# Turning the Tables: Ligand-Centered Hydride Shuttling in Organometallic BIP–Al Systems

## TL;DR

This paper introduces a new system for reversible hydride exchange using organometallic complexes, mimicking natural redox cofactors.

## Contribution

A new platform for ligand-centered hydride shuttling is established, inverting traditional metal-ligand roles.

## Key findings

- Cationic and neutral organoaluminum complexes can reversibly exchange hydrides.
- Strong reducing agents and electrophiles enable controlled interconversion between complex forms.
- The system mimics natural NAD(P)H/NADP+ cofactor behavior for hydride transfer.

## Abstract

The reversible storage and release of hydride equivalents
remains
a central challenge in the design of biomimetic redox systems. Cationic
2,6-bis­(imino)­pyridine organoaluminum complexes [(4-R-BIP)­AlR2]+ (where R = H; R′ = Me, 1a; R′ = Et, 1b; R = Bn; R′ = Me, 1c) and their neutral 2,6-bis­(imino)-4-R-dihydropyridinate
counterparts [(4-R-HBIP)­AlR2] 2a-c are presented as chemically
reversible hydride exchangers. Interconversion between these systems
is achieved through strong reducing agents such as M+[HBEt3]− (where M = Li; Na) or
LiAlH4, while powerful electrophiles like B­(C6F5)3 or cationic trityl salts Ph3C+ enable the reverse transformation, with the latter
providing complete selectivity. Overall, this reversible hydride exchange
mirrors natural NAD­(P)­H/NADP+ cofactor system. These findings
establish a new platform for ligand-centered hydride shuttling, where
the metal fragment acts as a passive modulatorinverting the
traditional roles assigned to metal and ligand.