The crystal structure of Rb2Ru2O7.H2O was determined by three-dimensional electron diffraction from the individual crystallites of a solid-state powder product. Rb2Ru2O7.H2O crystallizes in space group \textit{C}2/\textit{c} (a=7.841(3) \AA, b=12.500(3) \AA, c=8.392(2) \AA, β=93.57(4)∘, Z=4). The structure contains infinite chains that run normal to the (101) plane and consist of alternating RuO6 octahedra and square-pyramidal RuO5 units connected via shared O-O edges. Magnetic properties were measured on the bulk powder, showing a diamagnetic baseline from 300 to 60 K with a small Curie tail below 55 K. The magnetic moment, calculated from the 1.8 K isotherm, saturates at M=4.4×10−3μBRu−1, much less than would be expected for S=1 ruthenium. Bond-valence-sum analysis indicates high-valent Ru, and the near-diamagnetic response is consistent with the edge-sharing Ru-Ru motif, where weak direct Ru-Ru overlap yields a local singlet.
@article{arxiv.2601.13154,
title = {Magnetism and 3D Electron Diffraction Solution of Hydrated Rubidium-Ruthenium Oxide Rb$_2$Ru$_2$O$_7$.H$_2$O},
author = {Krystof Chrappova and Jeremiah P. Tidey and Christopher Bell and Simon R. Hall},
journal= {arXiv preprint arXiv:2601.13154},
year = {2026}
}