Na2AgF4: 1D antiferromagnet with unusually short Ag2+⋯Ag2+ separation
Disodium tetrafluoroargentate(II) (Na2AgF4) has been synthesized by the thermal decomposition of NaAg(III)F4 in the presence of NaF. This novel synthetic pathway yielded a high-purity product which enabled determination of the crystal structure and magnetic properties of this compound. The crystal structure of Na2AgF4 contains infinite [AgF2+4/2]2− chains, in analogy to β-K2AgF4, but with a different packing of chains. The unusually short Ag2+⋯Ag2+ contact of 3.342 Å within the chain is the shortest Ag2+⋯Ag2+ distance among all structurally characterized compounds of divalent silver. This structural feature is responsible for the 1D antiferromagnetic properties of Na2AgF4 as determined from powder magnetic susceptibility measurements. These findings are rationalized with the aid of calculations of magnetic coupling constants within the framework of the Density Functional Theory including on-site Coulomb repulsion (DFT+U).