The complex reacts with the highly electrophilic borane HB(C6F5)2 to form a product havi...

The complex reacts with the highly electrophilic borane HB(C₆F₅)₂ to form a product having stoichiometry and the product is a rare example of pentacoordinate carbon.

a. Suggest a structure for this product.

b. An isomer of this product, [(C₅H₅)₂ZrH]⁺ [CH₂ {B(C₆F₅)₂}₂ (μ–H)]^-, has been proposed as a potential Ziegler–Natta catalyst. Suggest a mechanism by which this isomer might serve as such a catalyst.

(See R. E. von H. Spence, D. J. Parks, W. E. Piers, M. MacDonald, M. J. Zaworotko, S. J. Rettig, Angew. Chem., Int. Ed. , 1995 , 34 , 1230.)