Fluoro Nitrenoid Complexes FN=MF2 (M=Co, Rh, Ir): Electronic Structure Dichotomy and Formation of Nitrido Fluorides N equivalent to MF3

Abstract

The fluoronitrenoid metal complexes FNCoF(2)and FNRhF(2)as well as the first ternary Rh(VI)and Ir(VI)complexes NIrF(3)and NRhF(3)are described. They were obtained by the reaction of excited Group-9 metal atoms with NF(3)and their IR spectra, isolated in solid rare gases (neon and argon), were recorded. Aided by the observed(14/15)N isotope shifts and quantum-chemical predictions, all four stretching fundamentals of the novel complexes were safely assigned. The F-N stretching frequencies of the fluoronitrenoid complexes FNCoF2(1056.8 cm(-1)) and FNRhF2(872.6 cm(-1)) are very different and their N-M bonds vary greatly. In FNCoF2, the FN ligand is singly bonded to Co and bears considerable iminyl/nitrene radical character, while the N-Rh bond in FNRhF(2)is a strong double bond with comparatively strong sigma- and pi-bonds. The anticipated rearrangement of FNCoF(2)to the nitrido Co(VI)complex is predicted to be endothermic and was not observed.