Influence of Metal, Ligand and Solvent on Supramolecular Polymerizations with Transition-Metal Compounds: A Theoretical Study.

The nature of intermolecular interactions governing supramolecular polymerizations is very important for controlling their cooperativity. In order to address this problem, supramolecular columns made of PtII and PdII complexes of oligo(phenylene ethynylene)-based pyridine (OPE) and tetrazolylpyridine ligands (TEP) were investigated through the dispersion-corrected PM6 method. Aromatic, CH-π, M-Cl and metallophilic interactions helped stabilize the supramolecules studied, and their geometries and associated cooperativities were in excellent agreement with experimental data. The OPE ligand and/or the presence of PtII led to stronger metallophilic interactions and also to cooperative supramolecular polymerizations, which clearly suggests that metallophilic interactions are a key factor for controlling cooperativity. The results indicate that sequential monomer addition is in general less spontaneous than the combination of two larger preformed stacks. The present theoretical investigations contribute to the further understanding of the relation between the thermodynamics of supramolecular polymerizations and the nature of different synthons.