A Complete Triad of Zero‐Valent 17‐Electron Monoradicals of Group 7 Elements Stabilized by <i>m</i>‐Terphenyl Isocyanides

Abstract

The first consistent series of mononuclear 17-electron complexes of three Group 7 elements has been isolated in crystalline form and studied by X-ray diffraction and spectroscopic methods. The paramagnetic compounds have a composition of [M⁰ (CO)(CNp-F-Ar^DArF2 )₄ ] (M=Mn, Tc, Re; Ar^DArF2 =2,6-(3,5-(CF₃ )₂ C₆ H₃ )₂ C₆ H₂ F) and are stabilized by four sterically encumbering isocyanides, which prevent the metalloradicals from dimerization. They have a square pyramidal structure with the carbonyl ligands as apexes. The frozen-solution EPR spectra of the rhenium and technetium compounds are clearly anisotropic with large ⁹⁹ Tc and ^185,187 Re hyperfine interactions for one component. High-field EPR (Q band and W band) has been applied for the elucidation of the EPR parameters of the manganese(0) complex.