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.