Emerging Trends in the Coordination Chemistry of Thiazolidinone-Containing Polydentate Ligands: Unconventional Binding Modes in Silver Complexes.

This work presents an efficient and straightforward method for obtaining two previously described thiazolidinone-based ligands, HAm4DHotaz (-(4-oxothiazolidin-2-ylidene)picolino-hydrazonamide) and Am4Eotaz (-(3-ethyl-4-oxothiazol-idin-2-ylidene)picolinohydrazonamide), with high yield and purity. Moreover, the reactivity of these ligands toward different Ag salts has been explored, resulting in the isolation of four novel coordination complexes: two mononuclear species, Ag(HAm4DHotaz)·HO (·HO) and Ag(Am4Eotaz) (), and two tetranuclear compounds, [Ag(Am4DHotaz)]·8HO (·8HO) and Ag(Am4Eotaz)(NO)(HO)·1.18HO (·1.18HO). The crystal structures of ·HO, , ·1.18HO, and ·3DMF, the latter obtained by recrystallization of [Ag(Am4DHotaz)]·8HO in dimethylformamide, have been determined. Notably, in ·1.18HO, the thiazolidinone moiety shows the unprecedented bridging mode μ-κS:κS. In addition, ·3DMF represents a rare example of a thiazolidinone-containing complex featuring a μ-κN:κS bridge. Moreover, across these complexes, the Am4Rotaz (R = DH or E) ligands display five hitherto unknown coordination modes. These ligands, and the auxiliary donors (present in ·1.18HO), provide different Ag coordination environments: cores with a seesaw geometry in the mononuclear complexes, and , , , , or cores with varied geometries in the tetranuclear ones. Furthermore, structures of the polynuclear species reveal significant argentophilic Ag···Ag interactions, which play a key role in directing the formation of the multinuclear frameworks.