroatoms could serve as a new supramolecular synthon for molecular assembly. Less