Efficient and reusable catalysis of benzylic C-H oxidation over layered [Co 5 (OH) 6 ] 4+ derivatives.

Aerobic oxidation of benzylic C(sp 3 )-H bonds in a green and heterogeneous manner is a major target in organic catalysis. Herein, we report the synthesis of 3D coordination polymers containing [Co 5 (OH) 6 ] 4+ layers, affording reusable and efficient oxidation of ethylbenezene and tetralin by using O 2 as the oxidant. Moreover, the cleavage of Co II -carboxylate bonding renders atomically thin cobaltate nanosheets and enhanced catalytic performance. This is one of the top catalytic performances for Co II -catalyzed benzylic C(sp 3 )-H oxidation (∼0.02 mol% Co and 76% conversion for nanosheets), ascribed to the exposed, accessible and coordinatively unsaturated Co II species.