493029-64-4Relevant academic research and scientific papers
Metal complexes of the tetradentate ligands rac- and meso-N,P,P,N: Synthesis, separation and structural characterization
Mueller, Gabi,Klinga, Martti,Leskelae, Markku,Rieger, Bernhard
, p. 2625 - 2632 (2002)
The N,P,P,N ligand 1,2-bis[(2-quinolinemethyl)(phenyl)phosphanyl]ethane (2) which contains two stereogenic phosphane units in the ligand backbone [rac-2 (R/R, S/S) and meso-2 (R/S)] and two pendant quinaldine moieties was synthesized. The diastereomeric forms were separated after conversion of the ligands to the corresponding palladium(II) diiodide complexes (rac-3, meso-3). The structure of both compounds was determined by X-ray structure analysis and revealed a bidentate coordination through phosphorus leading to the expected square-planar geometry. The free ligands were regenerated by treatment of the palladium(II) diiodides with potassium cyanide and the coordination behavior of rac-2 and meso-2 towards iron(II) and cobalt(II) dichloride (rac-5, meso-5, M = Fe; rac-6, meso-6, M = Co) was investigated by the means of IR and UV/Vis spectroscopy. The results indicate that in the case of FeII and CoII the quinaldine moieties are not coordinated to the metal center and the ligands therefore act, as in the case of PdII, as bidentate systems. UV/Vis investigations suggest a tetrahedral coordination environment for the CoII complexes. The FeII and CoII derivatives were tested for ethene polymerization and the bis(acetonitrile)-palladium compounds (rac-4, meso-4) for ethene/CO copolymerization reactions. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
