New Molecular-based quasi-2D S=1/2 Heisenberg Antiferromagnet

We report on the magnetic properties of a newly synthesized molecular-based quasi-2D S=1/2 Heisenberg antiferromagnet, Cu(pz)$_{2}$(HOpy)$_{2}$(ClO$_{4})_{2}$, where pz = pyrazine and HOpy = 2-hydroxypyridine. Powder susceptibility studies show the intralayer exchange J to be 7 K, with the ordering temperature less than 1.8 K. The compound consists of layers of Cu(II) ions bridged by pyrazine molecules into a square lattice, with the bulky HOpy molecules coordinated in the axial sites, providing exceptional isolation between layers (layer-layer distance = 12.18 {\AA}). Unlike all other members of the copper/pyrazine family of 2D antiferromagnets, no anions are coordinated to the copper sites, a factor that may influence the exchange anisotropy that can dominate the low-temperature behavior in this family. Recent results will be reported.