Theoretical investigation of the mechanism of the intermolecular proton transfer in carbanion [1.1]ferrocenophane

Abstract

AbstractDensity Functional Theory calculations, with the hybrid functional denoted B3LYP, were used to study of the intramolecular proton transfer in lithium‐reacted [1.1]ferrocenophane (FCP). Geometries of ferrocene (FC) and several FCP complexes, including dimethylated FCP and lithium‐reacted FCP, were fully optimized utilizing the B3LYP and the INDO/1 methods. The B3LYP geometries agree very well with the available experimental geometries. The INDO/1 geometries agree less well but yield reasonable geometries for FC and the FCPs considered in this work. Transition state theory (TST) was used to calculate the intramolecular proton transfer rate in FCP−. Nuclear tunneling along the reaction coordinate was considered by the Wigner correction to the TST rate constant. Nuclear tunneling appears to be very important for the proton transfer. The calculated proton transfer rate at T = 298 K, kpt(298) is 98,690 s−1 and kpt(194) is 2 s−1 compared to the observed rate in tetrahydrofuran solution kobs(298) = 32,000 s−1 and kobs(194) = 63 s−1. A slightly different mechanism than the one previously suggested is proposed based on these calculations. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005