Author, as appears in the article.: De Graaf, C. ; Saure, S.

Department: Química Física i Inorgànica

URV's Author/s: DE GRAAF , CORNELIS; Saure, S.

Keywords: TD-DFT Fe(III) Complexes Light induced spin cross over

Abstract: Two light-induced spin-crossover Fe(III) compounds have been studied with time-dependent density functional theory (TD-DFT) to investigate the deactivation mechanism and the role of the ligand-eld states as intermediates in this process. The B3LYP* functional has previously shown its ability to accurately describe (light-induced) spin-crossover inFe(II) complexes. Here, we establish its performance for Fe(III) systems using [Fe(qsal)2]+(Hqsal=2-[(8-quinolinylimino)methyl] phenol) and [Fe(pap)2]+ (Hpap=2-(2-pyridylmethyleneamino)phenol) as test cases comparing the B3LYP* results to experimental information and to multicongurational wave function results. In addition to rather accurate high spin (HS) and low spin (LS) state geometries, B3LYP* also predicts ligand-to-metal charge transfer (LMCT) states with large oscillator strength in the energy range where the UV-VIS spectrum shows an intense absorption band, whereas optically allowed - excitations on the ligands were calculated at higher energy. Subsequently, we have generated a two-dimensional potential energy surface of the HS and LS states varying the Fe-N and Fe-O distances. LMCT and metal centered (MC) excited states were followed along the approximate minimal energy path that connects the minima of the HS and LS on this surface. The 2LMCT state has a minimum in the same region as the initial LS state, where we also observe a crossing with the intermediate spin (IS) state. Upon the expansion of the coordination sphere of the Fe(III) ion, the IS state crosses with the HS state and further expansion of the coordination sphere leads to the excited spin state trapping as observed in experiment. The calculation of the intersystem crossing rates reveals that the deactivation from 2LMCT!IS!HS competes with the 2LMCT!IS!LS pathway, in line with the low eciency encountered in experiments.

Research group: Química Quàntica

Thematic Areas: Química Química Chemistry

licence for use: https://creativecommons.org/licenses/by/3.0/es/

ISSN: 1463-9076

Author identifier: 0000-0001-8114-6658;

Record's date: 2018-02-28

Last page: 1244

Papper version: info:eu-repo/semantics/submittedVersion

Link to the original source: http://pubs.rsc.org/en/content/articlelanding/2016/cp/c5cp06620d#!divAbstract

Funding program: plan; Excelencia; CTQ2014-51938-P altres; Grupos Consolidados; 2014SGR199 altres; Xarxa d'R+D+I en Qumica Teorica i Computacional; XRQTC european; COST Action ECOSTBio; CM1305

Article's DOI: 10.1039/C5CP06620D

Entity: Universitat Rovira i Virgili

Journal publication year: 2016

First page: 1233

Publication Type: Article Artículo Article