 Pa2O5 + SOCl2 ->[400C] PaCl5

3PaCl5 + Al -> 3PaCl4 + AlCl3
PaCl4 + 2K2(COT) -> Pa(COT)2 + 4KCl

Neptunocene and thorocene were made similarly using the tetrachlorides.Plutonocene is the exception here, as there is no stable plutonium(IV) chloride known (Hpy)2PuCl6 had to be used.The later actinides also form complexes with COT but these don't usually assume the classic neutral sandwich structure.