78004-77-0Relevant academic research and scientific papers
Five-coordinate platinum-olefin complexes. Synthesis and high-resolution 1H (250, 360 MHz) and 13C (20 MHz) NMR study of the interligand chiral recognition in the formation of diastereomeric [PtCl2(η2-olefin)(6-R′-py-2-CH=NR)]
Van Der Poel, Henk,Van Koten, Gerard
, p. 2950 - 2956 (2008/10/08)
Five-coordinate platinum(II)-olefin complexes of the type [PtCl2(η2-olefin)(6-R′-pyridine-2-carbaldehyde imine)] were obtained from the 1/1 molar reaction of K[PtCl3(η2-olefin)] with 6-R′-pyridine-2-carbaldehyde imine in acetone or methanol. On the basis of the 1H and 13C NMR data (characteristic 1H and 13C chemical shifts and nJ(195Pt-1H), nJ(195Pt-13C) values), a trigonal-bipyrimidal structure is proposed for these complexes in solution. The Cl atoms occupy the axial sites while the 6-R′-pyridine-2-carbaldehyde imine ligand and olefin reside in the equatorial plane. The 1H (60, 100, 250, and 360 MHz) and 13C (20 MHz) NMR spectra of these complexes excluded the occurrence of Pt-N and Pt-olefin bond dissociation/association processes, and temperature-dependent spectra pointed to pure rotation of the olefin around the platinum-olefin bond axis. In the ethylene species, the latter process was detectable owing to the existence of asymmetry in the equatorial plane resulting from the pyridylimine skeleton. Moreover the observation of anisochronous olefinic 13C resonances in the slow-exchange limit revealed unambiguously that in solution the C=C unit in the ground-state structures of five-coordinate platinum-olefin complexes adopts an in-plane equatorial conformation.
