Neutral and Cationic Fluorinated N-Heterocyclic Carbene Complexes of Rhodium and Iridium

Transmetalation of the structurally characterized silver N-heterocyclic carbene (NHC) salt [Ag(IpFMe) 2 ] + ( 1, IpFMe = 1-pentafluorobenzyl-3-methylimidazol-2-ylidene) to [Rh(COD)Cl] 2 affords Rh(IpFMe)(COD)Cl ( 2 ). The analogous neutral iridium complex, Ir(IpFMe)(COD)Br ( 5 ), may be formed upon elimination of MeOH from [Ir(COD)(OMe)] 2 in the reaction with 1-pentafluorobenzyl-3-methylimidazolium bromide. Thermolysis of [Ag(IpFMe) 2 ] + with either 5 or [Ir(COD)Cl] 2 yields the cationic bis-NHC complex [Ir(IpFMe) 2 (COD)](AgX 2 ) ( 6, X = Cl, Br), which exists as a mixture of conformers in solution. Addition of CO or AgOTf to 2 gives Rh(IpFMe)(CO) 2 Cl ( 3 ) and Rh(IpFMe)(COD)(OTf) ( 4 ), respectively. The molecular structures of compounds 1 − 6 have been determined by X-ray crystallography.