Copper Phenazine Dichloride, a S=1/2 Heisenberg Antiferromagnetic Chain

Low-dimensional antiferromagnets provide good testing grounds for predictions of cooperative quantum behavior. S=1/2 copper ions bridged by organic ligands such as pyrazine form antiferromagnetic chains with exchange strengths weak enough to be overcome by available magnetic fields. [1] Phenazine (Phz) (C$_{12}$H$_{8}$N$_{2})$ is similar to pyrazine in its ability to form magnetic chains but has a different electronic structure resulting in different exchange strengths. We report on the synthesis, crystal structure, magnetic susceptibility, and high field magnetization of Cu(Phz)Cl$_{2}$. Its behavior can be described as that of a Heisenberg antiferromagnetic chain with an exchange constant $\vert $J$\vert $/k$_{B}$ = 33 K. The exchange strengths of chains with pyrazine, quinoxaline, and phenazine will be compared. [1] M. B. Stone et al, \textit{Physical Review Letters} \textbf {91}, 037205 (2003).