Synthesis and Characterization of Terpyridine-Supported Boron Cations: Evidence for Pentacoordination at Boron

Hypervalent
boron centers are proposed to be key intermediates in many stoichiometric
and catalytic reactions. However, structurally characterized examples
remain rare. We have isolated two new borocations with formal charges
of 1+ and 2+. Because the dicationic complex displays evidence of
pentacoordination at the boron center, we conclude that the interaction
is predominantly electrostatic and is a result of the highly electrophilic
dicationic boron atom.