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

研究了二泰脲烷Ar_2Te^+-O-Te^+Ar_2 2X^-2 （Ar=p-tolyl）与一碲氧化物1、一硒氧化物7和一羧酸盐10的反应，生成主链顶端带有高价Te-O键的低聚羟基脲烷。随着反阴离子（X^-）亲核性的降低，2 - a-d的核磁共振化学位移向下移动。这一结果既反映了2的阳离子性质，也反映了2在Te原子上的反应性。2a （X^-=CF_3SO_3^-）与1、2、3或4等量的碲氧化物1a （Ar=对甲基）反应，分别选择性地得到低聚碲氧烷三聚体3a、四聚体4a、五聚体5a或六聚体6a。相比之下，过量1a的2b （X^-=CF_3CO_2^-）反应只能得到三聚体3b。通过2a与4a和2a与1b （Ar=Ph）反应的交叉实验证实了低聚telluroxanes之间的平衡。DFT计算也支持了低聚碲氧烷的反应性和平衡性质。多n / 2a与1或2等量的硒酸盐7的反应，分别产生了硒酸盐-二甲基溴二烷三聚体8和双（硒酸盐）-二甲基溴二烷四聚体9。通过交叉实验证实了这两种低聚乙醇烷之间的平衡，发现在CD_3CN中，-40℃下，2a与7形成8的缔合常数为K_a=(2.18±0.12)x10^4 M^<-1>。2a与2个等量的羧酸10a-d反应，分别得到二磺酰黄酮（羧酸酯）加合物11a-c和二酰基二羧酸酯加合物12b-d的混合物，其产物比例取决于10的吸电子能力。三氟烷3a与2倍的10a-d反应均得到11a-d。与邻苯二甲酸酯14反应得到[2+2]组装的大环多碲烷15，并通过x射线晶体学分析得到证实。结果表明，σ^*-n轨道相互作用在二泰脲烷的反应性和自组装的低聚乙醇烷的形成中起着重要作用。因此，杂原子间通过σ^*-n轨道相互作用形成的高价键可以作为一种新的用于分子组装的超分子合成体。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