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Coordination Chemistry of SCS Pd II Pincer Systems
Author(s) -
Manen HenkJan van,
Nakashima Kazuaki,
Shinkai Seiji,
Kooijman Huub,
Spek Anthony L.,
Veggel Frank C. J. M. van,
Reinhoudt David N.
Publication year - 2000
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 - 10.1002/1099-0682(200012)2000:12<2533::aid-ejic2533>3.0.co;2-e
Subject(s) - chemistry , pincer movement , steric effects , thiourea , acetonitrile , substituent , ligand (biochemistry) , coordination complex , palladium , aryl , pincer ligand , medicinal chemistry , coordination sphere , crystal structure , stereochemistry , crystallography , organic chemistry , catalysis , metal , biochemistry , alkyl , receptor
We have studied the coordination of substituted pyridines, and phosphorus‐ and sulfur‐containing ligands to an SCS Pd II pincer system. These ligands coordinate to Pd II ( trans to the cyclopalladated aryl group) by quantitative substitution of the labile acetonitrile ligand in complex 1 . Competition experiments showed that both electronic and steric effects influence the strength of coordination to the Pd II pincer of the substituted pyridines. A quantitative analysis of the substituent effect was achieved by a Hammett correlation. Phosphorus‐containing ligands also coordinate to this SCS Pd II motif, as evidenced by NMR spectroscopy and single‐crystal X‐ray diffraction studies. They are much stronger ligands than the pyridines. The coordination strength of the thioureas falls in between those of the pyridines and phosphanes/phosphites. Our results lead therefore to the following order of ligand strength towards Pd II in SCS Pd II pincers: PR 3 > P(OR) 3 > N , N′ ‐disubstituted thiourea > (substituted) pyridines > MeCN.