Isolation and Characterization of Persistent Radical Cation and Dication of 2,7-Bis(dianisylamino)pyrene

Orbital interaction between 2,7-pyrenylene
and two nitrogen redox-active
centers effectively reduces the energy difference between HOMO and
HOMO–1, both of which were distributed over the two nitrogen
centers. In fact, one- and two-electron oxidation of 2,7-bis­(dianisylamino)­pyrene 3 generated a persistent radical cation and a persistent dication,
respectively, and we succeeded in the isolation and single crystal
X-ray structural analyses of all three oxidation states. The radical
cation was considered as a spin and charge delocalized mixed-valence
compound with a semiquinoidal structure. The dication was in an open-shell
singlet state with a small singlet–triplet energy gap. The
molecular and electronic structures for all three oxidation states
of 3 were studied in comparison with the data reported
for each oxidation state of closely related bis­(triarylamine)­s, of
which structures were determined by X-ray crystallography.

2,7-芘亚基与两个氮基氧化还原活性中心之间的轨道相互作用，可有效降低最高占据分子轨道（Highest Occupied Molecular Orbital，HOMO）与最高占据分子轨道-1（HOMO-1）之间的能级差，二者均分布于两个氮中心之上。事实上，对2,7-双(二茴香基氨基)芘3进行单电子与双电子氧化，可分别生成稳定的自由基阳离子与稳定的双阳离子；我们成功分离了该化合物三种氧化态的样品，并完成了其单晶X射线结构分析。该自由基阳离子被认为是具有半醌式结构、自旋与电荷离域的混合价化合物；该双阳离子则处于单重态-三重态能隙较小的开壳层单重态。本研究针对3的三种氧化态的分子与电子结构，与已报道的、经X射线晶体学确定结构的结构相近双(三芳基胺)类化合物各氧化态的数据进行了对比分析。