Reaction of „Jordan′s Cation” [Cp₂ZrCH₃(thf)]⁺ with Amino Acid‐Derived Isocyanates—A First Synthetic Route to Oligopeptide‐Modified Group 4 Bent Metallocene Cation Systems

Abstract

Abstract The organometallic cation [Cp 2 ZrCH 3 (thf)] + , employed as the tetraphenylborate salt ( 1 ), reacts cleanly in 1:1 stoichiometry with the isocyanates 2 derived from valine methyl ester or valylvaline methyl ester, respectively. In each case addition of the Zr–CH3 group to the isocyanate sp‐carbon center is observed with formation of a functionalized zirconocene cation derivative containing a chelating N ‐metallated N ‐acetylvaline methyl ester ( 3a ) or N ‐acetylvalylvaline methyl ester ( 3b ) moiety, respectively, coordinated in the bent metallocene s̀‐ligand plane. The spectroscopic data of 3 , supported by an X‐ray crystal structure analysis of the zirconated dipeptide derivative 3b , have revealed the presence of chelating (η 1 ‐O:η 1 ‐N)‐coordination of the terminal N ‐acetyl groups in addition to a Zr–O=C interaction with the adjacent valyl amido group.