Cyclopentadienylaluminum donor-acceptor complexes - Molecular and supramolecular structure |
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Authors: | Kinga Leszczyńska Janusz Zachara |
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Institution: | Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland |
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Abstract: | Lewis acid-base complexes of cyclopentadienylaluminum derivatives MexCp3−x Al (x = 0-2) and trimethylaluminum with selected aromatic amines (L): dmap = 4-dimethylaminopyridine, py-Me = 4-methylpyridyne, were synthesized and characterized by 1H, 13C, 27Al NMR: Cp3Al · dmap (1), Cp3Al · py-Me (2), MeCp2Al · dmap (3), MeCp2Al · py-Me (4), Me2CpAl · dmap (5), Me2CpAl · py-Me (6), Me3Al · py-Me (7). 1H NMR studies of 3-6 revealed small amounts of the ligand redistribution products. The crystal structures of 1, 2 and 3 were determined by single X-ray diffraction studies. The compounds 1, 2 and 3 are monomeric with Cp ligands bonded to the aluminum center in η1(σ), η1(π) manner. The change of Cp-Al bond character from η1(π) to η1(σ) was found to reasonable correlate with the aromaticity of Cp− ligand described by HOMA index. Analysis of close intra- and intermolecular contacts showed presence of CH?π interactions leading to the formation of 2-D supramolecular networks. It was found that these interactions impact on the coordination sphere of aluminum and the conformation of Cp ring. |
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Keywords: | Cyclopentadienyl Aluminum Amine adducts Supramolecular structure |
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