Structure and magnetic susceptibility of (PhCH2NEt3)2Cu2Br6: Unprecedented similarity to the Haldane state with potential competing interactions

A new binuclear copper(II) compound with mono-atomic bridging ligands has been studied within this work. Each copper atom in the (μ-bromo)-bridged complex adopts unusually intermediate geometry between square planar and tetrahedral. Magnetic characterization of this new complex shows it to be a candidate for a rare quantum regime where an S = ½ magnetic ladder may cross over into an S = 1 Haldane system. This may occur when an S = ½ half magnetic ladder exhibits ferromagnetic interactions across its rungs and antiferromagnetic interactions along its rails. To our knowledge, this compound is the first example of this theoretically predicted system.151