Cation‐Controlled Formation and Interconversion of the fac/fac and mer/mer Stereoisomers of a Triple‐Stranded Helicate |
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Authors: | Xiaofei Chen,Christian Mevissen,Saskia Huda,Christian G b,Iris M. Oppel,Markus Albrecht |
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Affiliation: | Xiaofei Chen,Christian Mevissen,Saskia Huda,Christian Göb,Iris M. Oppel,Markus Albrecht |
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Abstract: | Two biscatecholester ligands with oligoether spacers were used to prepare dinuclear titanium(IV) triscatecholate based helicates. In the case of Li4[( 1 / 2 )3Ti2], “classical” helicates with three internally bound Li+ ions and syn‐oriented ligands in the complex units (fac/fac isomer) were obtained. In the case of the sodium salt Na4[( 2 )3Ti2], a different homochiral dinuclear triple‐stranded helicate with two internally bound Na+ ions was formed. The complex units are anti‐configured, and two of the ligand spacers are connecting internal with external positions of the helicate (mer/mer isomer). Removal of the sodium ions and addition of lithium ions leads to the switching from one topology to the other with an expanded helicate [( 2 )3Ti2]4? as an intermediate. Switching back to the “non‐classical” helicate cannot be observed because severe structural rearrangements would be required. |
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Keywords: | helicate molecular switches self-assembly templates topological isomers |
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