Photochemistry of rhodium(I) olefin complexes containing the (hydro)tris(pyrazolyl)borate ligand

Abstract

The photoisomerisation ( λ=400 nm) of [Tp Me2Rh (η 4-1,5-COD)] ( 1), (Tp Me2=hydrotris(3,5-dimethyl)pyrazolyl borate, 1,5-COD=1,5-cyclooctadiene) to [Tp Me2Rh (η 4-1,3-COD)] ( 2) is reported. The photoreaction is an intramolecular (3,4) hydrogen shift of the coordinated 1,5-COD possibly involving an allylrhodium(III) intermediate. The selective photolysis of complex 2 with 336 nm light causes the dissociation of 1,3-COD forming the organometallic fragment {Tp Me2Rh} ( A) as its primary photoproduct. Fragment A is a versatile entry point in the photochemical preparation of new hydrido Rh(III) complexes.