The copper(II) complex Cu₂L(OAc)(H₂O)_3.5, 1·3.5H₂O was obtained and its reactivity in a basic medium investigated. Complex 1·3.5H₂O shows different reaction patterns in air and in an inert atmosphere. Accordingly, interaction of 1·3.5H₂O with Me₄NOH·5H₂O in methanol–acetonitrile in air yields the hydroxide complex Cu₂L(OH)(H₂O)_1.125, 2·1.125H₂O while Cu₂L(OMe)(MeOH)_0.5(H₂O), 3·0.5MeOH·H₂O is isolated under an argon atmosphere. The products 1–3 were fully characterised and single crystals of {[Cu₂L(OAc)]·MeCN·3.5H₂O}₂, 1·MeCN·3.5H₂O, {[Cu₂L(OH)]·MeCN·1.125H₂O}₂, 2·MeCN·1.125H₂O and [Cu₂L(OMe)]·0.5MeOH·H₂O, 3·0.5MeOH·H₂O solved. The single X-ray study shows that 1–3 are dinuclear complexes with an endogenous phenol oxygen and an exogenous O-bridge. Magnetic characterisation of the three dinuclear complexes was performed, showing an apparent anomalous intramolecular ferromagnetic coupling between the metal atoms in all cases.