Reproducing Historic Inorganic Compounds: Reference Materials for Identifying Compounds in the Clemens‐Winkler Collection (Part 3)

The Clemens‐Winkler collection is a significant 19 ^th ‐century archive of inorganic chemical specimens, offering insights into the scientific practices of its era. As part of a digitization project, this study uses nondestructive analytical techniques—synchrotron‐based X‐ray diffraction (XRD) and X‐ray fluorescence (XRF) at the P21.2 beamline of PETRA III, as well as laboratory Raman spectroscopy and handheld XRF—to characterize historical samples without opening or damaging their sealed containers. In two related articles, we report results for objects whose identities were confirmed and whose syntheses could be reconstructed. A key challenge in this study was the lack of modern reference data for several historical compounds. We therefore reproduced these substances using 19 ^th ‐century preparative methods to generate authentic reference materials. Four new single‐crystal X‐ray structures were determined. Our results also demonstrate that laboratory Raman spectroscopy can identify components, including inorganic compounds, inside sealed historic ampoules. The study compares the original specimens with the newly synthesized reference compounds, including rubidium(I) chlorobromoiodide, ammonium hexabromidotellurate(IV), ammonium hexachloridotellurate(IV), and several tetracyandioplatinates(II) of barium, calcium, magnesium, yttrium, praseodymium, neodymium, potassium, and sodium.