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

Abstract

Abstract 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)WF 6 ] (NHC = I i Pr Me , 1 ; BI i Pr, 2 ; IMes, 3 ; IDipp, 4 ; and SIDipp, 5 ) and [(cAAC Me )WF 6 ] 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)WF 5 ] (NHC = I i Pr Me , 7 ; BI i Pr, 8 ; IMes, 9 ; IDipp, 10 ; and SIDipp, 11 ). Reduction of 6 with TMS‐pyr‐TMS yielded the dinuclear, fluoride‐bridged complex [(cAAC Me )WF 5 ] 2 12 . Subsequent addition of a second equivalent cAAC Me to 12 gave the mononuclear, seven‐coordinated bis‐carbene complex [(cAACMe) 2 WF 5 ] 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.