title: Dicatechol-diimines: easily accessible ligands for the self-assembly of dinuclear triple-stranded helicates.
abstract: Dicatechol ligands 3b-g-H4 are simply prepared by imine formation of 2,3-dihydroxybenzaldehyde 2 with a series of different diamines 1b-g . An X-ray structural analysis was obtained for the butyl-bridged compound 3e-H4, showing an intramolecular proton transfer and the formation of a chinoidic "keto-amine" structure. The dicatechol derivatives 3b-g-H4 form dinuclear triple-stranded helicates M4[(3)3Ti2] with titanium(IV) ions in the presence of alkali-metal carbonate. For the phenyl- and the trans-1,4-cyclohexyl-bridged complexes, K4[(3b)3Ti2] and Na4[(3f)3Ti2], X-ray structures were obtained.
authors.affiliation: Institut fur Organische Chemie der RWTH-Aachen, Professor-Pirlet-Strasse 1, D-52074 Aachen, Germany. markus.albrecht@oc.rwth-aachen.de
authors.forename: Markus
authors.initials: M
authors.lastname: Albrecht
authors.forename: Ingo
authors.initials: I
authors.lastname: Janser
authors.forename: Susanne
authors.initials: S
authors.lastname: Kamptmann
authors.forename: Patrick
authors.initials: P
authors.lastname: Weis
authors.forename: Birgit
authors.initials: B
authors.lastname: Wibbeling
authors.forename: Roland
authors.initials: R
authors.lastname: Frohlich