title: Mechanisms and dynamics of protonation and lithiation of ferrocene.
abstract: By elucidating the mechanism of the simplest electrophilic substitution reaction of ferrocene, it was found that the verification of the protonation reaction has been a difficulty. In the work reported here, ab initio chemical dynamics simulations were performed at B3LYP/DZVP level of theory to understand the atomic level mechanisms of protonation and lithiation of ferrocene. Protonation of ferrocene resulted in the agostic and metal-protonated forms. Trajectory calculations revealed that protonation of ferrocene occurs by exo and endo mechanisms, with exo being the major path. H(+) was found to be mobile and hopped from the Cp ring to the metal center and vice versa after the initial attack on ferrocene, with the metal-complex having a shorter lifetime. These results remove the ambiguity surrounding the mechanism, as proposed in earlier experimental and computational studies. Lithiation of ferrocene resulted in the formation of cation-π and metal-lithiated complexes. Similar to protonation, trajectory results revealed that both exo and endo paths were followed, with the exo path being the major one. In addition, lithiated-ferrocene exhibited planetary motion. The major path (exo) followed in the protonation and lithiation of ferrocene is consistent with the observations in earlier experimental studies for other hard electrophiles.
authors.affiliation: School of Chemical Sciences, National Institute of Science Education and Research, Bhubaneswar, Odisha, India. u.lourderaj@niser.ac.in.
authors.forename: Nishant
authors.initials: N
authors.lastname: Sharma
authors.forename: Jayanth K
authors.initials: JK
authors.lastname: Ajay
authors.forename: Krishnan
authors.initials: K
authors.lastname: Venkatasubbaiah
authors.forename: Upakarasamy
authors.initials: U
authors.lastname: Lourderaj