Comparative study of fluorinated triarylalanes and their borane counterparts

The chemistry of Lewis acids, in particular that of triarylboranes, has received unprecedented attention in recent years. Particularly in their role as the Lewis acid component of frustrated Lewis pairs (FLPs), boranes have shown astonishing properties, for example in their ability to bind H2 reversibly. With the current spotlight on main-group chemistry, the heavier aluminum homologs have not yet received much attention. Herein, we provide an overview of the synthesis, properties, and reactivities of fluorinated triarylalanes [Al(ArF)3] in direct comparison to their boron counterparts [B(ArF)3]. In part, the scarcity of studies on fluorinated triarylalanes could be attributed to their shock- and thermal-sensitive nature, which has hampered progress in this field. However, because of their enhanced Lewis acidity compared to their boron complements, they have shown promising behavior in the fields of FLPs and, more recently, frustrated radical pairs (FRPs). They are also capable of effectively catalyzing polymerizations and hydroboration reactions and have proven to be useful as aryl nucleophiles in stochiometric reactions.