A Self‐Assembled Trinuclear Co(II) Catalyst for Efficient C─H Activation of Benzaldehydes under Solvent‐Free Condition

Abstract A trinuclear, self‐assembled Co(II) coordination solid with the formula [Co 3 (BTC) 2 (BPY) 4 (H 2 O) 10 .]· BPY 4H 2 O ( 1 ) [BTC = 1,3,5‐benzenetricarboxylate, BPY = 4,4′‐bipyridine] has been developed. Diffraction studies revealed that ( 1 ) features two crystallographically distinct Co 2+ centers connected through BPY bridges, resulting in a trinuclear complex structure. The centrosymmetric trinuclear [Co 3 (BTC) 2 (BPY) 4 ] unit together with uncoordinated BPY molecules generate a 2D stacked structure. Theoretical calculations also support noncovalent interactions between the aromatic ring of uncoordinated BPY units and the trinuclear unit, as well as H‐Bonding interactions. The compound 1 exhibits remarkable catalytic activity that facilitates the C─H activation of benzaldehyde in the presence of TBHP, yielding symmetric anhydrides. This green approach demonstrates a broad substrate scope under solvent‐free conditions (water is added for solid reactant substrates). The investigated catalytic protocol is homogenous, straightforward, and efficient. In addition to that, mechanistic studies suggest that the catalytic reactions follow a radical pathway. This protocol also features short reaction time along with wide functional group tolerance, highlights its practical utility.