catena-Poly[[tetra­kis­(hexa­methyl­phospho­ramide-κO)bis­(nitrato-κ²O,O′)erbium(III)] [silver(I)-di-μ-sulfido-tungstate(VI)-di-μ-sulfido]]

In the title compound, {[Er(NO₃)₂(C₆H₁₈N₃OP)₄][AgWS₄]}_n, the polymeric anionic chain {[AgWS₄]⁻}_n extends along [001]. The Er^III atom in the cation is coordinated by eight O atoms from two bidentate nitrate anions and four hexa­methyl­phospho­ramide ligands in a distorted square-anti­prismatic geometry. Together with the two nitrate ligands, the cation is monovalent, which leads to the anionic chain having a [WS₄Ag] repeat unit. The polymeric anionic chain has a distorted linear configuration, with W—Ag—W and Ag—W—Ag angles of 161.37 (2) and 153.548 (12)°, respectively. The title complex is isotypic with the Y, Yb, Eu, Nd, La, Dy, Sm, Lu and Tb analogues.