The Chemistry of Low-Valent Organoaluminum Species

During the past 25 plus years, room-temperature stable aluminum(I) and (II) compounds have become available through standard organometallic techniques, and their reactivity has been explored in much detail. The chemistry of aluminum(I) compounds may be viewed as that of a very reactive carbene (singlet and triplet, depending on the substrate). Typical reactions involve insertions into various EE or EX bonds and adduct formation with Lewis acids. Aluminum(II) compounds are generally dialumenes (R2AlAlR2) featuring an AlAl single bond. Their chemistry is similar to that of alanes (R3Al) with respect to substitutions and Lewis acid base chemistry but with a strong redox component. In many cases, substrates insert into the AlAl bond in a formally oxidative manner. Keywords: aluminum; low oxidation state; dialumane; dialumene; reduction; insertion; Lewis acid; Lewis base; carbene; insertion