Synthesis and crystal structure determination of Mn(II) Schiff base complexes and their performance in ethene polymerization

Autor: Timo Repo, Ahlam Sibaouih, Markku Leskelä, Martin Nieger, Markku Ahlgrén, Enrique Colacio, Minna T. Räisänen, Erkki Aitola, Anjali Sood
Rok vydání: 2013
Předmět:
Zdroj: Polyhedron. 56:221-229
ISSN: 0277-5387
DOI: 10.1016/j.poly.2013.03.063
Popis: Mn(II) complexes 1–10, of which eight are novel, were prepared in high yields by reacting MnCl2 with bidentate N,N′-imine-pyridine and N,N′-imine-quinoline-type donor ligands having different kinds of chemical modifications. The complexes were fully characterized by elemental analysis, mass spectrometry and IR spectroscopy. Crystal structures of 6, 7 and 9 were determined by X-ray crystallography and the results showed that 6 has a dimeric square-pyramidal geometry, whereas 7 and 9 have distorted octahedral structures. Magnetic studies on the high spin complexes 6 and 9 showed that the former exhibits a weak intramolecular antiferromagnetic interaction through the chloride-bridging ligands with a magnetic exchange coupling J = −0.46(6) cm−1, whereas the latter, as expected for its mononuclear structure, only shows very weak intermolecular interactions and/or zero-field splitting effects. All the complexes were activated with methylaluminoxane and investigated under low pressure (5 bar) for ethene polymerization at 60 °C. Complexes 1 and 6–10 showed catalytic activity. The prepared polyethenes exhibited high molar masses (296 000–399 000 g/mol) and high melting temperatures (133–140 °C). The low molar mass distribution values of 2.15–2.55 indicated single-site polymerization behavior.
Databáze: OpenAIRE
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