کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1325544 | 1499940 | 2010 | 6 صفحه PDF | دانلود رایگان |
Reaction of [(BDPP)ThCl2(dme)] (1) with 2 equivalents of MeMgBr in OEt2, followed by filtration and layering a toluene solution with hexanes at −30 °C yielded a single large crystal of [{(BDPP)ThX(μ-X)2Mg(OEt2)(μ-Me)}2]·2 toluene (X = Br0.73–0.87/Cl0.13–0.27; 3·2 toluene). This product is the result of halide exchange to form a partially brominated neutral thorium species, which is adducted with MeMgX(OEt2). The complex is then tetrametallic as a result of Mg–Me–Mg bridges. The structure of complex 3 provides direct insight into the process by which halide exchange takes place between electrophilic metal halide complexes and Grignard reagents. This reactivity stands in stark contrast to the reactions of 1 and [(XA2)ThCl2(dme)] (2) with PhCH2MgCl. In these cases the expected dialkyl products, [LTh(CH2Ph)2] [L = BDPP (4) and XA2 (5)], were formed under most conditions. However, addition of a PhCH2MgCl solution to 2 at −78 °C and warming to room temperature after 5 minutes gave [(XA2)Mg(dme)] (6), the product of ancillary ligand transfer from thorium to magnesium, in 30–50% yield.
A diversity of products was obtained in the reactions of alkyl Grignard reagents with NNN- and NON-donor ligated thorium(IV) chloride complexes. With MeMgBr, halide exchange and adduct formation yielded tetrametallic [{LThX(μ-X)2Mg(OEt2)(μ-Mg)}2] (X = Br0.73–0.87/Cl0.13–0.27). By contrast, with PhCH2MgCl, alkylation and/or ligand transfer to magnesium was observed, depending on the conditions.Figure optionsDownload as PowerPoint slide
Journal: Journal of Organometallic Chemistry - Volume 695, Issues 25–26, 1–15 December 2010, Pages 2798–2803