title: Isolation and reversible dimerization of a selenium-selenium three-electron σ-bond.
abstract: Three-electron σ-bonding that was proposed by Linus Pauling in 1931 has been recognized as important in intermediates encountered in many areas. A number of three-electron bonding systems have been spectroscopically investigated in the gas phase, solution and solid matrix. However, X-ray diffraction studies have only been possible on simple noble gas dimer Xe∴Xe and cyclic framework-constrained N∴N radical cations. Here, we show that a diselena species modified with a naphthalene scaffold can undergo one-electron oxidation using a large and weakly coordinating anion, to afford a room-temperature-stable radical cation containing a Se∴Se three-electron σ-bond. When a small anion is used, a reversible dimerization with phase and marked colour changes is observed: radical cation in solution (blue) but diamagnetic dimer in the solid state (brown). These findings suggest that more examples of three-electron σ-bonds may be stabilized and isolated by using naphthalene scaffolds together with large and weakly coordinating anions.
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Senwang
authors.initials: S
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Xingyong
authors.initials: X
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Yuanting
authors.initials: Y
authors.lastname: Su
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Yunfan
authors.initials: Y
authors.lastname: Qiu
authors.affiliation: Jiangsu Key Laboratory for the Chemistry of Low-dimensional Materials, School of Chemistry and Chemical Engineering, Huaiyin Normal University, Huai'an 223300, China.
authors.forename: Zaichao
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Xinping
authors.initials: X
authors.lastname: Wang