Synthesis of Cyclic Boriozirconocenes

Bimetallic Boriozirconocene Complexes with Planar Tetracoordinate Carbon 

The reaction of the trimethylphosphane-stabilized bis (trimethyl) silyl zirconocene 66 (Rj = R2 = SiMe3) with (HBEt2)2 not only gives the anti van t Hoff/Le Bel compound 69, but also the dimeric species Cp[g-(r 1 T 5-C5H4)]ZrC(SiMe3)=C(H)(SiMe3) 2, which 

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