A multi state-CASPT2 vs. TD-DFT study of the electronic excited states of RCo(CO)(4) (R = H, CH3) organometallic complexes

Ambrosek D; Villaume S; Gonzalez L; Daniel C

Chemical Physics Letters, Vol.417, No.4-6, 545-549, 2006

DOI10.1016/j.cplett.2005.10.056 Export Citation

A multi state-CASPT2 vs. TD-DFT study of the electronic excited states of RCo(CO)(4) (R = H, CH3) organometallic complexes

Ambrosek D, Villaume S, Gonzalez L, Daniel C

The electronic spectroscopy of RCo(CO)(4) (R = H, CH3) has been investigated by means of MS-CASPT2/CASSCF and TD-DFT calculations. The UV energy domain of the absorption spectrum is dominated by a series of low-lying E-1 metal-to-sigma-bond-charge-transfer (MSBCT) and E-1 and (1)A(1) metal-to-ligand-charge-transfer (MLCT) allowed transitions corresponding to 3d(Co) -> sigma*(Co-R) and 3d(Co) -> pi*(CO) excitations, respectively, slightly red shifted (by ca. 1800 cm(-1)) in the methyl substituted complex. TD-DFT underestimates the transition energies calculated by MS-CASPT2 by more than 0.5 eV and predicts some of the MLCT states to be intercalated between the two low-lying MSBCT states. (c) 2005 Elsevier B.V. All rights reserved.