title: 5,5'-Diamino-2,2'-bipyridine: a versatile building block for the synthesis of bipyridine/catechol ligands that form homo- and heteronuclear helicates.
abstract: Herein we present an improved synthesis of 5,5'-diamino-2,2'-bipyridine (1) starting from the pyrrole-protected aminopyridine 4. By standard reactions 1 can easily be transformed into the imine- or amide-bridged dicatechol-bipyridine ligands L1-H4 and L2-H4. Whereas ligand L1 readily forms homodinuclear helicates [(L1)3Ti2]4-, the attempted formation of mono-, tri-, or even oligonuclear coordination compounds from this ligand did not work. However, the amide-connected ligand L2 affords mononuclear ([(L2-H4)PdCl2], [(L2-H4)3Zn]2+), dinuclear ([(L2)3Ti2]4-), and heterotrinuclear coordination compounds ([(L2)3Ti2Zn]2-).
authors: Institut für Organische Chemie der RWTH-Aachen, Landoltweg 1, 52074 Aachen, Germany. markus.albrecht@oc.rwth-aachen.de
authors: Markus
authors: M
authors: Albrecht
authors: Ingo
authors: I
authors: Janser
authors: Arne
authors: A
authors: Lützen
authors: Marko
authors: M
authors: Hapke
authors: Roland
authors: R
authors: Fröhlich
authors: Patrick
authors: P
authors: Weis