Dihydrogen mediated hydrogen transfer reactions

Document Type

Conference Proceeding

Publication Date

1-1-2009

Abstract

While developing a comprehensive potential energy surface for N2H4 at CBS-QB3 and CCSD(T)/6-311+G(2df,2p) levels of theory to uncover chemical activation reactions of amidogen radicals (NH2), we have revealed a new stereoselective reaction pathway which can be considered as the simplest model for the symmetric-synchronous double hydrogen-atom abstraction reaction from an H-donor as cis-diazene molecule: cis-N2H2 +H2 虠 N2+H2+H2. We show that this ring-transition state mechanism is functioning in both gas- and condensed phases, in different environments, with a variety of neutral and ionic structures. In metallorganic models the hydridic H-atoms are pre-activated reducing the activation barriers. The barrier height for the catalytic reaction with simple (CH3)2FeH2 cluster, for instance, is fairly low (6.0 kcal mol-1) compared to the 22.5 kcal mol-1 barrier in the gas-phase. Based on these observations, we have also discovered a new type of remote H-transfer reactions between virtually any of the two remote active centers of a Fe2-organic cluster involving CO, CN and SH ligands, which represent ligands in the models of Hydrogenase enzyme. The reactant H2 molecule in this case is a transferor of H atoms from, e.g., a bridged S to the distal Fe atom. Calculations were performed at the B3LYP all electron 6-311+(G(2d,2p) DFT level as well as using Los Alamos effective core potential for Fe and Dunning-Hay double zeta basis set for the remaining atoms for more complex systems as implemented in Gaussian-03 suite of programs.

Identifier

84946543786 (Scopus)

ISBN

[9781615676682]

Publication Title

Fall Meeting of the Eastern States Section of the Combustion Institute 2009

First Page

257

Last Page

262

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