New CuSO4-related high-temperature polymorph of AgIISO4

TL;DR

This paper reports the discovery of a new high-temperature polymorph of AgSO4 with a monoclinic structure similar to CuSO4, characterized by strong antiferromagnetic interactions, expanding understanding of silver(II) compounds.

Contribution

The study identifies and characterizes a novel AgSO4 polymorph (eta) with structural and magnetic properties distinct from known forms, using experimental and theoretical methods.

Findings

New monoclinic  polymorph of AgSO4 identified.

Structural similarity between AgSO4  and CuSO4.

Strong antiferromagnetic interactions along the unit cell diagonal.

Abstract

Silver(II) compounds exhibit powerful oxidizing properties and strong magnetic superexchange. AgSO4 is a rare fluorine-free salt of Ag(II) which found some application in organic chemistry. Here, we report a discovery of a new AgSO4 polymorph (\b{eta}). The distinct nature of the two polytypes of AgSO4 is established using powder x-ray diffraction, vibrational spectroscopy and theoretical calculations. The \b{eta} polymorph crystallizes in the monoclinic system (P21/n) and shows structural similarities with CuSO4. DFT calculations indicate very small differences in the energy of the two polymorphs AgSO4, but the relative stability of the \b{eta} polymorph should increase with temperature. The monoclinic distortion of the orthorhombic CuSO4 prototype originates from an unprecedented strong antiferromagnetic interaction between Ag sites along the unit cell diagonal.