Azido- and thiocyanato-derivatives of some chlorofluorophosphate(V) ions

Abstract

The preparation and characterisation of some solid tetra-ethylammonium chlorofluorophosphates(V), [NEt₄]⁺[PF_nCl_6–n]^–(1 ⩽n⩽ 3), the anions of which were previously known only in mixed systems, are described for the first time. Their reactions with suitable metal pseudohalides (LiN₃ or AgNCS) lead to substitution of the chlorine ligands only. In some instances ligand redistribution involving fluoride occurs. Some of the derivatives have also been prepared by ligand-exchange reactions between appropriate phosphate(V) anions. Several structural assignments have been made on the basis of the observed P–F splitting patterns and the pairwise additivity of ³¹P n.m.r. shifts, although fluxional behaviour was observed in some cases. All the pseudohalogeno-species are unstable, the thiocyanato-compounds isolated as solids decomposing readily at room temperature.