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Cation‐Controlled Formation and Interconversion of the fac / fac and mer / mer Stereoisomers of a Triple‐Stranded Helicate
Author(s) -
Chen Xiaofei,
Mevissen Christian,
Huda Saskia,
Göb Christian,
Oppel Iris M.,
Albrecht Markus
Publication year - 2019
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201904181
Subject(s) - ion , chemistry , ligand (biochemistry) , crystallography , stereochemistry , lithium (medication) , salt (chemistry) , topology (electrical circuits) , receptor , organic chemistry , medicine , biochemistry , mathematics , combinatorics , endocrinology
Abstract Two biscatecholester ligands with oligoether spacers were used to prepare dinuclear titanium(IV) triscatecholate based helicates. In the case of Li 4 [( 1 / 2 ) 3 Ti 2 ], “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 Na 4 [( 2 ) 3 Ti 2 ], 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 ) 3 Ti 2 ] 4− as an intermediate. Switching back to the “non‐classical” helicate cannot be observed because severe structural rearrangements would be required.