Promethocene

Promethocene is a metal-organic compound of promethium with the chemical formula Pm(C5H5)3. It is radioactive and stable in dry air. Promethocene is different from cyclopentadiene complexes of general transition metals and is considered to be ionically bonded. Theoretical calculations show that its Pm natural population analysis (NPA) electronic configuration is 6s0.115d1.194f2.21.

Preparation
Promethocene can be obtained by reacting anhydrous promethium(III) chloride and sodium cyclopentadienide in a tetrahydrofuran medium:


 * 3C5H5Na + PmCl3 → (C5H5)3Pm + 3 NaCl

Chemical properties
Promethocene decomposes when exposed to water to produce promethium(III) hydroxide and cyclopentadiene.