| Binuclear Copper(II) Complexes with $N_4O_3$ Coordinating Heptadentate Ligand: Synthesis, Structure, Magnetic Properties, Density-Functional Theory Study, and Catecholase Activity (2008) | |||||||||
Abstract | |||||||||
| The $N_4O_3$ coordinating heptadentate ligand afforded binuclear complex $[Cu_2(H_2L)(\mu-OH)](ClO_4)_2$ (1) and $[Cu_2(L)(H_2O)_2]PF_6$ (2). In complex 1, two copper ions are held together by \mu-phenoxo and \mu-hydroxo bridges, whereas in complex 2, the copper centers are connected only by a \mu-phenoxo bridge. In 1, both the Cu(II) centers have square pyramidal geometry (\tau = 0.01−0.205), whereas in the case of 2, one Cu(II) center has square pyramidal (\tau = 0.2517) and other one has square based pyramidal distorted trigonal bipyramidal (\tau = 0.54) geometry. Complexes 1 and 2 show an strong intramolecular and very weak antiferromagnetic interaction, respectively. Density-functional theory calculations were performed to establish the magneto structural correlation between the two paramagnetic copper(II) centers. Both of the complexes display a couple of one-electron reductive responses near −0.80 and −1.10 V. The complexes show significant catalytic activity at pH 8.5 on the oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) to 3,5-di-tert-butylquinone (3,5-DTBQ), and the activity measured in terms of kcat = 29−37 h−1. | |||||||||
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