Synthesis and X-ray crystal structure of trimesitylrhodium(III)

Abstract

The first neutral homoleptic aryl of rhodium(III), Rh(2,4,6-Me₃C₆H₂)₃, has been made by interaction of RhCl₃(C₄H₈S)₃ and mesitylmagnesium bromide; the X-ray crystal structure suggests that there is ‘agostic’ interaction between Rh and an ortho-CH₃ group in a distorted fac-octahedral geometry, but solution spectroscopic data show no evidence for agostic hydrogen bonding; ¹H NMR spectra over a temperature range indicate synchronized rotation of the mesityl group about the Rh–C bond for which ΔG^‡ is ca. 63 kJ mol^–1.