High‐Spin Iron(VI), Low‐Spin Ruthenium(VI), and Magnetically Bistable Osmium(VI) in Molecular Group 8 Nitrido Trifluorides NMF(3)

Pseudo‐tetrahedral nitrido trifluorides N≡MF(3) (M=Fe, Ru, Os) and square pyramidal nitrido tetrafluorides N≡MF(4) (M=Ru, Os) were formed by free‐metal‐atom reactions with NF(3) and subsequently isolated in solid neon at 5 K. Their IR spectra were recorded and analyzed aided by quantum‐chemical calculations. For a d(2) electron configuration of the N≡MF(3) compounds in C (3v) symmetry, Hund's rule predict a high‐spin (3)A(2) ground state with two parallel spin electrons and two degenerate metal d(δ)‐orbitals. The corresponding high‐spin (3)A(2) ground state was, however, only found for N≡FeF(3), the first experimentally verified neutral nitrido Fe(VI) species. The valence‐isoelectronic N≡RuF(3) and N≡OsF(3) adopt different angular distorted singlet structures. For N≡RuF(3), the triplet (3)A(2) state is only 5 kJ mol(−1) higher in energy than the singlet (1)A′ ground state, and the magnetically bistable molecular N≡OsF(3) with two distorted near degenerate (1)A′ and (3)A“ electronic states were experimentally detected at 5 K in solid neon.