Abstract: | The title coordination polymer, poly(μ4‐2‐oxidoisophthalato‐κ6O1,O2:O2,O3:O3′:O3′)(μ2‐quinoxaline‐κ2N:N′)copper(I)copper(II)], Cu2(C8H3O5)(C8H6N2)]n, contains two crystallographically distinct Cu ions, one quinoxaline (QA) unit and one 2‐oxidoisophthalate trianion (L) derived from 2‐hydroxyisophthalic acid (H3L). The CuII ion is strongly coordinated by four O atoms in a distorted square geometry, of which two belong to two phenoxide groups and the other two to carboxylate groups of two L ligands. In addition, the CuII cation interacts weakly with a symmetry‐related carboxylate O atom which belongs to the L ligand in an adjacent layer, giving a square‐pyramidal coordination geometry. The CuI ion is trigonally coordinated by two N atoms from two QA molecules and one O atom from an L carboxylate group. The CuI centres are bridged by QA ligands to give a chain along the c axis. Two CuII ions and two L ligands form a Cu2L2]2? `metallo‐ligand', which coordinates two CuI ions. Thus, the chains of CuI and QA are linked by the Cu2L2]2? metallo‐ligand to yield a two‐dimensional (6,3) sheet. These sheets are further linked by symmetry‐related carboxylate O atoms of neighbouring layers into a three‐dimensional framework. The in situ reaction from benzene‐1,2,3‐tricarboxylic acid (H3L1) to L in the present system has rarely been observed before, although a few novel in situ reactions, such as ligand oxidative coupling, hydrolysis and substitution, have been observed during the hydrothermal process. |