The twofold superstructure of titanium(III) oxybromide at T = 17.5 K

The low‐temperature (T = 17.5 K) structure of titanium(III) oxybromide, TiOBr, is reported as a twofold superstructure of the crystal structure at room temperature. Weak superlattice reflections were measured with synchrotron radiation X‐rays and were analyzed by structure refinements employing superspace techniques. Both the low‐temperature and the room‐temperature structures of TiOBr are isostructural with the corresponding structures of TiOCl. The results indicate that at low temperatures TiOBr is in a spin‐Peierls state, similar to that of TiOCl, but with the modulations and relevant inter­actions smaller than in the latter compound.