| Abstract
| - A rhodium(III) complex bearing an ambiphilic ligand, PMe2CH2AlMe2, has been synthesized. This species has an ionizing capability that surpassed the untethered system. Trapping experiments with PMe3 and (PMe2CH2AlMe2)2 (1) allowed the isolation of new zwitterionic species of rhodium(III).
- The addition of the ambiphilic compound (Me2PCH2AlMe2)2 (1) to Cp*RhMe2(DMSO) (DMSO =dimethylsulfoxide) (2) gives Cp*RhMe2(PMe2CH2AlMe2·DMSO) (3·DMSO). The addition of Lewis acids(LA) such as La(dbm)3 (dbm = dibenzoylmethane) and AlMe3 to a solution of complex 3·DMSO givesa competition reaction that results in the formation of LA·DMSO and Cp*RhMe2(PMe2CH2AlMe2) (3).When heated to 40 °C, complex 3 ionizes to a putative zwitterionic species, Cp*Rh+Me(PMe2CH2AlMe3-)(3‘), which is converted to [Cp*Rh(Me)(μ2-η2-Me2PCH2)]2 (4) irreversibly. Spin saturation transferexperiments demonstrated that the rate of the methyl abstraction by the alane moiety was 0.76 ± 0.09s-1, while the rate of abstraction of the methyl in Cp*RhMe2(PMe3) by AlMe3 was 0.10 ± 0.02 s-1. Thezwitterionic species 3‘ could be trapped in solution by addition of PMe3 to afford both Cp*Rh+Me(PMe3)(Me2PCH2AlMe3-) (5) and [Cp*Rh+Me(PMe3)(Me2PCH2AlMe2)]AlMe4- (6). When compound 1 was addedto complex 3‘, the formation of the zwitterionic complex Cp*Rh+Me(η2-Me2PCH2Al-Me2CH2PMe2) (7)was observed.
|
