Reactions of Group 4 Metallocene Complexes with Mono‐ and Diphenylacetonitrile: Formation of Unusual Four‐ and Six‐Membered Metallacycles |
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Authors: | Lisanne Becker Dr Vladimir V Burlakov Dr Perdita Arndt Dr Anke Spannenberg Dr Wolfgang Baumann Dr Haijun Jiao Prof?Dr Uwe Rosenthal |
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Institution: | 1. Leibniz‐Institut für Katalyse e.V. an der Universit?t Rostock, Albert‐Einstein‐Stra?e 29a, 18059 Rostock (Germany), Fax: (+49)?381‐1281‐51176;2. A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov St. 28, 119991, Moscow (Russia) |
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Abstract: | Reactions of Group 4 metallocene alkyne complexes Cp′2M(η2‐Me3SiC2SiMe3)] ( 1 : M=Zr, Cp′=Cp*=η5‐pentamethylcyclopentadienyl; 2 a : M=Ti, Cp′=Cp*, and 2 b : M=Ti, Cp′2=rac‐(ebthi)=rac‐1,2‐ethylene‐1,1′‐bis(η5‐tetrahydroindenyl)) with diphenylacetonitrile (Ph2CHCN) and of the seven‐membered zirconacyclocumulene 3 with phenylacetonitrile (PhCH2CN) were investigated. Different compounds were obtained depending on the metal, the cyclopentadienyl ligand and the reaction temperature. In the first step, Ph2CHCN coordinated to 1 to form Cp*2Zr(η2‐Me3SiC2SiMe3)(NCCHPh2)] ( 4 ). Higher temperatures led to elimination of the alkyne, coordination of a second Ph2CHCN and transformation of the nitriles to a keteniminate and an imine ligand in Cp*2Zr(NC2Ph2)(NCHCHPh2)] ( 5 ). The conversion of 4 to 5 was monitored by using 1H NMR spectroscopy. The analogue titanocene complex 2 a eliminated the alkyne first, which led directly to Cp*2Ti(NC2Ph2)2] ( 6 ) with two keteniminate ligands. In contrast, the reaction of 2 b with diphenylacetonitrile involved a formal coupling of the nitriles to obtain the unusual four‐membered titanacycle 7 . An unexpected six‐membered fused zirconaheterocycle ( 8 ) resulted from the reaction of 3 with PhCH2CN. The molecular structures of complexes 4 , 5 , 6 , 7 and 8 were determined by X‐ray crystallography. |
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Keywords: | metallacycles N ligands titanium zirconium |
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