Large shortening of the lead-lead bond in a diplumbyne upon its one-electron reduction

Abstract

One-electron reduction of the diplumbyne AriPr6PbPbAriPr6, 1, with KC8 in the presence of 18-crown-6 affords crystals of the salt of its radical anion, [K(18-crown-6)][AriPr6PbPbAriPr6], 2, AriPr6 = C6H3-2,6-(C6H2-2,4,6-iPr3)2. Its X-ray crystal structure shows that the Pb–Pb distance becomes remarkably shortened by ca. 0.25 Å upon reduction, consistent with population of the π-bonding LUMO of 1. The radical nature of 2 is confirmed by its electron paramagnetic resonance spectrum which shows coupling of the unpaired electron to both 207Pb nuclei.