Magnetic characterization of the frustrated three-leg ladder compound   [(CuCl2tachH)3Cl]Cl2
  We report the magnetic features of a new one-dimensional stack of antiferromagnetically coupled equilateral copper(II) triangles. High-field magnetization measurements show that the interaction between the copper triangles is of the same order of magnitude as the intra-triangle exchange although only coupled via hydrogen bonds. The infinite chain turns out to be an interesting example of a frustrated cylindrical three-leg ladder with competing intra- and inter-triangle interactions. We demonstrate that the ground state is a spin singlet which is gaped from the triplet excitation. 
J. Schnack, Hiroyuki Nojiri, P. Koegerler, Geoffrey J. T. Cooper,   Leroy Cronin