One-dimensional Cu(II) coordination polymers containing C2h-symmetric 1,1':4',1''-terphenyl-3,3'-dicarboxylate linkers

A three-dimensional mixed-valence Cu(II)/Cu(I) coordination polymer constructed from biphenyl-3,4',5-tricarboxylate and 1,4-bis(1H-imidazol-1-yl)benzene ligands

Coordination polymers (CPs) built by coordination bonds between metal ions/clusters and multidentate organic ligands exhibit fascinating structural topologies and potential applications as functional solid materials. The title coordination polymer, poly[diaquabis(μ4-biphenyl-3,4',5-tricarboxylato-κ(4)O(3):O(3'):O(4'):O(5))tris[μ2-1,4-bis(1H-imidazol-1-yl)benzene-κ(2)N(3):N(3')]dicopper(II)dicopper(I)], [Cu(II)2Cu(I)2(C15H7O6)2(C12H10N4)3(H2O)2]n, was crystallized from a mixture of biphenyl-3,4',5-tricarboxylic acid (H3bpt), 1,4-bis(1H-imidazol-1-yl)benzene (1,4-bib) and copper(II) chloride in a water-CH3CN mixture under solvothermal reaction conditions. The asymmetric unit consists of two crystallographically independent Cu atoms, one of which is Cu(II), while the other has been reduced to the Cu(I) ion. The Cu(II) centre is pentacoordinated by three O atoms from three bpt(3-) ligands, one N atom from a 1,4-bib ligand and one O atom from a coordinated water molecule, and the coordination geometry can be described as distorted trigonal bipyramidal. The Cu(I) atom exhibits a T-shaped geometry (CuN2O) coordinated by one O atom from a bpt(3-) ligand and two N atoms from two 1,4-bib ligands. The Cu(II) atoms are extended by bpt(3-) and 1,4-bib linkers to generate a two-dimensional network, while the Cu(I) atoms are linked by 1,4-bib ligands, forming one-dimensional chains along the [20-1] direction. In addition, the completely deprotonated μ4-η(1):η(1):η(1):η(1) bpt(3-) ligands bridge one Cu(I) and three Cu(II) cations along the a (or [100]) direction to form a three-dimensional framework with a (10(3))2(10)2(4(2).6.10(2).12)2(4(2).6.8(2).10)2(8) topology via a 2,2,3,4,4-connected net. An investigation of the magnetic properties indicated a very weak ferromagnetic behaviour.

Synthesis and crystal structure of a two-dimensional sodium coordination polymer of 4,4'-(diazenediyl)bis(1H-1,2,4-triazol-5-one)

The crystal engineering of coordination polymers has aroused interest due to their structural versatility, unique properties and applications in different areas of science. The selection of appropriate ligands as building blocks is critical in order to afford a range of topologies. Alkali metal cations are known for their mainly ionic chemistry in aqueous media. Their coordination number varies depending on the size of the binding partners, and on the electrostatic interaction between the ligands and the metal ions. The two-dimensional coordination polymer poly[tetra-μ-aqua-[μ4-4,4'-(diazenediyl)bis(5-oxo-1H-1,2,4-triazolido)]disodium(I)], [Na2(C4H2N8O2)(H2O)4]n, (I), was synthesized from 4-amino-1H-1,2,4-triazol-5(4H)-one (ATO) and its single-crystal structure determined. The mid-point of the imino N=N bond of the 4,4'-(diazenediyl)bis(5-oxo-1H-1,2,4-triazolide) (ZTO(2-)) ligand is located on an inversion centre. The asymmetric unit consists of one Na(+) cation, half a bridging ZTO(2-) ligand and two bridging water ligands. Each Na(+) cation is coordinated in a trigonal antiprismatic fashion by six O atoms, i.e. two from two ZTO(2-) ligands and the remaining four from bridging water ligands. The Na(+) cation is located near a glide plane, thus the two bridging O atoms from the two coordinating ZTO(2-) ligands are on adjacent apices of the trigonal antiprism, rather than being in an anti configuration. All water and ZTO(2-) ligands act as bridging ligands between metal centres. Each Na(+) metal centre is bridged to a neigbouring Na(+) cation by two water molecules to give a one-dimensional [Na(H2O)2]n chain. The organic ZTO(2-) ligand, an O atom of which also bridges the same pair of Na(+) cations, then crosslinks these [Na(H2O)2]n chains to form two-dimensional sheets. The two-dimensional sheets are further connected by intermolecular hydrogen bonds, giving rise to a stabile hydrogen-bonded network.