Formation of a sterically crowded iridium(III)-silyl complex from the bulky terphenyl silane H3Si(C6H3Mes2-2,6)

The reaction of [Ir(COE)Cl]2 and Et2PhP in a 1:6 ratio affords the iridium(I) complex (Et2PhP)3(Cl)Ir (4) as orange crystals in good yield (80%). The 1H- and 31P-NMR data are consistent with the structure of 4. The structure of 4 was determined by X-ray crystallography. The sterically hindered iridium(III)-silyl complex 5 is prepared in 63% yield by the reaction of 4 and H3Si(C6H3Mes2-2,6) (Eq. 5). Complex 5 is isolated as colorless crystals that are thermally stable up to the temperature at which they melt (162–163 °C). The 31P- and 29Si-NMR and IR spectroscopic data and the X-ray crystallographic analysis are consistent with the structure of 5.