Synthesis of dimetallic μ-alkylideneamido zirconocene dications by a thermodynamically favorable lithium chloride elimination pathway
摘要:
The reagent [butyl-B(C6F5)(3)](-) Li+ reacts with the Complexes CP2ZrCl(N=CHR) (6) (R=CH3 or p-tolyl) at ambient temperature by chloride abstraction. The resulting in situ formed [CP2Zr(N=CHR)](+) cations (8) dimerize under the reaction conditions. After removal of a stoichiometric amount of lithium chloride the corresponding mu-alkylideneamido-bridged dimeric [Cp2Zr(N=CHR)](2)(2+) dications 9a (R=CH3) and 9b (R=p-tolyl) are isolated in yields of ca. 80% (with [butyl-B(C6F5)(3)](-) counteranion). The complexes 9a and 9b are each obtained as mixtures of cis- and trans-isomers. Crystallization from dichloromethane gave pure trans-9a and trans-9b samples, Both were characterized by X-ray crystal structure analyses. Treatment of the dications 9 with acetonitrile gave the respective mononuclear monocationic adduct complexes [Cp2Zr(N=CHR1)NdropC-CH3](+)[butyl-B(C6F5)(3)](-) (16). (C) 2002 Elsevier Science B.V. All rights reserved.
Synthesis of dimetallic μ-alkylideneamido zirconocene dications by a thermodynamically favorable lithium chloride elimination pathway
摘要:
The reagent [butyl-B(C6F5)(3)](-) Li+ reacts with the Complexes CP2ZrCl(N=CHR) (6) (R=CH3 or p-tolyl) at ambient temperature by chloride abstraction. The resulting in situ formed [CP2Zr(N=CHR)](+) cations (8) dimerize under the reaction conditions. After removal of a stoichiometric amount of lithium chloride the corresponding mu-alkylideneamido-bridged dimeric [Cp2Zr(N=CHR)](2)(2+) dications 9a (R=CH3) and 9b (R=p-tolyl) are isolated in yields of ca. 80% (with [butyl-B(C6F5)(3)](-) counteranion). The complexes 9a and 9b are each obtained as mixtures of cis- and trans-isomers. Crystallization from dichloromethane gave pure trans-9a and trans-9b samples, Both were characterized by X-ray crystal structure analyses. Treatment of the dications 9 with acetonitrile gave the respective mononuclear monocationic adduct complexes [Cp2Zr(N=CHR1)NdropC-CH3](+)[butyl-B(C6F5)(3)](-) (16). (C) 2002 Elsevier Science B.V. All rights reserved.