Electrophilic methylplatinum complexes: First structure of a hydroxytris(pentafluorophenyl)borate complex

Treatment of [PtMe(2)(bu(2)bpy)] (bu(2)bpy = 4,4'-di-tert-butyl-2,2'-bipyridine) with B(C6F5)(3) in the presence of the ligand L gives, under anhydrous conditions, [PtMeL(bu(2)bpy)][MeB-(C6F5)(3)] {L = CO (1a), C2H4 (2a), PPh(3) (3a)}. Similar reactions performed in the presence of H2O afford [PtMeL(bu(2)bpy)][HOB(C6F5)(3)] {L = CO (1b), C2H4 (2b), PPh(3) (3b)}. In the absence of L, the treatment of [PtMe(2)(bu(2)bpy)] with B(C6F5)(3) and H2O gives [Pt{HOB(C6F5)(3)}Me(bu(2)bpy)] (4), the first published example of a hydroxytris(pentafluorophenyl)borate complex. All of the complexes are fully characterized by NMR and IR spectroscopy and, in the case of complex 4, by an X-ray analysis which confirms the attachment of the [HOB(C6F5)(3)](-) ligand to the square-planar platinum atom via a Pt-O bond of 2.062(2) Angstrom. We propose that, in the presence of water, B(C6F5)(3) forms an adduct [H2OB(C6F5)(3)] (which acts as a strong acid H[HOB(C6F5)(3)]) and this then protonates a PtMe bond of [PtMe(2)(bu(2)bpy)] forming CH4 and [PtMe(bu(2)bpy)](+)[HOB(C6F5)(3)](-). This protonolysis methodology provides an alternative route to the well-established electrophilic methyl-ligand abstraction by B(C6F5)(3) for the production of late transition-metal cations.