New insights into silver(II) chemistry: synthesis and properties of trifluoroacetate complexes

A silver complex in the +2 oxidation state, K₃Ag(CF₃COO)₅(CF₃COOH)(H₂O)₂ (I), and mixed +1/+2 oxidation-state silver complexes, K₂Ag^IIAgI2(CF₃COO)₆(CF₃COOH)(H₂O) (II), Cs₂Ag^IIAgI2(CF₃COO)₆ (III), K₃Ag^IIAgI3(CF₃COO)₈(H₂O) (IV), K₃Ag^IIAgI3(CF₃COO)₈ (V), and Cs₃Ag^IIAgI3(CF₃COO)₈ (VI) were synthesized by varying the reaction conditions between Ag^IAg^IIIO₂ and trifluoroacetic acid (CF₃COOH, TFAH). Their crystal structures were determined by single-crystal X-ray diffraction analysis. The coordination environment of Ag(II) in structures I-VI is close to square planar, and stabilization of Ag(II) in these complexes is achieved through the incorporation of large monovalent cations-potassium or cesium. The paramagnetic behavior of compounds I-IV and VI was confirmed by magnetic measurements, including temperature-dependent magnetic susceptibility measurements in the range of 2-300 K and field-dependent magnetization measurements. The ESR properties of compounds I-VI were investigated at room temperature, with g-values in the range of 2.121-2.146. The thermal decomposition of compounds I-VI involves redox processes near 100 °C, leading to the formation of silver(I) complexes at an intermediate stage; complete decomposition occurs at 225-250 °C, yielding metallic silver and potassium fluoride (compounds I, II, IV, V) or cesium fluoride (compounds III, VI), respectively. The crystal structures of the silver(I) complexes MAg₂(CF₃COO)₃(CF₃COOH)₄ (M = K (VII), M = Cs(VIII)) and Cs₂Ag₂(CF₃COO)₄(CF₃COOH) (IX) were also determined by single-crystal X-ray diffraction analysis.