Intramolecular Spodium Bonds in Zn(II) Complexes: Insights from Theory and Experiment

Two new dinuclear zinc(II) complexes, [Zn₂(µ_1,3-OAc)(L¹)₂]I·MeOH (1) and [Zn₂(µ_1,3-OAc)(L²)(NCS)] (2), (where HL¹ = 2-(((3-(dimethylamino)propyl)amino)methyl)-6-methoxy-phenol and H₂L² = 2,2′-[(1-Methyl-1,2-ethanediyl)bis(iminomethylene)]bis[6-ethoxyphenol]) have been synthesized and characterized by elemental and spectral analysis. Their X-ray solid state structures have been determined, revealing the existence of intramolecular Zn···O spodium bonds in both complexes due to the presence of methoxy (1) or ethoxy (2) substituents adjacent to the coordinated phenolic O-atom. These noncovalent interactions have been studied using density functional theory (DFT) calculations, the quantum theory of “atoms-in-molecules” and the noncovalent interaction plot. Moreover, a search in the Cambridge structure database (CSD) has been conducted in order to investigate the prevalence of intramolecular spodium bonds in Zn complexes. To our knowledge this is the first investigation dealing with intramolecular spodium bonds.