Detection of Indistinct Fe-N Stretching Bands in Iron(V) Nitrides by Photodissociation Spectroscopy

0485420 - ÚFCH JH 2019 RIV DE eng J - Journal Article
Andris, E. - Navrátil, R. - Jašík, J. - Sabenya, G. - Costas, M. - Srnec, Martin - Roithová, J.
Detection of Indistinct Fe-N Stretching Bands in Iron(V) Nitrides by Photodissociation Spectroscopy.
Chemistry - A European Journal. Roč. 24, č. 20 (2018), s. 5078-5081. ISSN 0947-6539. E-ISSN 1521-3765
R&D Projects: GA ČR(CZ) GJ15-10279Y
Institutional support: RVO:61388955
Keywords : photodissociation spectrochemistry * infrared spectra * DFT
OECD category: Physical chemistry
Impact factor: 5.160, year: 2018

We report for the first time infrared spectra of three non-heme pseudo-octahedral iron(V) nitride complexes with assigned Fe-N stretching vibrations. The intensities of the Fe-N bands in two of the complexes are extremely weak. Their detection was enabled by the high resolution and sensitivity of the experiments performed at 3K for isolated complexes in the gas phase. Multireference CASPT2 calculations revealed that the Fe-N bond in the ground doublet state is influenced by two low-lying excited doublet states. In particular, configuration interaction between the ground and the second excited state leads to avoided crossing of their potential energy surfaces along the Fe-N coordinate, which thus affects the ground-state Fe-N stretching frequency and intensity. Therefore, DFT calculated Fe-N stretching frequency strongly depends on the amount of Hartree-Fock exchange potential. As a result, by tuning the amount of Hartree-Fock exchange potential in the B3LYP functional, it was possible to obtain theoretical spectra perfectly consistent with the experimental data. The theory shows that the intensity of the Fe-N stretching vibration can almost vanish due to strong coupling with other stretching modes of the ligands.
Permanent Link: http://hdl.handle.net/11104/0280444