Intramolecular C-H oxidative addition to iridium(I) triggered by trimethyl phosphite in N,N '-diphosphanesilanediamine complexes

摘要

The reaction of [Ir(SiNP)(cod)][PF6] ([1][PF6]) and of IrCl(SiNP)(cod) (5) (SiNP = SiMe2{N(4-C6H4CH3)PPh2}(2)) with trimethyl phosphite affords the iridium(III) derivatives of the formula [IrHClx(SiNP-H){P(OMe)(3)}(2-x)]((1-x)+) (x = 0, 3(+); x = 1, 6) containing the kappa C-3, P, P'-coordinated SiNP-H ligand (SiNP-H = Si(CH2)(CH3){N(4-C6H4CH3)PPh2}(2)). The thermally unstable pentacoordinated cation [Ir(SiNP){P(OMe)(3)}(cod)](+) (2(+)) has been detected as an intermediate of the reaction and has been fully characterised in solution. Also, the mechanism of the C-H oxidative addition has been elucidated by DFT calculations showing that the square planar iridium(I) complexes of the formula [IrClx(SiNP){P(OMe)(3)}(2-x)]((1-x)+) (x = 0, 4(+); x = 1, 7) should be firstly obtained from 2(+) and finally should undergo the C-H oxidative addition to iridium(I) via a concerted intramolecular mechanism. The influence of the counterion of 2(+) on the outcome of the C-H oxidative addition reaction has also been investigated.