High‐Spin Iron(VI), Low‐Spin Ruthenium(VI), and Magnetically Bistable Osmium(VI) in Molecular Group 8 Nitrido Trifluorides NMF₃

Abstract

Pseudo‐tetrahedral nitrido trifluorides N≡MF3 (M=Fe, Ru, Os) and square pyramidal nitrido tetrafluorides N≡MF4 (M=Ru, Os) were formed by free‐metal‐atom reactions with NF3 and subsequently isolated in solid neon at 5 K. Their IR spectra were recorded and analyzed aided by quantum‐chemical calculations. For a d2 electron configuration of the N≡MF3 compounds in C3v symmetry, Hund's rule predict a high‐spin 3A2 ground state with two parallel spin electrons and two degenerate metal d(δ)‐orbitals. The corresponding high‐spin 3A2 ground state was, however, only found for N≡FeF3, the first experimentally verified neutral nitrido FeVI species. The valence‐isoelectronic N≡RuF3 and N≡OsF3 adopt different angular distorted singlet structures. For N≡RuF3, the triplet 3A2 state is only 5 kJ mol−1 higher in energy than the singlet 1A′ ground state, and the magnetically bistable molecular N≡OsF3 with two distorted near degenerate 1A′ and 3A“ electronic states were experimentally detected at 5 K in solid neon.

Nitrogen Trifluoride Complexes of Group 10 Transition Metals M(NF3) (M = Pd, Pt)

“…Recently, reactions of group 4, 6, 8, 9, and 11 metals, Th, and U with nitrogen trifluoride in excess neon and argon have been studied, and difluoroamino, fluoronitrenoid and nitride metal complexes (F 2 NMF, FNMF 2 , and NMF 3 ) have been prepared and characterized by matrix-infrared spectroscopy and theoretical calculations. 13–16 In contrast to the nitrogen trifluoride reactions reported above, the analogue ammonia molecule reacted with metal atoms to form M(NH 3 ) complexes first, which rearranged to HMNH 2 via N–H bond insertion upon light excitation. 17 The weak N–F bond, which is only about half as strong as the N–H bond in the NH 3 molecule, 18 makes the insertion reaction easier than that for the N–H bond.…”