From Carbene-Dithiolene Zwitterion Mediated B-H Bond Activation to BH 3 ·SMe 2 -Assisted Boron-Boron Bond Formation.

The 1:1 reaction of the carbene-stabilized dithiolene zwitterion 1 with BH 3 ·SMe 2 gave the dithiolene-based hydroborane 2 and the doubly hydrogen-capped CAAC species 3 via hydride-coupled reverse electron transfer processes. The mechanism of this transformation was probed computationally using density functional theory. The subsequent 2:1 reaction of 2 with 1 resulted in 4 and 3 , suggesting that 1 can mediate the B-H bond activation not only for BH 3 but also for monohydroboranes. In the presence of BH 3 ·SMe 2 , 2 was unexpectedly converted to the corresponding diborane(4) complex 5 through a dehydrocoupling reaction at an elevated temperature.