Magnetic interactions as a pivotal determinant in stabilizing a novel AgIIAgIIIF5 polymorph with high spin AgIII

Abstract

Based on theoretical calculations, we introduce a new AgIIAgIIIF5 monoclinic polymorph with a rare high spin AgIII. Our analysis of the experimental xray diffraction data available in the literature reveals that this polymorph was likely prepared in the past in a mixture with the triclinic form of the same compound. Theoretical calculations reproduce very well the lattice parameters of both forms. Calculations suggest that under ambient conditions, the monoclinic form is the more energetically stable phase of Ag2F5. We predict a strong one-dimensional antiferromagnetic superexchange between silver cations of different valences with superexchange constant of minus 207 meV (hybrid functional result). The polymorph with high spin AgIII owes its stability over the one with low spin AgIII, to these magnetic interactions.