Is the ground state of [RuO4]2? exceptional?
- 1 January 1995
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 10,p. 1537-1542
- https://doi.org/10.1039/dt9950001537
Abstract
Optimised geometries of [RuO4]n–(n= 0, 1 or 2) have been obtained. While the local density approximation (LDA) of density functional theory (DFT) gives good Ru–O distances for RuO4 and [RuO4]–, the computed bond length for [RuO4]2– is at least 0.07 Å too long. The latter result assumes a conventional 3A1 electronic structure with the two notional d electrons in the essentially antibonding e molecular orbitals. However, a 3E state, derived from the e1a1 1 configuration, is very close in energy and gives a far more satisfactory Ru–O distance although theory does not categorically establish 3E as the outright ground state even after the inclusion of spin-polarisation, lattice, relativistic, Jahn–Teller and non-local functional effects. If the real ground state is 3E then the DFT state energies for [RuO4]2– would appear to be in error by about 10 kcal mol–1. It seems more plausible to accept this error in total energy than the large bond length error associated with the 3A1 state and therefore to conclude that the ground state for tetrahedral [RuO4]2– is 3E.Keywords
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