"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 [M(0) (CO)(CNp-F-Ar(DArF2) )(4) ] (M=Mn, Tc, Re; Ar(DArF2) =2,6-(3,5-(CF(3) )(2) C(6) H(3) )(2) C(6) H(2) 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."