Crystalline Plumbynes

Despite more than a century of organolead chemistry, all isolable organolead compounds have thus far been confined to Pb-C single bonds. Here we disclose the synthesis, structural authentication, and reactivity of room-temperature-stable plumbynes ([(CH₂)(NDipp)]₂PCPbAr; Ar = C₆H₃-2,6-Mes₂ or C₆H₃-2,6-Trip₂; Mes = mesityl; Trip = C₆H₂-2,4,6-^<i>i</i>Pr₃)─the heaviest group-14 heteronuclear analogues of alkynes. These molecules adopt a <i>trans</i>-bent P-C-Pb-C scaffold and exhibit a multiply bonded P-C-Pb motif. Strikingly, the Pb-C linkage exhibits diverse reactivity pathways: it can be saturated or cleaved depending on the reaction partner, the latter constituting a formal Pb-C/E-Cl (E = Si, Sn) bond-metathesis that furnishes carbene and stannyne products. Collectively, these findings close a long-standing gap in the chemistry of heteronuclear alkyne analogues and establish preliminary plumbyne reactivity as a platform for accessing rare main group species.