These days, tailor-made inorganic polymers (e.g. polysiloxanes) are applied in various working fields. Among such materials, macromolecules with boron-containing main chains are under-represented. In 1991, Chujo synthesized the first monoborane-containing polymer chain with high molar mass by using a hydroboration reaction as a versatile synthetic strategy. For practical applications, these systems require sufficient air and water stability. In 1998, Chujo once again used hydroboration to prepare a catenated organoborane with such characteristics. There are currently no polymers known with an electron-precise boron-boron bond in the main chain. In this work, we present the synthesis of the novel alkyne-containing bis(dimethylamino)diborane(4) 1 and its oligomerization by hydroboration of the terminal alkyne using an aryl(dihydro)borane. The resulting system 2 was analyzed by NMR and IR spectroscopy as well as size exclusion chromatography (Mn = 5000 Da; PDI = 1.8). Additionally, by the use of a diaryl(hydro)borane the small-molecule model compound 3 was prepared, fully analyzed and compared with the catenated species.

Controlled synthesis of oligomers containing main-chain B(sp2)-B(sp2) bonds

ACS Spring 2022

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