The Effect of the “Inert” Counteranions in the Deprotonation of the Dihydrogen Complex trans-[FeH(η2-H2)(dppe)2]+: Kinetic and Theoretical Studies
journal contributionposted on 03.03.2004, 00:00 by Manuel G. Basallote, Maria Besora, Joaquín Durán, M. Jesús Fernández-Trujillo, Agustí Lledós, M. Angeles Máñez, Feliu Maseras
Kinetic studies indicate that trans-[FeH(H2)(dppe)2]+ reacts with an excess of NEt3 to form cis-[FeH2(dppe)2] in a single kinetic step. The second-order rate constant is strongly affected by the presence of added salts, an acceleration being observed with BF4- and PF6- salts and a deceleration with BPh4-. Theoretical calculations indicate that the role of the accelerating anions consists of the formation of ion pairs that provide a more effective reaction pathway for deprotonation. However, for the ion pair with the bulky BPh4- anion, steric crowding in the proximities of the dihydrogen ligand hinders the approach of the base, and the reaction is decelerated.