This contribution includes a series of nucleophilic addition reactions to metal (Co, Rh, Ir) coordinated carbo-cations such as, [(h⁵ -C₅R₅) (h²-vinyl h^3-cyclopentenyl)]⁺salts 5 -7 obtained as the isomerization products of the protonated norbornadiene complexes, [M (h⁵ -C₅R₅) (h⁴-nbd) (M= Co, Rh, Ir)] 1-3. Vinyl cyclopenteny Cationic Complexes react with LiAlH₄ or LiBHEt₃ at one of the terminal allylic positions C₃, to give the corresponding 4-vinylcyclopentene complex selectively. The position of hydride attack was identified by reaction with LiBDEt, to give corresponding deuterated addition product.. Other nucleophiles (MeLi, KCN, NaOMe, KOH) attack at the same position to yield neutral functionalized h²-vinyl h²-cyclopentene complexes, as the addition products in 70-80% yield. All the addition reactions products have been characterized by ¹H NMR,¹³ NMR, Mass spectrometric and elemental analysis. Nucleophilic addition reactions to cationic [(h⁵ -C₅R₅) (h²-vinyl h^3-cyclopentenyl)]⁺ are regio-selective and preferentially attacked the p-allyl unit not the p-vinyl unit of the carbocation fragment, seemingly followed the David, Green, Mingo’s rule, with decrease by one unit of the hapticity of the ligand for example: h³ -allyl to h² -olefin and predominantly endo stereochemistry of the attack with respect to the metal given the reaction is under charge control.

Abul Rahman

School of Science and Mathematics

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