Does the Central Nitrogen Atom Make a Difference? A Comparison of Non-Coordinating Pyridine and Benzene Spacers in Multitopic Ligands

In metal coordination compounds of the divergent ligands 4,2′:6′,4“-terpyridine and 3,2′:6′,3”-terpyridine and their 4′-functionalized derivatives, the central pyridine ring of the 4,2′:6′,4“-terpyridine and 3,2′:6′,3”-terpyridine domains is non-coordinated. We present an overview of data from the Cambridge Structural Database to assess whether there are structural similarities between the coordination compounds of 4,2′:6′,4“-tpy and 1,3-di(pyridin-4-yl)benzene, and between 3,2′:6′,3”-tpy and 1,3-di(pyridin-3-yl)benzene. Based upon structurally characterized compounds, it emerges that the coordination chemistry of ligands including one or more 4,2′:6′,4“-terpyridine or 3,2′:6′,3”-terpyridine metal-binding domains is more abundantly exemplified than that of corresponding ligands based upon 1,3-di(pyridin-4-yl)benzene and 1,3-di(pyridin-3-yl)benzene. We provide an overview of metallamacrocycles and cages, 1D-coordination polymers and 2D- and 3D-networks.