Side‐On Coordination in Molecular Alkaline Earth Metal Hypofluorites FM(η ² ‐OF) (M = Mg, Ca, Sr, and Ba)

Abstract

Abstract Side‐on coordinated molecular hypofluorites FM(η 2 ‐OF) (M = Mg, Ca, Sr, and Ba) were prepared by co‐deposition of laser‐ablated alkaline earth metal atoms with diluted OF 2 in cryogenic matrices. The structures parallel the non‐VESPR structures of alkaline earth metal difluorides and dihydrides, such that FMg(η 2 ‐OF) is planar, FCa(η 2 ‐OF) is planar but with a shallow bending‐potential curve, while FSr(η 2 ‐OF) and FBa(η 2 ‐OF) are non‐planar. Bonding analyses show that the interactions between the metal center M 2+ and the negatively charged ligands F − and OF − are mainly electrostatic. Moreover, for FMg(η 2 ‐OF), donation of electron density from OF − to empty s and p orbitals of magnesium is involved. However, for the heavier alkaline earth metal compounds, the donation to empty d orbitals of the metal center becomes dominant in orbital interactions, which contributes to their non‐planar structures.