A Novel Three-dimensional Mn(II) Coordination Polymer Constructed from Biphenyl-3,3′,5,5′-tetracarboxylic Acid and Water

The title Mn(II) coordination polymer, poly{[heptaaqua-(mu(4)-bi-phenyl-3,3',5,5'-tetracarboxylate)- bimanganese(II)] pentahydrate}, [Mn-2(bpta)(H2O)(7)](n)center dot 5nH(2)O (I), is crystallized from a mixture of biphenyl-3,3',5,5'-tetracarboxylic acid (H(4)bpta) and MnCl2 center dot 4H(2)O in water-ethanol under room temperature. Its asymmetric unit consists of one and two halves of crystallographically independent Mn(II) cations, one fully deprotonated H(4)bpta ligand, seven coordinated water molecules and five solvent water as guest molecules. In I, each Mn(II) atom is octahedrally coordinated by six oxygen atoms from bpta(4-) anions and coordinated water molecules. In the Mn(II) cations, one half Mn(II) ion of them located at a 2-fold axis generating a trinuclear [Mn-3(H2O)(2)(R-COO)(2)] linker by mu(1,1)-O(water) and mu(1,3)-O,O'(carboxylate) bridges and another half Mn(II) ion with an inversion is a mononuclear linker. These neighbouring trinuclear and mononuclear Mn(II) cations are linked together by biphenyl-3,3',5,5'-tetracarboxylates to form a three-dimensional framework with a (4(2).8(4)) topology of a (4,4)-connected net, in which the positions of the trinuclear [Mn-3(H2O)(2)(R-COO)(2)] linker as a 4-connector linking four bpta(4-) ligands in I reproduce an eagle-shaped arrangement. The polymeric structure exhibits a water channel with an accessible void of 797.1 angstrom(3), amounting to 15.7% of the total unit-cell volume. Each of the cavities in the network is occupied by solvent water molecules.