Assertion: metal's compound | /r/HasProperty | rare
Facets:
Source sentences:
text: Compounds of chromium(V) are rather rare; the oxidation state +5 is only realized in few compounds but are intermediates in many reactions involving oxidations by chromate.
text: Zinc(I) compounds are rare and need bulky ligands to stabilize the low oxidation state.
text: Compounds that feature scandium in oxidation states other than +3 are rare but well characterized.
text: Compounds of ytterbium are rare and have not yet been well characterized.