Highly Lewis Acidic Bifunctional Organoboranes

Abstract

Chelating Lewis acids have not been developed to the same degree as multidentate Lewis bases. Nonetheless, such compounds have attracted interest due to their potential for the enhanced activation of basic substrates and the selective binding of anions. Organodiboryl compounds form a class of bidentate Lewis acids which have a long, but relatively underdeveloped history. Many examples exist where donor groups on boron serve to stabilize the Lewis acid centers. More recently, advances in the chemistry of diboryls with highly Lewis acidic boron centers substituted with perfluoroaryl groups have been made. In particular, compounds of general formula (F5C6)2B−linker−B(C6F5)2 have been prepared and their chemistry examined. In this Microreview, we survey the classes of bifunctional boron Lewis acids known, including their synthesis, properties and anion binding chemistry. Particular emphasis is placed on the role these Lewis acids play in olefin polymerization catalyst generation from simple metallocene precursors.