One-Electron (2c/1e) Tin···Tin Bond Stabilized by <i>ortho</i>-Phenylenediamido Ligands

Odd-electron bonds, i.e., the two-center, three-electron (2c/3e), or one-electron (2c/1e) bonds, have attracted tremendous interest owing to their novel bonding nature and radical properties. Herein, complex [K(THF)₆][LSn:···Sn:L] (<b>1</b>), featuring the first and unsupported 2c/1e Sn···Sn σ-bond with a long distance (3.2155(9) Å), was synthesized by reduction of stannylene [LSn:] (L = <i>N</i>,<i>N</i>-dpp-<i>o</i>-phenylene diamide) with KC₈. The one-electron Sn–Sn bond in <b>1</b> was confirmed by the crystal structure, DFT calculations, EPR spectroscopy, and reactivity studies. This compound can be viewed as a stabilized radical by delocalizing to two metal centers and can readily mediate radical reactions such as C–C coupling of benzaldehyde.