Controlled Synthesis of Oligomers Containing Main-Chain B(sp(2))-B(sp(2)) Bonds

A number of novel alkynyl-functionalized diarylbis(dimethylamino)diboranes(4) are prepared by salt metathesis, and the appended alkynyl groups are subjected to hydroboration. Their reactions with monohydroboranes lead to discrete boryl-appended diborane(4) species, while dihydroboranes induce their catenation to oligomeric species, the first known examples of well-characterized macromolecular species with B-B bonds. The oligomeric species were found to comprise up to ten repeat units and are soluble in common organic solvents. Some of the oligomeric species have good air stability and all were characterized by NMR and vibrational spectroscopy and size-exclusion chromatography techniques.

Automated summary

Novel alkynyl-functionalized diarylbis(dimethylamino)diboranes(4) were prepared by salt metathesis, and their appended alkynyl groups underwent hydroboration to yield discrete boryl-appended diborane(4) species when reacted with monohydroboranes. Conversely, reactions with dihydroboranes led to the formation of oligomeric species with B-B bonds, with some exhibiting good air stability and solubility in common organic solvents. These oligomeric species, characterized by NMR, vibrational spectroscopy, and size-exclusion chromatography, can contain up to ten repeat units.