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Ligation of Substituted Pyridines to Metallosalphen Complexes – Crystallographic Characterization of an Unexpected Four‐Component Supramolecular Assembly Comprising a Sterically Demanding Ligand
Author(s) -
EscuderoAdán Eduardo C.,
BenetBuchholz Jordi,
Kleij Arjan W.
Publication year - 2009
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.200900401
Subject(s) - chemistry , steric effects , pyridine , supramolecular chemistry , ligand (biochemistry) , crystallography , ring (chemistry) , stereochemistry , crystal structure , organic chemistry , biochemistry , receptor
The binding properties of various Zn(salphen) complexes with a range of substituted pyridine ligands has been studied in detail using NMR and UV/Vis spectroscopy, X‐ray diffraction analysis and molecular modelling studies. The combined results clearly demonstrate that subtle differences in the ortho ‐substitution pattern on the pyridine ring have a dramatic effect on the strength of the Zn–N pyr interaction. In the case of a double ortho ‐substitution, the pyridine donor is unable to bind to the Zn(salphen) complex as a result of the rigid geometry around the Zn ion and the steric repulsion that results upon ligation. The steric requirements of the pyridine ligand infers a preferred positioning of its pendant groups as to minimize repulsive interactions with the salphen ligand. The crystallization of two separate Zn(salphen) complexes in the presence of 2,6‐dimethylpyridine has furnished two remarkable 4‐component supramolecular structures in which the Zn ion is associated with a water ligand that in turn is surrounded by two pyridine H‐bond acceptors; a result that relates to the inability of this pyridine ligand to directly interact with the Zn metal centre. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)