catena-Poly[[[tetraaquaerbium(III)]-μ-oxalato-κ⁴O¹,O²:O^1′,O^2′] [bromidobis(pyrazine-2-carboxylato-κ²N¹,O)cuprate(II)] tetrahydrate]

Abstract

In the title heterometallic complex, {[Er(C2O4)(H2O)4][CuBr(C5H3N2O2)2]·4H2O}n, the ErIII atom is eight-coordin­ated by four O atoms from two centrosymmetric oxalate ligands and four water mol­ecules, displaying a bicapped trigonal-prismatic geometry. The oxalate ligands bridge the Er atoms into a polymeric cationic chain along [110]. The CuII atom is five-coordinated in a square-pyramidal geometry by two pyrazine-2-carboxyl­ate ligands and a Br atom, forming a discrete anion. The polymeric cations, complex anions and uncoordinated water mol­ecules are self-assembled into a three-dimensional supra­molecular network through O—H⋯N, O—H⋯O and O—H⋯Br hydrogen bonds.