Amplifying Reactivity of Metal Hydrides: A Heterotrimetallic NiAl2(μ2‑H)2 Catalyst for the Dearomatization of N‑Heterocycles

Identifying methods to modulate the reactivity of metal hydrides is lacking yet highly desirable given the role they play in a plethora of catalytic applications. Herein we report novel methodology to amplify the reactivity of metal hydrides through the design of well-defined heterometallic bridged hydride species. Catalytic hydroboration of quinolines was dramatically altered by the addition of a secondary metal to bridge the Al–hydride species LAlH. Specifically, the addition of Ni­(COD)2 led to the formation of novel heterotrimetallic species 1 which features Ni participating in 3-center bonding with sterically accessible Al–H species and exhibits catalytic hydroboration of sterically encumbered quinolines and approximately a 400 times enhancement in catalytic reactivity in comparison to LAlH.