Odd-Numbered\nRing Cluster Tc<sub>9</sub>(μ-O)<sub>9</sub>Cl<sub>6</sub>(OOCCCl<sub>3</sub>)<sub>15</sub>: Synthesis,\nCrystal Structure, and Optical and Thermal Properties

Herein, we report a method for the preparation of the\nfirst odd\nhomometallic and heterovalent nine-centered Tc wheel, [Tc<sub>9</sub>(μ-O)<sub>9</sub>Cl<sub>6</sub>(OOCCl<sub>3</sub>)<sub>15</sub>]. The synthesized compound represents the pioneering instance of\nsuch clusters among d<sub>4</sub> elements and is the fourth instance\nobserved across all metals. The ring was synthesized by a solvothermal\nmethod in a solution of technetium acid in trichloroacetic anhydride.\nBy single-crystal X-ray diffraction (XRD), powder XRD, and FTIR, the\ncrystal structure was established. By UV–vis spectroscopy,\nthermogravimetric analysis, and density functional theory calculations,\nthe optical, thermal, and some chemical properties were studied. The\nmolar extinction coefficients in 16 solvents were determined. The\nheating of the complex in trichloroacetic anhydride leads to the formation\nof carbonyl compounds.