Tetraphosphinite resorcinarene complexes: Silver(I) capsule complexes

Resorcinarene tetraphosphinite ligands, P-4, react with silver(I) trifluoroacetate or silver(I) triflate, AgX, to give the corresponding [Ag4X4(P-4)] 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(P-4)] complexes react with free P-4 ligand to yield the [Ag2X2(P-4)] or [AgX(P-4)] complexes, which are characterized in solution by NMR spectroscopy to have a conformation opposite to that of the [Ag4X4(P-4)] 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(P-4)] complexes disproportionate and add aqua ligands during slow crystallization to give "capsule complexes", which are characterized crystallographically as [Ag-10(O3SCF3)(10)(OH2)(6)(P-4)(2)], [Ag-10(O3SCF3)(6)(OH2)(8)(P-4)(2)][O3SCF3](4), or [Ag-13(O3SCF3)(13)(OH2)(7)(P-4)(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 [Ag-4(P-4)](4+) units linked by additional silver ions that bind to the phenyl substituents of one resorcinarene through {Ag(eta(2) -C6H5)}(+) binding and to the bridging triflate ligands, aqua ligands, or both of the other resorcinarene unit.