Stability constants of aza-oxa-crown ether complexes with silver(I) in nonaqueous polar solvents

Enhanced Silver Ion Binding to a Rigid Bisarene Molecular Cleft with Formation of Nonpolar Pleated Sheets through Non-Ionic Intermolecular Forces

Silver ion complexation to bisarene ligands is enhanced by providing a conformationally rigid molecular cleft in the (Z)-acenaphthylene dimer 1. NMR titrations were used to determine complexation constants K for a series of ligands in tetrahydrofuran solution, with K = 4.9 M(-1) for the Z dimer 1 and 0.4 M(-1) for the E dimer 2. Higher values of K were observed in CDCl(3)/CD(3)OD 9:1 with K = 38 M(-1) for 1 and K = 4.1 M(-1) for 2. In the solid state, isolated clusters of [1 x (AgCF(3)SO(3))(2)](2) form a novel, pleated-sheet motif based on non-ionic interactions between clusters.

Solvation Effects on the Stability of Silver(I) Complexes with Pyridine-Containing Ligands Studied by Thermodynamic and DFT Methods

The formation of Ag(I) complexes with 2,2'-bipyridine (bipy), 2,2'6',2' '-terpyridine (terpy), 2-(aminomethyl)pyridine (amp), and bis((2-pyridyl)methyl)amine (dpa) is studied in dimethyl sulfoxide (dmso) by means of potentiometric and calorimetric measurements. Enthalpy-stabilized mononuclear MLj complexes are formed, whereas entropy changes counteract complex formation. Additionally, a comparison with analog Ag-polyamine species is made to evidence the significant different coordination behavior of these classes of ligands. The results are discussed in terms of different basicity and steric requirements of the ligands and solvation effects. The dpa ligand, with an unprecedented coordination pattern, forms also a bimetallic complex [Ag2(dpa)2]2+ that has been structurally characterized in the solid state by X-ray diffraction. The influence of solvent, water and dmso, on the binding energy of the monodentate pyridine to Ag(I) has also been assessed by means of density functional theory (DFT) calculations. This study has been extended also in vacuum to the reaction of Ag(I) with the simple monoamine methylamine (mea). These results are correlated with the experimental evidence and used to interpret the different affinities of pyridine for the Ag(I) ion in the two media.