Ligation of Boratabenzene and 9-Borataphenanthrene to Coinage Metals

The reactions of boratabenzene and borataphenanthrene anions with group 11 Ph3PMCl reagents furnished eta(2) coordination complexes, with the exception of the copper boratabenzene species that adopted an mode. The binding of arene ligands to copper in an eta(6) manner is rare, and altering the ancillary ligand on copper to an N-heterocyclic carbene switched the binding of the boratabenzene to eta(2), indicating that such ligands are capable of vacating coordination sites. The eta(2) 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.