Synthesis and Reactivity of a Bis(hydroxido)‐Bridged Dicopper(II) Complex: Hydrolysis of Carboxylate Esters and Coordination Polymer with Phosphate Diester

Anaerobic reaction between solution‐generated copper(I) species ‘[(L 3 )‐Cu I (MeCN)] + ’ (L 3 is an unsymmetrical tridentate ligand; methyl[2‐(2‐pyridyl)ethyl](2‐pyridylmethyl)amine) and dry O 2 in CH 2 Cl 2 , after usual workup under a dinitrogen atmosphere, afforded a green microcrystalline solid. Recrystallization of this air‐sensitive solid from MeCN/diethyl ether led to isolation of [{(L 3 )‐Cu II (μ‐OH)} 2 ](ClO 4 ) 2 •MeCN ( 1 •MeCN). Structural analysis of 1 •MeCN reveals a μ‐dihydroxido‐bridged dicopper(II) complex with a Cu⋯Cu separation of 2.9088(12) Å. The intramolecular magnetic coupling between the Cu(II) ( S = 1/2) centers is weakly antiferromagnetic ( J = −0.62 cm −1 ; g = 2.07). Reactions between 1 •MeCN and ethyl acetate (EtOAc) or ethyl benzoate (EtOBz) in DMF at ≈60 °C led to hydrolysis of carboxy esters and afforded isolation of mononuclear acetate‐ and benzoate‐bound complexes [(L 3 )‐Cu II (OAc)(OClO 3 )] ( 2 ) and [(L 3 )‐Cu II (OBz)(H 2 O)](ClO 4 ) ( 3 ), respectively. A rationale, involving monomer–dimer equilibrium, has been provided for the observed hydrolysis of carboxy esters, where controlled isotopic labeling experiments using 18 O 2 support involvement of the μ‐hydroxido group of 1 •MeCN in carboxylate formation during ester hydrolysis. A similar reaction between 1 •MeCN and bis(4‐nitrophenyl)phosphoric acid (Hbnpp) led to isolation of a 1D‐coordination polymer {[(L 3 )‐Cu II (bnpp)](ClO 4 )} n ( 4 ). Complexes 2 – 4 have also been structurally characterized.