| Summary: | The synthesis and crystal structures of three heteroleptic complexes of Zn(II) and Cd(II) with pyridine ligands (ethyl nicotinate (<b>EtNic</b>), N,N-diethylnicotinamide (<b>DiEtNA</b>), and 2-amino-5-picoline (<b>2Ampic</b>) are presented. The complex <b>[Zn(EtNic)<sub>2</sub>Cl<sub>2</sub>]</b> (<b>1</b>) showed a distorted tetrahedral coordination geometry with two <b>EtNic</b> ligand units and two chloride ions as monodentate ligands. Complexes <b>[Zn(DiEtNA)(H<sub>2</sub>O)<sub>4</sub>(SO<sub>4</sub>)]·H<sub>2</sub>O</b> (<b>2</b>) and <b>[Cd(OAc)<sub>2</sub>(2Ampic)<sub>2</sub>]</b> (<b>3</b>) had hexa-coordinated Zn(II) and Cd(II) centers. In the former, the Zn(II) was coordinated with three different monodentate ligands, which were <b>DiEtNA</b>, H<sub>2</sub>O, and SO<sub>4</sub><sup>2−</sup>. In <b>3</b>, the Cd(II) ion was coordinated with two bidentate acetate ions and two monodentate <b>2Ampic</b> ligand units. The supramolecular structures of the three complexes were elucidated using Hirshfeld analysis. In <b>1</b>, the most important interactions that governed the molecular packing were O···H (15.5–15.6%), Cl···H (13.6–13.8%), Cl···C (6.3%), and C···H (10.3–10.6%) contacts. For complexes <b>2</b> and <b>3</b>, the H···H, O···H, and C···H contacts dominated. Their percentages were 50.2%, 41.2%, and 7.1%, respectively, for <b>2</b> and 57.1%, 19.6%, and 15.2%, respectively, for <b>3</b>. Only in complex <b>3</b>, weak π-π stacking interactions between the stacked pyridines were found. The Zn(II) natural charges were calculated using the DFT method to be 0.8775, 1.0559, and 1.2193 for complexes <b>1</b>–<b>3</b>, respectively. A predominant closed-shell character for the Zn–Cl, Zn–N, Zn–O, Cd–O, and Cd–N bonds was also concluded from an atoms in molecules (AIM) study.
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