title: Trinuclear rhodium complexes and their relevance for asymmetric hydrogenation.
abstract: Various trinuclear rhodium complexes of the type [Rh(3)(PP)(3)(mu(3)-OH)(x)(mu(3)-OMe)(2-x)]BF(4) (where PP = Me-DuPhos, dipamp, dppp, dppe; different ligands and mu-bridging anions) are presented, which are formed upon addition of bases such as NEt(3) to solvate complexes [Rh(PP)(solvent)(2)]BF(4). They were extensively characterized by X-ray diffraction and NMR spectroscopy ((103)Rh, (31)P, (13)C, (1)H). Their in situ formation resulting from basic additives (NEt(3)) or basic prochiral olefins (without addition of another base) can cause deactivation of the asymmetric hydrogenation. This effect can be reversed by means of acidic additives.
authors.affiliation: Leibniz-Institut für Katalyse e. V. Albert-Einstein-Str. 29a, 18059 Rostock, Germany.
authors.forename: Angelika
authors.initials: A
authors.lastname: Preetz
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Baumann
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Drexler
authors.forename: Christian
authors.initials: C
authors.lastname: Fischer
authors.forename: Jiangtao
authors.initials: J
authors.lastname: Sun
authors.forename: Anke
authors.initials: A
authors.lastname: Spannenberg
authors.forename: Oswald
authors.initials: O
authors.lastname: Zimmer
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Hell
authors.forename: Detlef
authors.initials: D
authors.lastname: Heller