Comparison of halogen bonding networks with Ru(ii) complexes and analysis of the influence of the XB interactions on their reactivity

Coordination compounds of formula [Ru(Cl)₂(CNR)₄] are interesting building blocks for the preparation of halogen bonding supramolecular networks, since the chloride ligand is a good XB acceptor. When using I₂ as the XB donor, an unexpected reaction on the ruthenium coordination sphere happens where the chloride ligands are substituted by iodides. The isolation of several intermediates with different substitution degrees and showing XB interactions in a solid state network evidenced the clear influence of the XB species in this unusual reaction process. The extension of the studies to bromine gave the analogous result, i.e. the substitution of the chloride ligands by bromides. Furthermore, changing the organic substituent in the isocyanide ligands from alkyl to aryl does not affect the outcome of the reaction; however the process is faster when the alkyl substituents are present. In the course of the study of these reactions we have isolated a whole range of XB-based networks were interactions such as Cl⋯I–I, Br⋯Br–Br, I⋯I–I and I⋯Br–Br are present, a systematic comparison of the XB structural features for the different networks isolated and the influence in their reactivity has been performed.