[1](a) Gmelin, Handbuch der Anorganischen Chemie, 8th ed; Verlag Chemie: Weinheim, 1973; Supplement, Vol. 5, part 1. (b) Sheats, J. E. JOM Libr. 1979, 7, 461.
Cobaltocene hexafluorophosphate is readily synthesized from cobalt(II) salts + CpNa, followed by air + HPF6 or NH4PF6. Salts with a wide range of other counterions may be obtained similarly. The cobaltocenium ion[1] may be precipitated from aqueous solution by a variety of large anions. In addition to PF6 -, convenient counterions include Br3 - and I3 -. The simple halides are hygroscopic, but may be obtained in anhydrous form by removal of water under vacuum.
