TY - JOUR

T1 - A Comparative XPS, UV PES, NEXAFS, and DFT Study of the Electronic Structure of the Salen Ligand in the H2(Salen) Molecule and the [Ni(Salen)] Complex

AU - Korusenko, Petr M.

AU - Petrova, Olga V.

AU - Vereshchagin, Anatoliy A.

AU - Katin, Konstantin P.

AU - Levin, Oleg V.

AU - Nekipelov, Sergey V.

AU - Sivkov, Danil V.

AU - Sivkov, Victor N.

AU - Vinogradov, Alexander S.

PY - 2023/6/7

Y1 - 2023/6/7

N2 - A comparative study of the electronic structure of the salen ligand in the H 2(Salen) molecule and the [Ni(Salen)] complex was performed using the experimental methods of XPS, UV PES, and NEXAFS spectroscopy along with DFT calculations. Significant chemical shifts of +1.0 eV (carbon), +1.9 eV (nitrogen), and -0.4 eV (oxygen) were observed in the 1s PE spectra of the salen ligand atoms when passing from a molecule to a complex, unambiguously indicating a substantial redistribution of the valence electron density between these atoms. It is proposed that the electron density transfer to the O atoms in [Ni(Salen)] occurred not only from the Ni atom, but also from the N and C atoms. This process seemed to be realized through the delocalized conjugated π-system of the phenol C 2p electronic states of the ligand molecule. The DFT calculations (total and partial DOS) for the valence band H 2(Salen) and [Ni(Salen)] described well the spectral shape of the UV PE spectra of both compounds and confirmed their experimental identification. An analysis of the N and O 1s NEXAFS spectra clearly indicated that the atomic structure of the ethylenediamine and phenol fragments was retained upon passing from the free salen ligand to the nickel complex.

AB - A comparative study of the electronic structure of the salen ligand in the H 2(Salen) molecule and the [Ni(Salen)] complex was performed using the experimental methods of XPS, UV PES, and NEXAFS spectroscopy along with DFT calculations. Significant chemical shifts of +1.0 eV (carbon), +1.9 eV (nitrogen), and -0.4 eV (oxygen) were observed in the 1s PE spectra of the salen ligand atoms when passing from a molecule to a complex, unambiguously indicating a substantial redistribution of the valence electron density between these atoms. It is proposed that the electron density transfer to the O atoms in [Ni(Salen)] occurred not only from the Ni atom, but also from the N and C atoms. This process seemed to be realized through the delocalized conjugated π-system of the phenol C 2p electronic states of the ligand molecule. The DFT calculations (total and partial DOS) for the valence band H 2(Salen) and [Ni(Salen)] described well the spectral shape of the UV PE spectra of both compounds and confirmed their experimental identification. An analysis of the N and O 1s NEXAFS spectra clearly indicated that the atomic structure of the ethylenediamine and phenol fragments was retained upon passing from the free salen ligand to the nickel complex.

KW - H2(Salen) molecule (C16H16N2O2)

KW - [Ni(Salen)] complex (NiO2N2C16H14)

KW - X-ray photoemission (XPS) and ultraviolet photoemission spectroscopy (UV PES)

KW - X-ray absorption fine structure (NEXAFS) spectroscopy

KW - density-functional theory (DFT) calculations

KW - electronic structure calculations

KW - Ligands

KW - Ethylenediamines/chemistry

KW - Electron Transport

KW - Nickel/chemistry

UR - https://www.mendeley.com/catalogue/041d088d-90a0-318d-9ab6-8994e8bb4989/

U2 - 10.3390/ijms24129868

DO - 10.3390/ijms24129868

M3 - Article

C2 - 37373016

VL - 24

JO - International Journal of Molecular Sciences

JF - International Journal of Molecular Sciences

SN - 1422-0067

IS - 12

M1 - 9868

ER -