Extreme Oxatriquinanes: Structural Characterization of α‑Oxyoxonium Species with Extraordinarily Long Carbon–Oxygen Bonds

The first stable α-oxyoxonium species have been synthesized and characterized. Strong donation of nonbonding electrons on oxygen into the adjacent σ*­(C–O+) orbital was predicted by modeling to result in unheard of carbon–oxygen bond lengths. The kinetic stability of the triquinane ring system provides a platform upon which to study these otherwise elusive species, which are evocative of intermediates on the acetalization reaction pathway. Crystallographic analysis of the α-hydroxy and α-methoxy oxatriquinane triflates reveals 1.658 and 1.619 Å C–O+ bond lengths, respectively, the former of which is a new record for the C–O bond.

首例稳定的α-氧代氧鎓（α-oxyoxonium）物种已被成功合成并表征。通过计算建模预测，氧原子上的非键电子对向相邻的σ*(C–O+)轨道发生强电子给予作用，将生成前所未有的碳-氧键长。三奎烷（triquinane）环系的动力学稳定性为研究这类原本难以捉摸的物种提供了理想平台，这类物种可类比于缩醛化反应路径中的反应中间体。对α-羟基与α-甲氧基氧杂三奎烷三氟甲磺酸盐（oxatriquinane triflate）的晶体结构分析结果显示，其C–O+键长分别为1.658埃和1.619埃，其中前者创下了C-O键的新纪录。