Syntheses and crystal structures of straight or zigzag one-dimensional coordination polymers based on Cu(II) square pyramidal or Cu(I) tetrahedral coordination environments

Two coordination polymers containing copper ions, [CU(SO4)(pyz)(H2O)]n (1) and [CU2(SO4)(PYZ)(2) (H2O)(2)](n) (2) (pyz = pyrazine), have been synthesized and characterized by single-crystal X-ray analyses. Compound I was synthesized by the reaction of Cu(SO4) center dot 5H(2)O with pyz (ratio = 1:2) in H2O at room temperature. The structure of 1 consists of linear chains of [Cu(pyz)(H2O)](2+), with coordinated sulfate ions bridging the chains. Compound 2 was obtained as dark red blocks from the reaction of CU(SO4) center dot 5H(2)O and pyz (ratio = 1:2) in H2O, after heating to 181 degrees C in a Teflon autoclave for 48 h. The structure of 2 consists of zigzag chains of [Cu(pyz)(H2O)](+) with sulfate ions. Only the difference in the synthesis temperature, room temperature or 180 degrees C, determines whether Cu(II) or Cu(I) coordination polymers are formed, with the reduction of Cu(II) to Cu(l) being explained by the Gillard mechanism. (c) 2008 Elsevier Ltd. All rights reserved.