Chasing the Mond Cation: Synthesis and Characterization of the Homoleptic Nickel Tetracarbonyl Cation and its Tricarbonyl‐Nitrosyl Analogue

130 years after Mond discovered the first homoleptic carbonyl complex Ni(CO)4, we report on a [Ni(CO)4].+ salt as the first synthesis of any homoleptic nickel carbonyl cation in the condensed phase. It was prepared by oxidation of nickel metal with the synergistic oxidant Ag[F{Al(ORF)3}2]/0.5 I2 (RF=C(CF3)3) in CO atmosphere. This D2d‐symmetric metalloradical represents the last missing entry among the structurally characterized homoleptic carbonyl cations of Groups 6 to 11. Additionally, the nickel tricarbonyl‐nitrosyl cation [Ni(CO)3(NO)]+ was obtained by usage of NO[F{Al(ORF)3}2] and all products were fully characterized by means of IR, Raman, NMR/EPR, single crystal and powder XRD. The synthesis of the first homoleptic nickel carbonyl cation [Ni(CO)4].+ and the nickel tricarbonyl‐nitrosyl cation [Ni(CO)3(NO)]+ in the condensed phase is reported. They were obtained by oxidation of nickel metal in CO atmosphere and stabilized with a suitable weakly coordinating anion.