Mn(II) staircase structures stitched by water clusters to a 3D metal-organic open framework: X-ray structural and magnetic studies

4-Hydroxypyridine-2,6-dicarboxylic acid (chelidamic acid, cdaH<SUB>2</SUB>) reacts with Mn(OAc)<SUB>2</SUB>&#183;4H<SUB>2</SUB>O to form a 1D staircase structure with dimeric Mn(II) units connected by water clusters to form a 3D framework, {[Mn<SUB>2</SUB>(cda)<SUB>2</SUB>&#183;4H<SUB>2</SUB>O]&#183;4H<SUB>2</SUB>O}<SUB>n</SUB>, 1, in aqueous pyridine at room temperature. The compound crystallizes in the triclinic space group P with a = 9.495(3), b =10.733(5), c = 11.065(4) &#197;, &#945; = 87.42(5), &#946; = 74.14(5), &#947; = 80.07(2)&#176; , U = 1068.5(9) &#197;<SUP>3</SUP>, Z = 2, &#961;<SUB>calcd</SUB> = 1.915 g cm<SUP>-3</SUP>, T = 100 K, &#956; = 1.28 mm<SUP>-1</SUP>, R<SUB>1</SUB> = 0.0453 (I &gt; 2&#963;(I)), wR<SUB>2</SUB> = 0.1046, GOOF = 1.282. Upon removal of the water molecules by heating, the 3D structure breaks down. Thermogravimetric analysis, infrared, X-ray powder diffraction studies, and X-ray crystallography were performed to characterize this compound. Since the coordination polymer has diaqua-bridged Mn(II) centers, it was subjected to variable-temperature magnetic studies