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Syntheses and Characterization of μ,η1,η1-3,5-Di-tert-butylpyrazolato Derivatives of Aluminum

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journal contribution
posted on 07.04.2001, 00:00 by Wenjun Zheng, Holger Hohmeister, Nadia C. Mösch-Zanetti, Herbert W. Roesky, Mathias Noltemeyer, Hans-Georg Schmidt
The 3,5-di-tert-butylpyrazolato (3,5-tBu2pz) derivatives of aluminum [(η1,η1-3,5-tBu2pz)(μ-Al)R1R2]2 (R1 = R2 = Me 1; R1 = R2 = Et, 2; R1 = R2 = Cl, 3; R1 = R2 = I, 4; [(η2-3,5-tBu2pz)3Al], 5; [Al2(η1,η1-3,5-tBu2pz)2(μ-E)(C⋮CPh)2] (E = S (6), Se (7), Te (8)) have been prepared in good yield. Compounds 1 and 2 were obtained by the reactions of H[3,5-tBu2pz] with Me3Al and Et3Al, respectively. Reaction of [(η1,η1-3,5-tBu2pz)(μ-Al)H2]2 with the pyrazole H[3,5-tBu2pz] gave [(η2-3,5-tBu2pz)3Al] (5). The reaction of [(η1,η1-3,5-tBu2pz)(μ-Al)R2]2 (R = H, Me) and I2 yielded 4, while the reaction of 1 equiv of K[3,5-tBu2pz] and AlCl3 afforded 3. In addition, the reaction of [Al2(η1,η1-3,5-tBu2pz)2(μ-E)H2] and HC⋮CPh gave 6, 7, and 8. All compounds have been characterized by elemental analysis, NMR, and mass spectroscopy. The molecular structure analyses of compounds 1, 3, 6, and 7 by X-ray crystallography showed that complexes 1 and 3 are dimeric with two η1,η1-pyrazolato groups in twisted conformation while 6 and 7 with two η1,η1-pyrazolato groups display a boat conformation.