Reaction of Alkylzirconocene Cation Complexes with (R–CC–) 2 SiR 2 Reagents: Preparation of Heterodimetallic Compounds Containing a μ‐Alkynyl Ligand Bridge Between Zirconium and Silicon

The methylzirconocene cation, employed as the [Cp 2 ZrCH 3 (THF)] + BPh 4 − reagent 1a reacts with (R′CC) 2 SiR 2 substrates ( 6a–d ) by means of carbometallation of an alkynyl group to yield the mixed metal ring systems 8a–d , containing both a 1,1‐disubstituted μ‐alkenyl and an alkynyl bridge between zirconium and silicon (e.g. shown by X‐ray crystal structure analyses of complexes 8a and 8c ). A similar addition reaction takes place upon treatment of the (butadiene)zirconocene/tris(pentafluorophenyl)‐borane 1:1 addition product 9 with (CH 3 –CC) 2 Si(CH 3 ) 2 ( 6c ) to give 10 . Here the incipient alkyl zirconocene cation character of the metallocene/borate betaine complex 9 shows up in the alkynyl silane carbometallation reaction.