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NMR Observations of Interligand Interference in the Molecular Motion of Double‐Stranded Dinuclear Helicates
Author(s) -
Houjou Hirohiko,
Schneider Nathanaëlle,
Nagawa Yoshinobu,
Kanesato Masatoshi,
Ruppert Romain,
Hiratani Kazuhisa
Publication year - 2004
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200400407
Subject(s) - chemistry , isostructural , stereochemistry , crystallography , ion , proton nmr , nmr spectra database , schiff base , spectral line , crystal structure , organic chemistry , physics , astronomy
Double‐stranded dinuclear complexes with either twisted or parallel arrangements were obtained by reaction between Schiff‐base ligands and Pd II ions. Linear ligands mainly afforded twisted arrangements, while macrocyclic ligands forced the complex to adopt parallel arrangements. In these dinuclear complexes, one isomer could not be converted into the other even upon prolonged heating. The NMR spectra showed that the chemical shifts of the diastereotopic protons can be used as an indicator to distinguish between the arrangements. The NOE cross‐peak characteristics of the complexes with twisted arrangements are interpreted with reference to the crystal structure of a Cu II complex as an isostructural model of the Pd II complex. Variable‐temperature measurements revealed the rotational interference between the ligands of the counterpart strands, the first time that this has been observed for helically arranged complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)