Stabilisation of [WF ] and WF by Pyridine: Facile Access to [WF (NC H ) ] and WF (NC H ).

The enhanced reactivity of [WF ] over WF has been exploited to access a neutral derivative of elusive WF . The reaction of WF (NC H ) with [(CH ) Si(NC H )][O SCF ] in CH Cl results in quantitative formation of trigonal-dodecahedral [WF (NC H ) ] , which has been characterised as its [O SCF ] salt by Raman spectroscopy in the solid state and variable-temperature NMR spectroscopy in solution. The salt is susceptible to slow decomposition in solution at ambient temperature via dissociation of a pyridyl ligand, and the resultant [WF (NC H ) ] is reduced to WF (NC H ) in the presence of excess C H N, as determined by F NMR spectroscopy. Pentagonal-bipyramidal WF (NC H ) was isolated and characterised by X-ray crystallography and Raman spectroscopy in the solid state, representing the first unambiguously characterised WF adduct, as well as the first heptacoordinate adduct of a transition-metal pentafluoride. DFT-B3LYP methods have been used to investigate the reduction of [WF (NC H ) ] to WF (NC H ) , supporting a two-electron reduction of W to W by nucleophilic attack and diprotonation of a pyridyl ligand in the presence of free C H N, followed by comproportionation to W .