Functional Group Chemistry at the Zirconocene Backbone: Addition Reactions to Pendant Alkynyl Substituents

Abstract

AbstractThe nickel‐catalyzed cross‐coupling of 2‐bromoindene with propynyl‐ or (phenylethynyl)magnesium bromide gives the corresponding 2‐alkynyl‐substituted indenyl ligands. Subsequent deprotonation and transmetallation with the bis(tetrahydrofuran)zirconium tetrachloride adduct yields the corresponding bis(2‐alkynylindenyl)dichloridozirconium complexes 4a and 4b, which cleanly add a Co2(CO)6 unit to their pairs of alkynyl substituents to give the dimetallic complexes 5a and 5b. Complex 5b was characterized by an X‐ray crystal structure analysis. Complex 4a adds HB(C6F5)2 to the alkynyl substituents to yield a mixture of α‐ and β‐(borylalkenyl)metallocenes. Activation of these complexes with MAO gives active ethene polymerization catalysts, and the 4a,4b,6a/MAO systems are also active in propene polymerization.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)