It has been found that cyclic pentameric perfluoroisopropylidene-mercury, [(CF3)2CHg]5, is capable of forming complexes with [PPh4]+ Cl- and [PPh4]+ Br- of the type [(CF3)2CHg]5-X2}2-[PPh4]2+ (X = Cl or Br). According to an X-ray diffraction study, the chloride anions in the complex of [(CF3)2CHg]5 with [PPh4]+ Cl- are located above and below the mercury-containing metallacycle, each Cl- anion being coordinated with all the five mercury atoms of [(CF3)2CHg]5.