کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1328602 | 977599 | 2006 | 9 صفحه PDF | دانلود رایگان |
A series of heteroleptic calcium η5-C5R5 cyclopentadienides supported by an N-Dipp (Dipp = 2,6-iPr2C6H3)-substituted β-diketiminate ligand have been synthesised by selective protonolysis of the readily available reagent [HC{(C(Me)N(Dipp))}2Ca{N(SiMe3)2}(THF)] with tetramethylcyclopentadiene, fluorene, indene or cyclopentadiene. No reaction was observed with pentamethylcyclopentadiene, presumably for steric reasons. The tetramethylcyclopentadienyl, fluorenyl and indenyl compounds were characterised by variable temperature 1H NMR and X-ray crystallography. Each complex was found to exist as a mononuclear species both in solution and in the solid state and to be highly sterically crowded, as evidenced by the variable temperature NMR studies. DFT (B3LYP/LANL2DZ) calculations on the model complexes [CaH(C5Me4H)], [CaH(C13H9)] and [CaH(C9H7)] indicate that the precise structures of such heteroleptic compounds are a result of both stereoelectronic and steric influences. Attempts to isolate the unsubstituted cyclopentadienyl were unsuccessful, but resulted in the crystallographic analysis of the dimeric calcium siloxide [HC{(C(Me)N(Dipp))}2Ca(μ-OSiMe3)]2.
A series of heteroleptic calcium cyclopentadienides have been synthesised by protonolysis of the β-diketiminto amide [HC{(C(Me)N(Dipp))}2Ca{N(SiMe3)2}(THF)] with the appropriate C–H acids.Figure optionsDownload as PowerPoint slide
Journal: Journal of Organometallic Chemistry - Volume 691, Issue 6, 1 March 2006, Pages 1242–1250