title: Exploring the palladium- and platinum-bis(pyridine) complex motif by NMR spectroscopy, X-ray crystallography, (tandem) mass spectrometry, and isothermal titration calorimetry: do substituent effects follow chemical intuition?
abstract: A series of ten palladium-bis(pyridine) complexes, as well as their corresponding platinum complexes, have been synthesized. The pyridine ligands in each series carried different σ-donor and/or π-acceptor/donor substituents at the para-position of their pyridine rings. These complexes were analysed by NMR spectroscopy, X-ray crystallography, (tandem) MS, and isothermal titration calorimetry (ITC) to validate whether these methods allowed us to obtain a concise and systematic picture of the relative and absolute thermodynamic stabilities of the complexes, as determined by the electronic effects of the substituents. Interestingly, the NMR spectroscopic data hardly correlated with the expected substituent effects but the heteronuclear platinum-phosphorus coupling constants did. Crystallographic data were found to be blurred by packing effects. Instead, tandem MS and ITC data were in line with each other and followed the expected trends.
authors.affiliation: Kekulé-Institut für Organische Chemie und Biochemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany.
authors.forename: Torsten
authors.initials: T
authors.lastname: Weilandt
authors.forename: Nora L
authors.initials: NL
authors.lastname: Löw
authors.forename: Gregor
authors.initials: G
authors.lastname: Schnakenburg
authors.forename: Jörg
authors.initials: J
authors.lastname: Daniels
authors.forename: Martin
authors.initials: M
authors.lastname: Nieger
authors.forename: Christoph A
authors.initials: CA
authors.lastname: Schalley
authors.forename: Arne
authors.initials: A
authors.lastname: Lützen