Copper coordination polymers containing the ligand tetraminomethylpyrazine(tampyz): structure determination from laboratory X-ray powder diffractiondata

X-ray powder diffraction data have been collected on two different micro-cr ystalline compounds in order to determine their three-dimensional structure and to refine the structures by Rietveld methods. The first sample is a mi xed phase system containing two different compounds, ([Cu2Cl4(tampyz)] (H2O )(2.2))(n) (1) and [Cu2Cl4(tampyz)] (2), where tampyz 2, 3, 5, 6-tetrakis ( aminomethyl) pyrazine. The structure of I was first determined by single cr ystal X-ray analysis and found to be a ladder type coordination polymer 1. After some time, the crystals loose the water molecules of crystallization and a microcrysstalline powder was formed. The X-ray powder diffraction pat tern, recorded for this same sample, shows a mixture of two compounds, 1 an d 2. In 2, a binuclear complex, the cooper atoms which are bridged by the l igand tampyz, have a distirted square pyramidal coordination sphere in cont rast to 1, where the copper atoms can best described as square bipyramidal. Rietveld refinement was carried out for both phases in a single X-ray powd er pattern (ratio 1:2 = 1:1). The structure of complex 3, ([Cu2Cl3 (tampyz) ](2) [Cu2Cl4(tampyz)] (H2O)(2) (ClO4)(2))(n) was solved ab initio from X-ra y powder diffraction data. Here, a one-dimensional coordination polymer con taining [Cu2Cl3(tampyz)] units is combined with the binuclear complex [Cu2C l4(tampyz)]. In addition, one perchlorate anion and one water molecule were found in the crystal structure.