A Ni–Al Hydride Cluster Bearing Site-Differentiated Al Centers: Demonstration of Olefin Insertion and Alkyl Transfer

Heterometallic assemblies have been key in uncovering
new modes
of reactivity, with synergistic effects resulting from main-group
metals such as Al drawing particular attention given the diverse ligand
modalities accessible to aluminum. Utilizing a reducing Al-dihydride
metalloligand LAlH2 and bis (1,5-cyclooctadiene)nickel(0),
we report cluster 1, [LNiAl]3H5R (R = 4-cyclooctenyl). The cluster core features Al/Al–H
moieties asymmetrically capping a Ni3 plane and coordinating
to a Ni–Ni edge. The Al centers display electronically differentiating
sites through Al–H addition, olefin insertion, and alkyl transfer.
Crystallographic, DFT, and spectroscopic tools establish the presence
of three distinct Al centers that adopt sigma-donating alane, sigma-accepting
alane, and nonalane character.