5,5'-Diamino-2,2'-bipyridine: a versatile building block for the synthesis of bipyridine/catechol ligands that form homo- and heteronuclear helicates.
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-).
Albrecht
Markus
M
Institut für Organische Chemie der RWTH-Aachen, Landoltweg 1, 52074 Aachen, Germany. markus.albrecht@oc.rwth-aachen.de
Janser
Ingo
I
Lützen
Arne
A
Hapke
Marko
M
Fröhlich
Roland
R
Weis
Patrick
P