Density functional theory study of homologous organometallic molecules of the [RhXL2]2 (X = Cl,Br, or I; L = CO,PH3, or PF3) type |
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| Authors: | P SEURET J WEBER T A WESOLOWSKI |
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| Institution: | Department of Physical Chemistry , University of Geneva , 1211 , Geneva 4 , Switzerland |
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| Abstract: | Density functional theory generalized gradient approximation calculations, which were tested in our previous detailed study of RhCl(PF3)2]2 (Seuret et al., 2003, Phys. Chem. chem. Phys., 5, 268–274), were applied for a series of homologous organometallic compounds of the RhXL2]2 (X = Cl, Br, or I; L = CO, PH3, or PF3) type. Various properties of the studied compounds were obtained. Optimized geometries of RhCl(PH3)2]2 and RhCl(CO)2]2 are in very good agreement with available experimental data. Geometries of other compounds as well as other properties (thermochemistry of selected fragmentation channels, barriers to structural changes, frontier orbitals) which are not available experimentally were predicted. All the considered compounds are not planar. Enforcing planarity of the central RhX]2 moiety requires only a small energetic cost ranging from 2.2 to 3.9 kcal mol?1. The analysis of frontier orbitals indicates that the metals provide the most favourable site for the electrophilic attack in all considered compounds. The analysis of the shape of the lowest unoccupied molecular orbitals indicates that the halogens and ligands provide the most favourable site for the nucleophilic attack for RhCl(CO)2]2 or RhCl(PF3)2]. For RhBr(PF3)2]2, RhI(PF3)2]2 and RhCl(PH3)2]2, the nucleophilic attack on the halogen is less probable. Except for RhCl(CO)2]2, the least energetically expensive decomposition channel involves initial separation of ligands. For RhCl(CO)2]2, its decomposition into the RhCl(CO)2 fragments was found to be the least energetically expensive fragmentation reaction which is probably one of the reasons for the known catalytic activity of this compound. |
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