Crystal structure of a low-spin poly[di-l3-cyanido-di-l2-cyanido-bis(l2-2-ethylpyrazine)dicopper(I)-iron(II)]

Abstract

In the title metal-organic framework, [Fe(C6H8N2)2{Cu(CN)2}2]n, the low-spin FeII ion lies at an inversion centre and displays an elongated octahedral [FeN6] coordination environment. The axial positions are occupied by two symmetry-related bridging 2-ethylpyrazine ligands, while the equatorial positions are occupied by four N atoms of two pairs of symmetry-related cyanide groups. The CuI centre is coordinated by three cyanide carbon atoms and one N atom of a bridging 2-ethylpyrazine molecule, which form a tetrahedral coordination environment. Two neighbouring Cu atoms have a short Cu Cu contact [2.4662 (7) Å] and their coordination tetrahedra are connected through a common edge between two C atoms of cyanide groups. Each Cu2(CN)2 unit, formed by two neighbouring Cu atoms bridged by two carbons from a pair of -CN groups, is connected to six FeII centres via two bridging 2-ethylpyrazine molecules and four cyanide groups, resulting in the formation of a polymeric three-dimensional metal-organic coordination framework.