Erbium acetylacetonate is a coordination compound with the formula Er(C5H7O2)3.

This anhydrous acetylacetonate complex is often discussed but unlikely to exist per se.

The 8-coordinated dihydrate Er(C5H7O2)3(H2O)2 is a more plausible formula based on the behavior of other lanthanide acetylacetonates.

[2] Upon heating under vacuum, the dihydrate converts to the oxo-cluster Er4O(C5H7O2)10.

This behavior, which is also observed for other lanthanide acetylacetonates, further illustrates the implausibility of six-coordinate Er(C5H7O2)3.