Organosilicon-based multifunctional β-diketones and their rhodium and iridium complexes

Six new organosilicon-based bis-, tris-, and tetrakis(beta-diketones) and their Rh(I)(COD) and Ir(I)(COD) (COD = 1,5-cyclooctadiene) complexes have been prepared and characterized. The beta-diketones, (CH(3))(4-n)Si(4-C(6)H(4)CH(COR)(2))(n) (n = 2, 3, 4; R = Me, Et), were prepared from the corresponding aldehydes (CH3)(4-n)Si(4-C(6)H(4)CHO)(n) by reaction with trimethyl phosphite-alpha-diketone adducts. Reaction with [M(COD)(mu-Cl)](2) (M = Rh and Ir) produces the Rh and Ir complexes, three of which have been characterized by X-ray analysis. The beta-diketone moieties are ca. 133 angstrom apart, which leads to intramolecular M...M distances in the complexes averaging ca. 15.6 angstrom. The present organosilicon-based route is expected to be useful for the construction of a variety of polytopic molecules containing either beta-diketone or other functional groups and polygonal or polyhedral metal complexes based on them.