Tetraphosphinite Resorcinarene Complexes: Silver(I) Capsule Complexes

Resorcinarene tetraphosphinite ligands, P4, react with silver(I) trifluoroacetate or silver(I) triflate, AgX, to give the
corresponding [Ag4X4(P4)] complexes. The resorcinarene skeleton in these complexes adopts a boat conformation
with the silver(I) phosphinite units on the horizontal, rather than the upright, arene units of the resorcinarene. The
[Ag4X4(P4)] complexes react with free P4 ligand to yield the [Ag2X2(P4)] or [AgX(P4)] complexes, which are characterized
in solution by NMR spectroscopy to have a conformation opposite to that of the [Ag4X4(P4)] complexes; the silver(I)
phosphinite groups are on the upright arene rings of the resorcinarene “boat” instead of the horizontal arene units.
There is an easy equilibrium between these complexes. When X = triflate, the [Ag4X4(P4)] complexes disproportionate
and add aqua ligands during slow crystallization to give “capsule complexes”, which are characterized crystallographically as [Ag10(O3SCF3)10(OH2)6(P4)2], [Ag10(O3SCF3)6(OH2)8(P4)2][ O3SCF3]4, or [Ag13(O3SCF3)13(OH2)7(P4)2]
depending on the resorcinarene tetraphosphinite ligand P4 used. These unusual capsule complexes are formed by
the tail-to-tail self-assembly of pairs of [Ag4(P4)]4+ units linked by additional silver ions that bind to the phenyl
substituents of one resorcinarene through {Ag(η2-C6H5)}+ binding and to the bridging triflate ligands, aqua ligands,
or both of the other resorcinarene unit.