title: Synthesis, structure, and dynamics of six-membered metallacoronands and metallodendrimers of iron and indium.
abstract: In the reaction of the N-substituted diethanolamines (H(2)L(1-3)) (1-3) with calcium hydride followed by addition of iron(III) or indium(III) chloride, the iron wheels [Fe(6)Cl(6)(L(1))(6)] (4) and [Fe(6)Cl(6)(L(2))(6)] (6) or indium wheels [In(6)Cl(6)(L(1))(6)] (5), [In(6)Cl(6)(L(2))(6)] (8) and [In(6)Cl(6)(L(3))(6)] (9) were formed in excellent yields. Exchange of the chloride ions of 6 by thiocyanate ions afforded [Fe(6)(SCN)(6)(L(2))(6)] (7). Whereas the structures of 4, 5 and 7 were determined unequivocally by single-crystal X-ray analyses, complexes 8 and 9 were characterised by NMR spectroscopy. Contrary to what is normally presumed, the scaffolds of six-membered metallic wheels are not generally rigid, but rather undergo nondissociative topomerisation processes. This was shown by variable temperature (VT) (1)H NMR spectroscopy for the indium wheel [In(6)Cl(6)(L(1))(6)] (5) and is highlighted for the enantiotopomerisation of one indium centre [ 1/6[S(6)-5]<==>[1/6[S(6)-5']]. The self-assembly of metallic wheels, starting from diethanolamine dendrons, is an efficient strategy for the convergent synthesis of metallodendrimers.
authors.affiliation: Institut für Organische Chemie, Universität Erlangen-Nürnberg, Henkestrasse 42, 91054 Erlangen, Germany. saalfrank@chemie.uni-erlangen.de
authors.forename: Rolf W
authors.initials: RW
authors.lastname: Saalfrank
authors.forename: Christian
authors.initials: C
authors.lastname: Deutscher
authors.forename: Harald
authors.initials: H
authors.lastname: Maid
authors.forename: Ayuk M
authors.initials: AM
authors.lastname: Ako
authors.forename: Stefan
authors.initials: S
authors.lastname: Sperner
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nakajima
authors.forename: Walter
authors.initials: W
authors.lastname: Bauer
authors.forename: Frank
authors.initials: F
authors.lastname: Hampel
authors.forename: Bernd A
authors.initials: BA
authors.lastname: Hess
authors.forename: Nico J R
authors.initials: NJ
authors.lastname: van Eikema Hommes
authors.forename: Ralph
authors.initials: R
authors.lastname: Puchta
authors.forename: Frank W
authors.initials: FW
authors.lastname: Heinemann