Novel 1D Cu(I) coordination polymers formed by the combination of Cu(I) halides and 4-(2-pyridyl)pyrimidine

Three novel 1D Cu(I) coordination polymers [Cu4X4(pprd)(2)](n) (X = Cl(1), Br(2) and I(3): pprd = 4-(2-pyridyl)pyrimidine) were systematically synthesized by Cu(I) halides and the pprd ligand, and they have been characterized by X-ray, IR, and TG-DTA analyses. The molecular structure of complex 1 essentially resembles to that of complex 2. In complexes 1 and 2, four Cu(I) atoms are bridged by four Cl or Br anions to form an eight-membered Cu4X4 framework in the twist-chair form. Furthermore, the Cu4X4 frameworks are coordinated by the chelate and bridging sites of two pprd ligands to form a unique 1D two-stepped Cu(I) coordination polymer, in which two stairs are formed by the Cu4X4 core and two heteroaromatic planes of pprd. In the crystal packing structures, it is interesting that two heteroaromatic planes of pprd are stacking along the b-axis for complex 1 and the a-axis for complex 2. In contrast, four Cu(I) atoms in complex 3 are bridged by four I atoms to form a Cu4I4 stepped cubane tetramer. Additionally, the Cu4I4 stepped cubane cores are linked by the chelate and bridging sites of two pprd ligands to form an infinite 1D zigzag-chain Cu(l) coordination polymer. The thermal decomposition behaviors for Cu(I)-X/pprd complexes 1, 2 and 3 were determined by thermogravimetric analysis (TG-DTA). Although the thermal decomposition behaviors of complex 1 were unidentified, those of complexes 2 and 3 were assigned. The mass loss at the first stage of thermal decomposition for polymeric [Cu4X4(pprd)(2)](n) was identical to the formation of oligomeric [Cu4X4(pprd)] by the elimination of one pprd molecule. The mass loss at the next stage was decided to the formation of Cu4X4 by the elimination of another pprd molecule. (C) 2010 Elsevier Ltd. All rights reserved.