Trap-Free Halogen Photoelimination from Mononuclear Ni(III) Complexes

Halogen photoelimination reactions
constitute the oxidative half-reaction
of closed HX-splitting energy storage cycles. Here, we report high-yielding,
endothermic Cl2 photoelimination chemistry from mononuclear
Ni­(III) complexes. On the basis of time-resolved spectroscopy and
steady-state photocrystallography experiments, a mechanism involving
ligand-assisted halogen elimination is proposed. Employing ancillary
ligands to promote elimination offers a strategy to circumvent the
inherently short-lived excited states of 3d metal complexes for the
activation of thermodynamically challenging bonds.