Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1-5/10, 8093, Zürich, Switzerland.
Lehn Institute of Functional Materials (LIFM), School of Chemistry, Sun Yat-Sen University, 510275, Guangzhou, China.
Angew Chem Int Ed Engl. 2023 Mar 27;62(14):e202214548. doi: 10.1002/anie.202214548. Epub 2023 Feb 27.
Reaction of the imidazolium-stabilized diphosphete-diide IDP with trityl phosphaalkyne affords a mixture which contains the molecules 1 a and 1 b with a central C P core, which formally carries a two-fold negative charge. In order to avoid the formation of an antiaromatic 8π electron system within a conjugated dianionic six-membered [C P ] ring, 1 a adopts a bicyclic [3.1.0] and 1 b a tricyclic [2.2.0.0] structure which are in a dynamic equilibrium. 1 a, b can be reversibly oxidized to a triphosphinine dication [5] with a central flat aromatic six-membered C P ring. This two-electron redox reaction occurs in two single-electron transfer steps via the 7π-radical cation [4]⋅ , which could also be isolated and fully characterized. The profound reversible structural change observed for the two-electron redox couple [5] /1 a, b is in sharp contrast to the C H /[C H ] couple, which undergoes only a modest structural deformation.
咪唑鎓稳定的二膦二化物（IDP）与三苯甲基膦炔反应得到的混合物中包含具有中心 CP 核的分子 1a 和 1b，该 CP 核形式上带有两个负电荷。为了避免在共轭二阴离子六元环[CP]中形成反芳香性 8π电子体系，1a 采用双环[3.1.0]结构，而 1b 采用三环[2.2.0.0]结构，两者处于动态平衡中。1a、1b 可以可逆地氧化为具有中心平面芳香六元环 CP 的三膦亚宁双阳离子[5]。这个两电子氧化还原反应通过 7π-自由基阳离子[4]·发生在两个单电子转移步骤中，[4]·也可以被分离并进行完全表征。对于二电子氧化还原对[5]/1a、1b 观察到的深刻的可逆结构变化与 CH/[CH]对形成鲜明对比，后者仅经历适度的结构变形。
