Magnetostructural correlations and catecholase-like activities of μ-alkoxo-μ-carboxylato double bridged dinuclear and tetranuclear copper(II) complexes

Synthesis, structure, magnetism, and hydrolase and catecholase activity of a new trinuclear copper(II) complex

“…On the other hand, in 1, Cu3 lies in a slightly distorted square planar geometry as can be observed from the bond angles around this center and thus the unpaired electron is also in the d of the Cu1 and Cu2 centers, leading to weak ferromagnetic coupling (J 1,3 = J 2,3 ffi + 4.0 cm À1 ) between the Cu3 and Cu1/Cu2 centers. For comparison, the weak antiferromagnetism (J = À1.0 cm À1 ) between Cu(1) and Cu(2) falls in the range of J values observed for many Cu(l-alkoxo)(l-Acetate)Cu complexes reported in the literature[22,23]. On the other hand, the weak ferromagnetic exchange (J 1,3 = J 2,3 ffi + 4.0 cm À1 ) between the Cu(3) and Cu(1)/Cu(2) centers are in agreement with the ferromagnetic coupling observed for open type dinuclear Cu(II) com-…”

A dicopper complex with distant metal centers. Structure, magnetic properties, electrochemistry and catecholase activity

“…7.4 Å , with virtually no steric possibility to approach each other enough so that both Cu atoms can bind to a single catecholate unit, as required in the most widely accepted mechanism [8]. However, the observed catalytic activity is similar or even superior to several dinuclear complexes described in the literature with Cu-Cu distances close to 3 Å [8,10,11,20,[22][23][24][25][26][27]. An remarkable feature is that in spite of this rather large separation between the two copper atoms, its frozen solution EPR spectrum suggests they are magnetically coupled.…”

Characterization of a Dinuclear Copper(II) Complex and Its Fleeting Mixed‐Valent Copper(II)/Copper(III) Counterpart

“…In the solid state, the temperature dependence of the product of the molar susceptibility and temperature, χΤ , shows a typical profile of ferromagnetic coupling interactions (Figure ). The rapid decrease of χΤ below 20 K may be due to intermolecular antiferromagnetic interactions . The data could be fitted by using a model for two coupled spins ( S =1/2) described by the spin‐Hamiltonian H =− J S 1 S 2 and with the use of an additional mean field approximation to reproduce intermolecular interactions.…”

“…Parameter optimization yielded a coupling constant of J= 53.8 cm −1 with g =2.20. Other μ‐alkoxo‐μ‐monocarboxylato dinuclear copper(II) complexes have been structurally and magnetically studied in the literature, allowing the establishment of magnetostructural correlations . From these studies, a Cu1‐O1‐Cu2 angle ( θ ) greater than 116.5°, as it is the case in 1 (127.54°), should lead to an antiferromagnetic coupling, whereas ferromagnetism appears for smaller values of θ .…”