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Photodissociation and Electronic Spectroscopy of [Re(H)(CO) 3 (H‐dab)] (H‐dab=1,4‐diaza‐1,3‐butadiene): Quantum Wavepacket Dynamics Based on Ab Initio Potentials
Author(s) -
BruandCote Isabelle,
Daniel Chantal
Publication year - 2002
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20020315)8:6<1361::aid-chem1361>3.0.co;2-e
Subject(s) - photodissociation , wave packet , ab initio , spectroscopy , chemistry , atomic physics , quantum , 1,3 butadiene , ab initio quantum chemistry methods , photochemistry , physics , molecule , quantum mechanics , catalysis , organic chemistry , biochemistry
The photodissociation dynamics of [Re(H)(CO) 3 (H‐dab)] (H‐dab=1,4‐diaza‐1,3‐butadiene) were studied by means of wavepacket propagations on CASSCF/MR‐CCI potentials calculated for the electronic ground state and low‐lying excited states as a function of two coordinates, q a and q b , that correspond to the Re−H bond homolysis and to the axial CO loss, respectively. The theoretical absorption spectrum is characterized by two bands, one intense peak centered at λ =500 nm (21 000 cm −1 ) and one broad band centered at 310 nm (32 500 cm −1 ). The visible band was assigned to the low‐lying metal‐to‐ligand charge‐transfer (MLCT) states with a main contribution of the a 1 A′→c 1 A′ transition corresponding to the 3d xz →π* dab excitation. The second band calculated in the UV energy domain was assigned to the d 1 A′ (σ Mn−H →π* dab ) state corresponding to a sigma‐bond‐to‐ligand charge‐transfer (SBLCT) state. The photodissociation dynamics of the low‐lying 1 MLCT and 3 SBLCT states following irradiation in the visible energy domain was simulated by wavepacket propagation on the two‐dimensional diabatic potentials V ( q a , q b ) coupled by the spin‐orbit. In contrast to what was found for the manganese analogue, the 1 MLCT state is nonreactive and a rather slow (beyond the ps time scale), nontotal and indirect homolysis of the Re−H bond occurs through 1 MLCT→ 3 SBLCT intersystem crossing.