A structural survey of metal⋯π heteroaromatic supramolecular synthons for metal = tellurium, tin, and gold

Abstract

A survey of tellurium, tin and gold structures containing metal⋯π heteroaromatic interactions has been conducted, and their occurrence correlated with previously described metal⋯π aryl interactions. Metal⋯π heteroaromatic interactions are found for all three metals when the heteroaromatic ring was a pyridine/pyridine-derivative, and these contacts lead usually to 0-D or 1-D aggregates with rare examples of 2-D and 3-D architectures. For each of tellurium and tin, metal⋯π aryl interactions are more likely to form over metal⋯π pyridine interactions, while the reverse is true in the case of gold. These observations are readily correlated with the influence of increasing electron density in the pyridine compared with an aryl ring. In the case of tellurium and tin, for which the metal⋯π interaction involves a metal-based lone pair of electrons being donated to the LUMO of the aryl group, increasing the electron density of the aromatic ring naturally decreases the probability of forming this type of interaction. In the case of gold, where the metal⋯π interaction involves the donation of electron density from the aromatic ring to the gold centre, increasing the electron density of the aromatic ring favours such an interaction. At least for the metals surveyed, metal⋯π interactions are observed in a significant number of their crystal structures, for example up to 6% of all tellurium structures feature Te⋯π aryl interactions as a supramolecular synthon.