Multicentered effective group potentials: ligand-field effects in organometallic clusters and dynamical study of chemical reactivity

Abstract

A new multicentered effective group potential (EGP) is obtained for η 6-benzene. Applications on [Ru 4 (H) 4 (C 6 H 6) 4 ] n+ clusters (n=0 or 2) are in excellent agreement with reference DFT studies in terms of geometries, energies and electronic structures. In particular, the small singlet-triplet energy difference (3.8 kcal/mol) in [Ru 4 (H) 4 (C 6 H 6) 4 ] 2+ is very well reproduced. This new EGP is nevertheless not free from the limitations associated to this first generation of molecular pseudopotentials. A cautious analysis of the nature and exact role of this EGP is made, which provides new directions for the elaboration of the next generation of EGPs. In addition, the η 5-cyclopentadienyl EGP has been used to perform a constrained dynamical simulation for the reaction of Cp 2 LaH with H 2. The energy conservation during the simulation as well as the activation barrier extracted from the simulation clearly demonstrate the good behavior of this EGP in the context of molecular dynamics. Anharmonic effects on this reaction are underlined, further demonstrating the high accuracy of the potential energy surface obtained with EGPs. From a more general point of view, such EGPs are expected to provide accurate albeit low-cost ligand-field effects in organometallic clusters or nanoparticles and to allow dynamical studies at the surface of such compounds. Effective Group Potentials; ab initio molecular dynamics; organometallic clusters and nanoparticles; chemical reactivity

Pseudopotentials for hybridized carbon atoms

“…In 2006, Slaviček and Martinez[27] used a multicentered valence electron effective potential based on the ECP methodology to reproduce a methyl group, in the ethane molecule, with the purpose to solve the link atom problem in QM/MM calculations for ground and excited states. In 2010, Raynaud et al[28] used the multicentered EGP methodology to reproduce the ligand‐field in organometallic cluster, for density functional theory (DFT) calculations and dynamic simulations. These molecular pseudopotential methods all rely on the knowledge of the fragment to replace.…”