Stabilisation of [WF₅]⁺ and WF₅ by Pyridine: Facile Access to [WF₅(NC₅H₅)₃]⁺ and WF₅(NC₅H₅)₂

Abstract

The enhanced reactivity of [WF 5 ] + over WF 6 has been exploited to access an eutrald erivative of elusive WF 5 . The reactiono fW F 6 (NC 5 H 5 ) 2 with [(CH 3 ) 3 Si(NC 5 H 5 )][O 3 SCF 3 ]i n CH 2 Cl 2 results in quantitative formation of trigonal-dodecahedral [WF 5 (NC 5 H 5 ) 3 ] + ,w hich has been characterised as its [O 3 SCF 3 ] À salt by Ramans pectroscopy in the solid state and variable-temperature NMR spectroscopy in solution.T he salt is susceptible to slow decomposition in solution at ambient temperature via dissociation of ap yridyl ligand, and the resultant [WF 5 (NC 5 H 5 ) 2 ] + is reduced to WF 5 (NC 5 H 5 ) 2 in the presence of excess C 5 H 5 N, as determined by 19 FNMR spectrosco-py.P entagonal-bipyramidal WF 5 (NC 5 H 5 ) 2 was isolateda nd characterised by X-ray crystallography and Raman spectroscopy in the solid state, representing the first unambiguously characterised WF 5 adduct, as well as the first heptacoordinate adduct of at ransition-metal pentafluoride. DFT-B3LYP methodsh ave been used to investigatet he reduction of [WF 5 (NC 5 H 5 ) 2 ] + to WF 5 (NC 5 H 5 ) 2 ,s upporting at wo-electron reductiono fW VI to W IV by nucleophilic attack and diprotonation of ap yridyl ligand in the presence of free C 5 H 5 N, followed by comproportionation to W V .

Stabilisation of [WVF4]+ by N‐ and P‐Donor Ligands: Second‐Order Jahn‐Teller Effects in Octacoordinate d1 Complexes

“…684, 650). The ν s (NC 5 ) bands of the pyridyl ligands in [WF 4 (NC 5 H 5 ) 4 ] + are blue‐shifted (1018 vs. 990 in free C 5 H 5 N) to a similar extent as in WF 5 (NC 5 H 5 ) (1024, 1016) [11] . The ν s (PC 3 ) mode of P(CH 3 ) 3 is comparably shifted in [WF 4 {P(CH 3 ) 3 } 4 ] + (678 vs. 653).…”

“…The cations are found to adopt SA geometries of approximately D 2 symmetry for the WF 4 Pn 4 (Pn=N, P) moieties, in which the donor ligands occupy the opposing vertices of each square face (Figure 1). The W−F bond lengths are significantly longer in [WF 4 (NC 5 H 5 ) 4 ] + (I: 1.918(3)–1.926(3) Å) than in WF 5 (NC 5 H 5 ) 2 , [11] as are the W−N bonds (I: 2.281(4)–2.302(4) vs. 2.2206(15) Å), due to the increased coordination number at the tungsten(V) centre. The W−F bond elongation is more pronounced in the P(CH 3 ) 3 analogue (1.9723(14)–1.9880(14) Å).…”

“…Tungsten hexafluoride (Ozark‐Mahoning) and (CH 3 ) 3 SiO 3 SCF 3 (Alfa Aesar, 99 %) were purified by distillation prior to use. The WF 5 (NC 5 H 5 ) 2 adduct [11] and [(CH 3 ) 3 Si(L)][O 3 SCF 3 ] [46] were prepared as described previously.…”

“…Recently, it was demonstrated that WF 6 , which does not typically behave as a F − donor, relinquishes F − to strong acceptors in the presence of N‐donor ligands to yield donor‐stabilised [WF 5 ] + complexes [10,11] . These complexes are significantly stronger oxidising agents than WF 6 , demonstrated by the reduction of [WF 5 (NC 5 H 5 ) 2 ] + to WF 5 (NC 5 H 5 ) 2 in excess C 5 H 5 N, providing a facile route to a neutral WF 5 complex [11] . Unlike WF 5 , WF 5 (NC 5 H 5 ) 2 is stable towards disproportionation.…”