Strongly Polarized Iridium-Aluminum Pairs: Unconventional Reactivity Patterns Including CO Cooperative Reductive Cleavage.

The iridium tetrahydride complex CpIrH reacts with a range of isobutylaluminum derivatives of general formula Al(Bu)(OAr) ( = 1, 2) to give the unusual iridium aluminum species [CpIrHAl(Bu)(OAr)] () via a reductive elimination route. The Lewis acidity of the Al atom in complex is confirmed by the coordination of pyridine, leading to the adduct [CpIrHAl(Bu)(OAr)(Py)] (). Spectroscopic, crystallographic, and computational data support the description of these heterobimetallic complexes and as featuring strongly polarized Al(III)-Ir(III) interactions. Reactivity studies demonstrate that the binding of a Lewis base to Al does not quench the reactivity of the Ir-Al motif and that both species and promote the cooperative reductive cleavage of a range of heteroallenes. Specifically, complex promotes the decarbonylation of CO and AdNCO, leading to CO (trapped as CpIrH(CO)) and the alkylaluminum oxo ((Bu)(OAr)Al(Py) ()) and ureate ({Al(OAr)(Bu)[κ-(N,O)AdNC(O)NHAd]} ()) species, respectively. The bridged amidinate species Cp*IrH(μ-CyNC(H)NCy)Al(Bu)(OAr) () is formed in the reaction of with dicyclohexylcarbodiimine. Mechanistic investigations via DFT support cooperative heterobimetallic bond activation processes.