Poly[[[μ- trans -1,2-bis-(pyridin-4-yl)ethene-κ 2 N : N ']-μ-iodido-copper(I)]- trans -1,2-bis-(pyridin-4-yl)ethene (1/0.25)].

The title compound, {[CuI(bpe)]·0.25(bpe)} n , was synthesized similarly to (CuI) 2 (bpe) [Neal et al. (2019 ▸). IUCrData , 4 , x190122] with red crystals grown from aceto-nitrile solutions of CuI and the bpe ligand [bpe = 1,2-bis-(pyridin-4-yl)ethene, C 12 H 10 N 2 ]. The structure of the title compound is a type 1 complex in the Graham nomenclature [Graham et al. (2000 ▸). Inorg. Chem . 39 , 5121-5132], having rhombic dimers of Cu 2 I 2 that are bridged by two bpe ligands, to form oligomeric ribbons arranged as stairsteps. The step height is 2.8072 (11) Å, which is the Cu-I i distance of the dimer [symmetry code (i): 1 -  x , 2 -  y , 1 -  z ]. The resulting polymer displays a two-dimensional honeycomb framework along the (01) plane, and disordered free bpe mol-ecules fill the voids in the crystal.