Structural adaptability and hydrogen bonding in a dissymmetric pyrimidine thioether ligand

Dissymmetric ligands have garnered interest due to their ability to simultaneously coordinate to multiple different acceptors. Herein, we report the synthesis of a dissymmetric thioether N , N ′-bidentate ligand, namely, 2-[(6-chloropyrimidin-4-yl)sulfanyl]pyrimidine-4,6-diamine (C 8 H 7 ClN 6 S, L1 ), along with its hydrated form (C 8 H 7 ClN 6 S·H 2 O). In addition, we describe the structure of a nitrate salt of the protonated ligand {4,6-diamino-2-[(6-chloropyrimidin-4-yl)sulfanyl]pyrimidin-1-ium nitrate, C 8 H 8 ClN 6 S + ·NO 3 − } and a cobalt(II) complex of L1 (dichlorido{2-[(6-chloropyrimidin-4-yl-κ N 3 )sulfanyl]pyrimidine-4,6-diamine-κ N 3 }cobalt(II), [CoCl 2 (C 8 H 7 ClN 6 S)]). The structures of all four compounds were determined by single-crystal X-ray diffraction and Hirshfeld surface analyses were performed. These analyses reveal unengaged hydrogen-bond donors and acceptors in both the neutral ligand and its water solvate, while protonation or metal coordination induces a conformational change that enables full engagement of hydrogen-bond donors. These structural insights have implications for the molecular design of ligands in ion-sensing applications.