Synthesis and some reactivity studies of germanium, tin and lead analogues of alkynes

Recently published work on the syntheses and reactivity of the germanium, tin, and lead analogues of alkynes is summarized. The heavier Group 14 ‘alkynes’ are stabilized by bulky terphenyl ligands and are thermally robust crystalline solids. However, they are extremely reactive and their reactivity decreases in the order Ge > Sn > Pb. Their spectroscopy and reactivity patterns suggest that the germanium species, in particular, has considerable diradical character. This hypothesis is also supported by preliminary density functional theory calculations.