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

TL;DR

This paper introduces a new monoclinic AgIIAgIIIF5 polymorph with high spin AgIII, showing magnetic interactions are key to its stability, supported by theoretical calculations matching experimental data.

Contribution

It presents the first theoretical prediction and analysis of a high spin AgIII polymorph stabilized by magnetic interactions, supported by lattice and magnetic property calculations.

Findings

The monoclinic form is more stable than the triclinic form at ambient conditions.

Strong antiferromagnetic superexchange exists between silver cations.

Magnetic interactions stabilize the high spin AgIII polymorph.

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.