Solid-phase condensation of coordinated ?-picoline and pyridine in platinum(IV) complexes

Synthesis and Characterization of Pt(II) Complexes with Pyridyl Ligands: Elongated Octahedral Ion Pairs and Other Factors Influencing1H NMR Spectra

“…Previous limited NMR studies on cis / trans -[Pt II (py) 2 Cl 2 ] and cis / trans -[Pt II (4-Xpy) 2 Cl 2 ] complexes employed pyridine-type ligands having properties in a narrow range. − ,, In CDCl 3 , the H2/6 signal of py in trans -[Pt II (py) 2 Cl 2 ] was shifted downfield by ∼0.3 ppm as compared to free ligand 24 (see footnotes in Table and Supporting Information, Table S5); this characteristic downfield chemical shift change giving a positive value for the parameter Δδ (Δδ = δ complex – δ ligand ) is approximately the expected value and is usually interpreted as resulting from the decrease in the electron density of the ligand upon coordination. ,, …”

“…As an aid in improving methods for the synthesis and characterization of trans -[Pt II (4-Xpy) 2 Cl 2 ] complexes, we explored fundamental features of the NMR spectra of these complexes. The relatively few known cis/trans -[Pt­(py) 2 Y 2 ] and [Pt­(Xpy or X 2 py) 4 ]­Y 2 complexes (mostly with Y = halide or NCS – and X = Me) contain ligands such as py, picolines (Mepy), and lutidines (Me 2 py) of similar donor ability as estimated by the respective p K a values of the protonated ligand, for example, XpyH + , falling within a very limited p K a range. ,,,,− Also, NMR studies often were reported in different solvents . Thus, the dependence of the NMR signals on the properties of the complexes, such as the pyridyl ligand donor ability, was neither well-defined nor understood.…”