Activation of Small Molecules by Compounds that Contain Triple Bonds Between Heavier Group-14 Elements.
Dimetallynes (RE≡ER; E=Si, Ge, Sn, Pb), i.e., systems that contain triple bonds between heavier group-14 elements represent the heavier homologues of alkynes. The high reactivity of disilynes, digermynes, distannynes, and diplumbynes can be interpreted in terms of their unique bonding situation, which includes a trans-bent structure, a small HOMO-LUMO gap, a partial diradical character, their electronic nature, and interactions between bulky substituents. Relatively recent developments in the area of sterically demanding substituents have permitted isolating some stable compounds with a triple bond between heavier group-14 elements. The structural features of these triple-bonded compounds and their reactivity toward small molecules have been investigated using experimental and theoretical approaches. This review focuses on recent developments regarding the reactivity of stable compounds with a triple bond between heavier group-14 elements toward small molecules, where the results were examined using quantum chemical methods. A comprehensive review on carbon chemistry is beyond the scope of this focus review.