A selective synthesis of hydroxyborate anions as novel anchors for zirconocene catalysts.

A new family of hydroxytris(pentafluorophenyl)borate anions B(C6F5)3OH associated with organic and aprotic cations c+ (imidazolium, pyrrolidinium and phosphonium) has been prepared by a general one-pot synthesis that implies the chloride borate analogues B(C6F5)3Cl[c]+. The [c]+B(C6F5)3OH salts have been isolated and fully characterized. The borate anion B(C6F5)3OH has been shown to protonate the Zr-Me bond in the Cp2ZrMe2 complex forming CH4 and the first published example of anionic Cp2Zr(Me)OB(C6F5)3 species. Standard spectroscopic methods demonstrate the covalent character of the Zr metal center and the anionic character of the boron atom. This protonolysis methodology using B(C6F5)3OH anion affords a new route for the incorporation of a covalently bonded anionic functionality on organometallic complexes. This provides a new way to immobilize transition metal complexes in ionic liquids.