Bis(metallo) Capsules Based on Two Ionic Diphosphines

Self-assembly and characterization of heterodimeric diphosphine capsules formed by multiple ionic interactions are described. The first type of capsules is composed of one novel tetrasulfonato-xantphos ligand and one complementary tetraammonium calix[4] arene. Encapsulation of a transition metal is achieved by self-assembly of a rhodium complex containing the tetraanionic diphosphine ligand and a tetracationic calix[4] arene. The second type of capsules is composed of two oppositely charged diphosphine ligands: one tetrasulfonato-xantphos and one tetraammonium-diphosphine (of the xantphos-, DPEphos-, and 1,2-bis(diphenylphosphino) ethane (dppe)type). Bis(metallo) capsules, that is, simultaneous encapsulation of two different transition metals, are created by self-assembly of a palladium or platinum complex containing a tetracationic ligand and a rhodium complex containing a tetraanionic ligand. Diphosphine ligands with different flexibilities and shapes assemble into metallocapsules with a proper capsular structure, as is indicated by H-1 NMR and 1D-NOESY spectroscopy, ESIMS, and modeling studies.