Inorganic Chemistry, Vol.45, No.2, 505-507, 2006
Unique asymmetric (Cu-4(II)) double-stranded helicate from a hexadentate piperazine-based ligand: Ligand conformation isomerism upon coordination
In methanol, the reaction of Cu(ClO4)(2)center dot 6H(2)O and a sterically constrained piperazine imine phenol ligand (H2L), in the presence of NEt3, affords a novel tetranuclear copper(II) complex of formula [Cu-4(II)(mu(3)-L)(2)(mu-OH)(2)(H2O)(2)](ClO4)(2)center dot H2O (1). The X-ray structure of this complex shows an elongated Cu-4 quasi-tetrahedron coordinated to two hexadentate chair-(e, a)-mu(3)-piperazine bridging ligands. Variable-temperature magnetic studies show an S-t = 0 spin ground state resulting from antiferromagnetic interactions between Cull ions within the complex.