om049203c_si_002.cif (213.88 kB)

Synthesis and Structural Characterization of Magnesium Amide Complexes Containing −N[(R)(SiMe3)] Ligands

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posted on 28.02.2005, 00:00 by Yongjun Tang, Lev N. Zakharov, Arnold L. Rheingold, Richard A. Kemp
Reaction of anhydrous magnesium bromide with 2 equiv of Me3Si(R)NLi (R = i-Pr, benzyl, mesityl, and SiMe2t-Bu) in diethyl ether at ambient temperature followed by treatment with donor solvents such as THF, hexamethylphosphoramide (HMPA), pyridine (py), or 4-(dimethylamino)pyridine (DMAP) affords [(Me3Si)(R)N]2Mg(L)n [R = i-Pr, L = DMAP, n = 2, 1; R = benzyl, L = DMAP, n = 2, 2; R = benzyl, L = HMPA, n = 2, 3; R = mesityl, L = THF, n = 2, 4; R = mesityl, L = py, n = 2, 5; R = SiMe2t-Bu, L = py, n = 1, 9]. If R is cyclohexyl (Cy), the reaction in diethyl ether initially yields the solvent-free dimer Mg2[N(Cy)(SiMe3)]4, 6, which reacts with excess DMAP to yield Mg[N(Cy)(SiMe3)]2(DMAP)2, 7. If R is either the sterically crowded ligand SiPh2t-Bu or adamantyl (Ad), the reaction produces solvent-free Mg[N(SiPh2t-Bu)(SiMe3)]2, 8, and Mg[N(Ad)(SiMe3)]2(Et2O), 10, respectively. All of these complexes were characterized by spectral and analytical data. The structures of complexes 1, 2, and 410 were confirmed by single-crystal X-ray diffraction analyses.

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