Binuclear Copper(II) Complexes with Robsori-Type Ligands. Synthesis,characterization, crystal structure,and magnetic properties

Three binuclear copper(II) complexes, [Cu₂(μ-L)(μ-N₃)](ClO₄)2′ 1-5 EtOH (1), [Cu₂(μ-L)(μ-MeO)(ClO₄)]-ClO₄ - EtOH ( 2 ) and [Cu₂(μ-L)(μ-C₃H₃N₂)](ClO₄)₂ · 2H₂O, ( 3 ) where L is the pentadentale bridging ligand derived from 5-(tert-butyl)-2-hydroxybenzene-1, 3-dicarbaldehyde bis(benzoylhydrazone) ( HL ) were synthesized and characterized. The crystal-structure determination of complex 2 provided the following crystal data: monoclinic, space group P2₁}/a, a = 11.412(2), b = 24.509(4), c = 14.833(4) Å, β = 104.41(2)°, K = 4018(3) ų, Z = 4. The structure shows that the Cu^II ions are bridged by the endogenous phenolato O-atom and by an exogenous bridge CH₃O^?. The analysis of variable-temperature magnetic susceptibility data (4-300 K.) indicates that there is an antiferromagnetic interaction between the Cu^II ions in these complexes with an exchange parameter (2J) of ?119.1 cm^?1 for complex 1 and ?361.8 cm^?1 for complex 3 . The effect of some exogenous bridging ligands on magnetic coupling for this type of complex is suggested.