Tetraphosphinitoresorcinarene Complexes: Cationic Silver(I) and Copper(I) Halide Complexes as Mercurate(II) Anion Receptors

The reactions of mercury(II) halides with the tetraphosphinitoresorcinarene complexes [P4M5X5], where M = Cu or
Ag, X = Cl, Br, or I, and P4 = (PhCH2CH2CHC6H2)4(O2CR)4(OPPh2)4 with R = C6H11, 4-C6H4Me, C4H3S, OCH2CCH, or OCH2Ph, have been studied. The reactions of the complexes with HgX2 when M = Ag and X = Cl or Br
occur with elimination of silver(I) halide and formation of [P4Ag2X(HgX3)], but when M = Ag and X = I, the complexes
[P4Ag4I5(HgI)] are formed. When M = Cu and X = I, the products were the remarkable capsule complexes
[(P4Cu2I)2(Hg2X6)]. When M = Ag and X = I, the reaction with both CuI and HgI2 gave the complexes [P4Cu2I(Hg2I5)]. Many of these complexes are structurally characterized as containing mercurate anions weakly bonded to
cationic tetraphosphinitoresorcinarene complexes of copper(I) or silver(I) in an unusual form of host−guest interaction.
In contrast, the complex [P4Ag4I5(HgI)] is considered to be derived from an anionic silver cluster with an iodomercury(II) cation. Fluxionality of the complexes in solution is interpreted in terms of easy, reversible making and breaking
of secondary bonds between the copper(I) or silver(I) cations and the mercurate anions.