Ionic liquids have been prepared from simple metallocenium cations and bis(trifluoromethanesulfonyl)amide anion (TFSA). Their properties were tunable by the choice of metals and substituents; the ferrocenium salts were deep-blue paramagnetic liquids, which are readily prepared by a one-step solventless reaction, and the cobaltocenium salts were orange diamagnetic liquids.