A Joyful Journey: Tungsten(VI) and Tungsten(V) Fluorides Meet <i>N</i> ‐Heterocyclic Carbenes and Cyclic (Alkyl)(Amino)Carbenes

The first complexation of tungsten(VI) fluoride with N-heterocyclic carbenes (NHCs) and a cyclic (alkyl)(amino) carbene (cAAC^Me) is reported, which led to formation of the complexes [(NHC)WF₆] (NHC = IiPr^Me, 1; BIiPr, 2; IMes, 3; IDipp, 4; and SIDipp, 5) and [(cAAC^Me)WF₆] 6. Solid-state structural analysis revealed distorted mono-capped trigonal prismatic geometries for 2 and 3, whereas 6 adopts a pentagonal bipyramidal coordination. Reduction of 1-6 with 0.5 equivalents of TMS-pyr^Me-TMS afforded rare tungsten(V) fluoride complexes [(NHC)WF₅] (NHC = IiPr^Me, 7; BIiPr, 8; IMes, 9; IDipp, 10; and SIDipp, 11). Reduction of 6 with TMS-pyr-TMS yielded the dinuclear, fluoride-bridged complex [(cAAC^Me)WF₅]₂ 12. Subsequent addition of a second equivalent cAAC^Me to 12 gave the mononuclear, seven-coordinated bis-carbene complex [(cAACMe)₂WF₅] 13. Magnetic susceptibility measurements and EPR spectroscopy confirm a predominantly metal-centered d¹ radical in both 12 and 13. These findings expand the scope of tungsten fluoride chemistry by providing rare examples of tungsten(VI) and tungsten(V) complexes stabilized by soft carbon-donor ligands, paving the way for further exploration.