A three-dimensional mixed-valence CuII/CuI coordination polymer constructed from biphenyl-3,4′,5-tricarboxylate and 1,4-bis(1 H-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-κ⁴ O³: O^3′: O^4′: O⁵)tris[μ₂-1,4-bis(1 H-imidazol-1-yl)benzene-κ² N³: N^3′]dicopper(II)dicopper(I)], [Cu^II₂Cu^I₂(C₁₅H₇O₆)₂(C₁₂H₁₀N₄)₃(H₂O)₂] _n, was crystallized from a mixture of biphenyl-3,4′,5-tricarboxylic acid (H₃bpt), 1,4-bis(1 H-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 bpt³⁻ 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 bpt³⁻ ligand and two N atoms from two 1,4-bib ligands. The Cu^II atoms are extended by bpt³⁻ 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] direction. In addition, the completely deprotonated μ₄-η¹:η¹:η¹:η¹ bpt³⁻ ligands bridge one Cu^I and three Cu^II cations along the a (or [100]) direction to form a three-dimensional framework with a (10³)₂(10)₂(4².6.10².12)₂(4².6.8².10)₂(8) topology via a 2,2,3,4,4-connected net. An investigation of the magnetic properties indicated a very weak ferromagnetic behaviour. [ABSTRACT FROM AUTHOR]