The reaction of N,N′-dimethyl-N,N′-ethylenebis (5-bromo-3-formyl-2-hydroxybenzylaminato)copper(II) with ethylenediamine in aqueous DMF with excess perchloric acid resulted in the [2:2] cyclic condensation of the constituents, providing the dinuclear CuII complex [Cu2(H2R)](ClO4)2. It crystallizes in the monoclinic space group P21/c, with a = 19.603(3) Å, b = 13.370(2) Å, c = 21.072(3) Å, β = 98.87(1)° V = 5456(1) Å3, and Z = 4. The ligand R4- has two N(amine)2O2 and two N(imine)2O2 metal-binding sites sharing two phenolic oxygens, and [Cu2(H2R)](ClO4)2 has the two CuII ions in the N(imine)2O2 sites and two protons in the N(amine)2O2 sites. [Cu2(H2R)](ClO4)2 was converted by neutralization into [Cu2(R)], from which mixed-metal CuII2MII2 complexes [Cu2M2(R)Cl4] (M = CoII, NiII, ZnII) were derived. [Cu2Co2 (R)Cl4]·2CHCl3·H2O crystallizes in the monoclinic space group C2/c, with a = 32.514(3) Å, b = 12.246(3) Å, c = 19.827(2) Å, β = 126.082(1)° V = 6380(1) Å3, and Z = 4. [Cu2Zn2(R)Cl4] ·2CHCl3·H2O crystallizes in the monoclinic space group C2/c, with a = 32.53(1) Å, b = 12.242(2) Å, c = 19.729(9) Å, β = 126.03(3)°, V = 6354(4) Å3, and Z = 4. The two complexes are isotructural and have a dimer-of-dimers structure with two separated CuIIMII units. In each dinuclear unit, the CuII is bound to the N(imine)2O2 site and the MII is bonded to a phenolic oxygen and two nitrogens of the N(amine)2O2 site. The CuII and MII ions are bridged by a phenolic oxygen and an exogenous chloride ion. The CuII2NiII2 complex has a defect double-cubane structure. Cryomagnetic studies for the CuII2CoII2 complex indicate an antiferromagnetic spin-exchange interaction within each dinuclear CuIICoII unit (J = -9.5 cm-1 based on H = -2JSCuSCo). The CuII2NiII2 complex shows a weak antiferromagnetic interaction between the adjacent CuII and NiII ions (-3.5 cm-1) and a weak ferromagnetic interaction between the two NiII ions (+2.0 cm-1.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Inorganic Chemistry