Ligand metalation in an iridiumtris(diisopropylphosphinomethyl)borato complex: Synthesis, molecular structure and reactivity

The reaction of [IrCl(dmso)3] with trisphosphinomethylborato ligand Li(THF){PhB(CH2PiPr2)3} at room temperature results in intramolecular C–H activation of one of the iPr substituents affording two diastereomers of cyclometalated iridium(III) complex [Ir(H)(dmso){PhB(CH2PiPr2)2(CH2PiPrCHMeCH2)}] (1) in high yield in approximately equimolar ratio. NMR spectroscopic characterization indicates that only the diastereomers with the hydride ligand in cis position with respect to the metalacyclic phosphorous atom are formed as confirmed by single crystal X-ray diffraction. Facile ring opening with H2 at room temperature gives dihydride [Ir(H)2(dmso){PhB(CH2PiPr2)3}] (2). However, C–H activation of benzene was not observed.

The reaction of [IrCl(dmso)3] with Li(THF){PhB(CH2PiPr2)3} results in cyclometalation of an iso-propyl substituent to give two diastereomers of iridium(III) complex [Ir(H)(dmso){PhB(CH2PiPr2)2(CH2PiPrCHMeCH2)}] (1) in high yield. While facile ring opening of the four-membered metalacycle is obtained upon reaction with H2, C–H activation of benzene by 1 was not observed.Figure optionsDownload as PowerPoint slide