Syntheses and characterization of μ,η1,η1-3,5-di-tert-butylpyrazolato derivatives of aluminum

The 3,5-di-tert-butylpyrazolato (3,5-tBu(2)pz) derivatives of aluminum [(eta (1),eta (1)-3,5-tBu(2)pz)(mu -Al)R1R2](2) (R-1 = R-2 = Me 1; R-1 = R-2 = Et, 2; R-t = R-2 Cl, 3; R-1 = R-2 = I, 4; [(eta (2)-3,5-tBu(2)pz)(3)Al], 5; [Al-2(eta (1),eta (1)-3,5-tBu(2)pz)(2)-(mu -E)(C equivalent to 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-tBu(2)pz] with Me3Al and Et3Al, respectively. Reaction of [(eta (1),eta (1)-3,5-tBu(2)pz)(mu -Al)H-2](2) with the pyrazole H[3,5-tBu(2)pz] gave [(eta (2)-3,5-tBu(2)pz)(3)Al] (5). The reaction of [(eta (1),eta (1)-3,5-tBu(2)pz)(mu -Al)H-2](2) (R = H, Me) and It yielded 4, while the reaction of 1 equiv of K[3,5-tBu(2)pz] and AlCl3 afforded 3. In addition, the reaction of [Al-2(eta (1),eta (1)-3,5-tBu(2)pz)(2)(mu -E)H-2] and HC equivalent to 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 eta (1),eta (1)-pyrazolato groups in twisted conformation while 6 and 7 with two eta (1),eta (1)-pyrazolato groups display a boat conformation.