Roles Played by Carbene Substituents During Ligand Transfer Reactions Between Tungsten Fischer Carbene Complexes and [Pt(COD)Cl2]

Abstract Fischer carbene ligand transfer reactions from [W{C(X)(C6H4‐4‐R}(CO)5] (X = OEt: a series; X = NMe2: b series), containing remote tertiary amino substituents R = Rʹ2N at the phenyl ring, to platinum(II) of [Pt(COD)Cl2] precursors, are studied. The number of carbene ligands transferred per platinum ion in these cases are determined by the electronic and steric properties of the heteroatoms of the carbene ligand. Thus, neutral bis(carbene) complexes, [Pt{C(X)(C6H4‐4‐R)}2Cl2], (R=H (1a); R=NRʹ2 and Rʹ= Me (2a), Ph (3a), or 4-BrC6H4 (4a)), are formed from the ethoxycarbene precursors (X = OEt), while cationic tris(carbene) complexes [Pt{C(X)(C6H4‐4‐R)}3Cl]+ Z−, (R=H (1b) and R=NRʹ2 and Rʹ= Me (2b), Ph (3b), or 4-BrC6H4 (4b)) are obtained from the aminocarbene precursors (X = NMe2), the latter with different counter ions Z– = Cl–, [W(CO)5Cl]– or PF6–. Electro- and spectroelectrochemical studies indicate consecutive oxidations of the individual carbene ligands, but also a lack of electronic interactions across the (X)C=Pt=C(X) linkages.