LOW-TEMPERATURE X-RAY STRUCTURE DETERMINATIONS, AND SINGLE-CRYSTAL MAGNETIC-SUSCEPTIBILITY AND EPR STUDIES ON (3-CHLOROANILINIUM)8CUCL6!CL4

A recent X-ray diffraction study has shown that (3-chloro-anilinium)8 CuCl6!Cl4 contains compressed CUC16!4-octahedra. Low temperature stud ies reported here do not obviate such a conclusion, and so, questions concerning disorder and dynamics still remain. Down to 110 K, the CUC l6!4-ions are arranged in a quasi-linear chain. SQUID-based temperatur e-dependent magnetic susceptibility data exhibit a maximum near 17 K. The Bonner-Fisher model yields an antiferromagnetic Heisenberg exchang e of J = -9.3 cm-1. Magnetic field-dependent susceptibility measuremen ts on single crystals with the chain-axis aligned parallel to the fiel d, show a marked field dependence below 9 K and suggest weak ferromagn etism due to spin canting. Single crystal EPR measurements at room tem perature yield g(parallel-to) = 2.035 and a single g(perpendicular-to) 2.202; at 4 K, g(parallel-to) = 2.041 with g(perpendicular-to 1) = 2. 200 and g(perpendicular-to 2) = 2.168. Line widths in all orientations at 4 K are very narrow, ranging from 0.5 to 2.0 mT.