An unprecedented copper(I,II)–octacyanotungstate(V) 2-D network: crystal structure and magnetism of [CuII(tren)]{CuI[WV(CN)8]}·1.5H2O

A novel two-dimensional cyanide-bridged polymer [CuII(tren)]{CuI[WV(CN)8]}·1.5H2O (tren = tris(2-aminoethyl) amine) formed via the simultaneous in situ metal–ligand redox reaction of [Cu(tren)(OH2)]^2+ and self-assembly with [WV(CN)8]^3– consists of a {CuI[WV(CN)8]} square grid built of CuI centres of tetrahedral geometry coordinatively saturated by CN bridges and [WV(CN)8]^3– capped by [CuII(tren)]^2+ moieties; it exhibits ferromagnetic coupling J1=+5.8(1) cm^–1 within the CuII–WV dinuclear subunits and weak antiferromagnetic coupling J2=–0.03(1) cm^–1 between them through diamagnetic CuI spacers.