LOW-TEMPERATURE X-RAY-DIFFRACTION STUDIES ON [CU(4-XPZ)2]X LINEAR-CHAIN POLYMERS (WHERE X=CL, BR, CH3, H-PZ=PYRAZOLATE)

Room temperature and low-temperature (110-140 K) powder diffractograms have been obtained for the polymeric compounds [Cu(4-Xpz)2], (where X = H, CH3, Cl, and Br), and values of the unit cell parameters (orthorhombic, space group Ibam) a, b, and c have been obtained at both high and low temperatures. A single crystal X-ray diffraction study of the X = H compound at 116 K was completed and the results compared with a published study done at room temperature. The structures of these complexes involve extended chains of pyrazolate-bridged copper ions extending along the c crystallographic axis. The X-ray studies indicate little change in the c parameter with decreasing temperature and small but significant changes in the a or b parameters reflecting changes in interchain packing. This study permits some evaluation of how structural parameters are affected by these variations in interchain packing and how these variations may be affecting the magnitude of magnetic exchange in the compounds.