 Barium platinocyanide

Barium platinocyanide is a salt of the tetracyanoplatinate(II) anion, commonly encountered as a hydrate. Its structure contains coordinated cyanide groups around platinum rather than free cyanide ions alone.

Its visible fluorescence under irradiation made it useful as a screen in the Röntgen X-ray discovery experiment. The screen converts otherwise invisible incident radiation into an optical signal.