Crystal structure of poly[bis­(μ-2-bromo­pyrazine)­tetra-μ(2)-cyanido-dicopper(I)iron(II)]: a bimetallic metal-organic framework

In the title metal-organic framework, [Fe(C(4)H(3)BrN(2))(2){Cu(CN)(2)}(2)](n), the Fe(II) cation is located on an inversion center and has a slightly elongated octa­hedral coordination environment [FeN(6)], ligated by two pyrazine N atoms of symmetry-related bridging 2-bromo­pyrazine mol­ecules in the axial positions and by four N atoms of pairs of symmetry-related cyanido groups in the equatorial positions. The Cu(I) center has a fourfold coordination environment [CuC(3)N], with an almost perfect trigonal–pyramidal geometry, formed by three cyanido C atoms and an N atom of a bridging 2-bromo­pyrazine mol­ecule. Copper(I) centers related by a twofold rotation axis are bridged by two carbon atoms from a pair of μ-CN groups, resulting in Cu(2)(CN)(2) units. Each Cu(2)(CN)(2) unit is linked to six Fe(II) cations via a pair of linear CN units, the pair of μ-CN groups and two bridging 2-bromo­pyrazine ligands, resulting in the formation of a metal–organic framework, which is additionally stabilized by the short Cu⋯Cu contacts of 2.4450 (7) Å.