Oxorhenium(V) Complexes with 1,3,4‐Triphenyl‐1,2,4‐triazol‐5‐ylidene

Reactions of the oxorhenium(V) complexes [ReOX3(PPh3)2] (X = Cl, Br) with the N‐heterocyclic carbene (NHC) 1,3,4‐triphenyl‐1,2,4‐triazol‐5‐ylidene (LPh) under mild conditions and in the presence of MeOH or water give [ReOX2(Y)(PPh3)(LPh)] complexes (X = Cl, Br; Y = OMe, OH). Attempted reactions of the carbene precursor 5‐methoxy‐1,3,4‐triphenyl‐4,5‐dihydro‐1H‐1,2,4‐triazole (1) with [ReOCl3(PPh3)2] or [NBu4][ReOCl4] in boiling xylene resulted in protonation of the intermediately formed carbene and decomposition products such as [HLPh][ReOCl4(OPPh3)], [HLPh][ReOCl4(OH2)] or [HLPh][ReO4] were isolated. The neutral [ReOX2(Y)(PPh3)(HLPh)] complexes are purple, airstable solids. The bulky NHC ligands coordinate monodentate and in cis‐position to PPh3. The relatively long Re–C bond lengths of approximate 2.1Å indicate metal‐carbon single bonds.