Fluorido difluoroamido complexes F'MNF2 of heavy alkaline earth metals (M = Ca, Sr, Ba) were prepared through the reactions of laser-ablated metal atoms with diluted NF3 and isolated in cryogenic neon and argon matrices. They were characterized using Fourier-transform infrared (FTIR) spectroscopy, 14/15NF3 isotopic substitution and quantum-chemical calculations. The species feature a F'− and a so far unknown side-on coordinated η3-NF2− ligand with the F'−M−N angle decreasing from Ca to Ba. Bonding analyses suggest that the interactions between the metal center and the ligands are mainly of electrostatic nature. Nevertheless, the orbital interaction shows that an electron donation from the ligands into the empty ns and (n – 1)d orbitals of the metal center further contributes to the electronic structure.
