A Novel μ₄-Oxo Bridged Copper Tetrahedron Derived by Self-Assembly: First Example of Double Helical Bis(Tridentate) Coordination of a Hexadentate Amine Phenol Ligand

In methanol, the reaction of Cu(ClO4)2·6H2O and the hexadentate amine phenol ligand (H2bahped) in the presence of triethylamine affords a tetranuclear copper(II) complex having the formula [Cu4(μ4-O)(bahped)2](ClO4)2. The X-ray structure of this complex shows a tetrahedral central {CuII4(μ4-O)}unit coordinated to two hexadentate bridging (via the central ethylenediamine part) ligands. The compound is the first example of a μ4-oxo tetranuclear copper(II) complex without any bridging ligand along the six tetrahedral edges. Variable-temperature magnetic data clearly show an St = 0 spin ground state for antiferromagnetic interactions between four 2B2 copper(II) ions in a dimer of dimers.