CO Capture by 2-(Methylamino)pyridine Ligated Aluminum Alkyl Complexes.

A set of novel, easily synthesized aluminum complexes, Al[κ-,2-(methylamino)pyridine]R (R = Et, Bu) are reported. When subjected to 1 atm of CO pressure, each hemilabile pyridine arm dissociates and facilitates cooperative activation of the CO substrate reminiscent of a Frustrated Lewis Pair. This reaction has limited precedent for Al/N based Lewis Pair systems, and this is the first system readily shown to sequester multiple equivalents of CO per aluminum center. The ethyl variant then reacts further, inserting a third equivalent of CO into the aluminum alkyl to generate an aluminum carboxylate. Examples of this type of reactivity are rare under thermal conditions. A joint experimental/computational study supports the proposed reaction mechanism.