An anionic nickel-aluminium dihydride complex exhibiting cooperative catalytic behaviour.

In nickel catalysis, aluminium additives have found ample use in aiding the activation and functionalisation of strong bonds. However, despite the common occurrence of both nickel hydride and aluminium hydride species in homogeneous catalysis, heterobimetallic NiAl hydride complexes have only been scarcely studied. Moreover, uses of such complexes as catalysts are extremely rare and their potential to enable cooperative reactivity remains largely underexplored. Opening new ground in this area here we report a novel and stable low valent NiAl dihydride 'ate' complex obtained by reacting a Ni(0) tris(olefin) precursor with LiAlH2(HMDS)2 (HMDS = hexamethyldisilazanide) and explore its stoichiometric reactivity towards a range of unsaturated substrates. By switching on bimetallic cooperation, this nickelate complex is able to catalyse alkene isomerisation, displaying superior reactivity to the monometallic counterparts on their own. Mechanistic investigations incidate that the main bond making/breaking steps take place on nickel while the aluminium dihydride moiety functions as a hydride reservoir.