Self-Assembled Supramolecular Clusters Based on Phosphines and Coinage Metals: Tetrahedra, Helicates, and Mesocates

An array of coordination-driven supramolecular
metal–ligand clusters has been synthesized using polytopic
phosphine ligands and coinage metals (Cu+, Ag+, Au+). Rigid 3-fold or 2-fold symmetric phosphine ligands
have been prepared: 1,3,5-tris­((4-(diphenylphosphino)­ethynyl)­phenyl)­benzene)
(tppepb, L1), 1,4-bis­((diphenylphosphino)­ethynyl)­benzene
(1,4-dppeb, L2), 1,3-bis­((diphenylphosphino)­ethynyl)­benzene
(1,3-dppeb, L3), 2,6-bis­((diphenylphosphino)­ethynyl)­pyridine
(2,6-dppep, L4), and 1,5-bis­((diphenylphosphino)­ethynyl)­naphthalene
(1,5-dppen, L5). Self-assembly
of these ligands with coinage metals produces four different types
of metal–ligand clusters, or in some cases coordination polymers,
depending on number and relative geometry of the phosphine donor atoms.
Supramolecular tetrahedral clusters of the formula M4(L1)4I4 (M =
Cu+, Ag+, Au+) were obtained with
the tppepb ligand, encapsulating solvent molecules (either CH2Cl2 or DMF) as guests within the central cavity
of the clusters. The ligands 1,3-dppeb (L3) and 2,6-dppep (L4) give
achiral, triple-stranded, dinuclear mesocates with the formula M2(L)3I2 (M = Cu+ or Au+). In contrast, the ligand 1,4-dppeb (L2) generates a triple-stranded, dinuclear
helicate with Cu+, but a coordination polymer with Au+ (both with the empirical formula M2(L2)3I2). Finally, coordination
polymers were obtained from 1,5-dppen (L5) with Cu+. The clusters have been fully characterized
by single crystal X-ray crystallography, high-resolution mass spectrometry, 1H NMR, and 31P NMR.