Fig. 4: Synthesis and molecular structures of mononuclear calcium fluorides 4-Dipp and 4-Trip and how they are structurally connected.
From: Enabling nucleophilic reactivity in molecular calcium fluoride complexes
a, Syntheses of [K(DippNON)Ca(THF)F]2 (4-Dipp) and [K(TripNON)Ca(THF)F]2 (4′-Trip) from 1-Dipp or 1-Trip via amide uptake and subsequent metathesis with Me3SnF. b,c, Centrosymmetric molecular structures in the solid state of 4-Dipp (b) and 4′-Trip (c), as determined by X-ray crystallography. The thermal ellipsoids are set at the 30% level. Hydrogen atoms, second disorder component and solvate molecule omitted and selected fragments are shown in the wireframe format for clarity. Selected bond lengths for 4-Dipp are: Ca–F 2.151, K···F 2.560(1) and 2.634(1) Å and for 4′-Trip are: Ca–F 2.143(1), K···F 2.526(2) and 2.532(1) Å. d, Equilibrium between 4-Dipp and 4′-Dipp in benzene solution; the thermodynamic parameters associated with the formation of the ‘stacked’ isomer 4′-Dipp are derived from a Van’t Hoff analysis of integrated 19F NMR signal intensities (in the temperature range of 25–70 °C).
