1,1-polymerization of acetylene

The polymerization of alkynes has long been a cornerstone of materials science, yielding a plethora of π-bond-rich materials and underpinning the 2000 Nobel Prize in Chemistry. While 1,2-polymerization of alkynes via 1,2-addition has been extensively studied, the 1,1-polymerization of carbon carbon triple bonds remains a formidable challenge due to the necessity of an alkyne rearrangement step during polymerization. Here we report the 1,1-polymerization of acetylene gas through a Cd-catalyzed iterative 1,1-carboboration process, achieving a broad terminal functionalization scope and functional group compatibility. This product, 1,1-polyacetylene (1,1-PA), also named as dendralene, exhibits unique physical and chemical properties, including an explosive tendency, distinguishing it from the 1,2-polyacetylene (1,2-PA) counterparts. Alkynes are well known to undergo linear 1,2-addition polymerisations, but their 1,1 addition is much rarer and more challenging. Here, the authors use a Cd-catalysed 1,1-carboboration process to polymerise acetylene via 1,1-addition.