Ligation of Boratabenzene and 9-Borataphenanthrene to Coinage Metals.

The reactions of boratabenzene and borataphenanthrene anions with group 11 PhPMCl reagents furnished η coordination complexes, with the exception of the copper boratabenzene species that adopted an η mode. The binding of arene ligands to copper in an η manner is rare, and altering the ancillary ligand on copper to an N-heterocyclic carbene switched the binding of the boratabenzene to η, indicating that such ligands are capable of vacating coordination sites. The η coordination complexes bind side-on, akin to olefins, via a borataalkene unit, although with the carbon atom much more proximal to the metal center than boron.