Coordination chemistry of mercury-containing anticrowns. Synthesis and structure of an unusual discrete, double-decker sandwich complex of cyclic trimeric perfluoro-o-phenylenemercury with an aromatic hydrocarbon

The reaction of the three-mercury anticrown (o-C6F4Hg)3 (1) with [2.2]paracyclophane (PCP) yields a complex {[(o-C6F4Hg)3]2(PCP)} (2), having a double-decker sandwich structure in the crystal. The PCP ligand in 2 is located between the mutually parallel planes of the two anticrown units and it coordinates to them by its benzene rings in an η2:η2:η2 fashion. As a result of such a type of the bonding, all carbon atoms of the benzene rings of PCP are involved in the coordination to the Lewis acidic Hg sites of the anticrown species. The synthesized 2 is the first example of a discrete, double-decker sandwich complex of macrocycle 1 with an aromatic hydrocarbon as well as the first complex of PCP in which both benzene rings of the PCP molecule are η2:η2:η2 bonded to trimetal units.