The Character of Low-Lying Excited States of Mixed-Ligand Metal Carbonyls. TD-DFT and CASSCF/CASPT2 Study of [W(CO)4L] (L = ethylenediamine, N,N'-dialkyl-1,4-diazabutadiene) and [W(CO)5L] (L = pyridine, 4-cyanopyridine)

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Title:The Character of Low-Lying Excited States of Mixed-Ligand Metal Carbonyls. TD-DFT and CASSCF/CASPT2 Study of [W(CO)4L] (L = ethylenediamine, N,N'-dialkyl-1,4-diazabutadiene) and [W(CO)5L] (L = pyridine, 4-cyanopyridine)
Creators:
Záliš, Stanislav
Vlček, Antonín
Daniel, Chantal
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 68, 1, pp. 89-104
Uncontrolled Keywords:<i>Ab initio</i>, Charge transfer, Time-resolved infrared spectroscopy, Tungsten complexes, Complete active space SCF, DFT calculations, UV-VIS spectroscopy, Excited states, Time dependent density functional

Abstract

This contribution presents the results of the TD-DFT and CASSCF/CASPT2 calculations on [W(CO)<sub>4</sub>(MeDAB)] (MeDAB = <i>N</i>,<i>N'</i>-dimethyl-1,4-diazabutadiene), [W(CO)<sub>4</sub>(en)] (en = ethylenediamine), [W(CO)<sub>5</sub>(py)] (py = pyridine) and [W(CO)<sub>5</sub>(CNpy)] (CNpy = 4-cyanopyridine) complexes. Contrary to the textbook interpretation, calculations on the model complex [W(CO)<sub>4</sub>(MeDAB)] and [W(CO)<sub>5</sub>(CNpy)] show that the lowest W→MeDAB and W→CNpy MLCT excited states are immediately followed in energy by several W→CO MLCT states, instead of ligand-field (LF) states. The lowest-lying excited states of [W(CO)<sub>4</sub>(en)] system were characterized as W(CO<sub>eq</sub>)<sub>2</sub>→CO<sub>ax</sub> CT excitations, which involve a remarkable electron density redistribution between axial and equatorial CO ligands. [W(CO)<sub>5</sub>(py)] possesses closely-lying W→CO and W→py MLCT excited states. The calculated energies of these states are sensitive to the computational methodology used and can be easily influenced by a substitution effect. The calculated shifts of [W(CO)<sub>4</sub>(en)] stretching CO frequencies due to excitation are in agreement with picosecond time-resolved infrared spectroscopy experiments and confirm the occurrence of low-lying M→CO MLCT transitions. No LF electronic transitions were found for either of the complexes studied in the region up to 4 eV. <p>

Title:The Character of Low-Lying Excited States of Mixed-Ligand Metal Carbonyls. TD-DFT and CASSCF/CASPT2 Study of [W(CO)4L] (L = ethylenediamine, N,N'-dialkyl-1,4-diazabutadiene) and [W(CO)5L] (L = pyridine, 4-cyanopyridine)
Creators:
Záliš, Stanislav
Vlček, Antonín
Daniel, Chantal
Uncontrolled Keywords:<i>Ab initio</i>, Charge transfer, Time-resolved infrared spectroscopy, Tungsten complexes, Complete active space SCF, DFT calculations, UV-VIS spectroscopy, Excited states, Time dependent density functional
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:68
Number:1
Page Range:pp. 89-104
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc20030089UNSPECIFIED
ID Code:2048
Item Type:Article
Deposited On:06 Feb 2009 17:15
Last Modified:06 Feb 2009 16:15

Citation

Záliš, Stanislav; Vlček, Antonín; Daniel, Chantal (2003) The Character of Low-Lying Excited States of Mixed-Ligand Metal Carbonyls. TD-DFT and CASSCF/CASPT2 Study of [W(CO)4L] (L = ethylenediamine, N,N'-dialkyl-1,4-diazabutadiene) and [W(CO)5L] (L = pyridine, 4-cyanopyridine). Collection of Czechoslovak Chemical Communications, 68 (1). pp. 89-104. ISSN 0010-0765

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