title: Ligand effects on structures and spectroscopic properties of pyridine-2-aldoxime complexes of Re(CO)3(+): DFT/TDDFT theoretical studies.
abstract: The series of novel rhenium(I) tricarbonyl mixed-ligand complexes Re(X)(CO)(3)(N^N) (N^N = pyridine-2-aldoxime; X = -Cl, 1; X = -CN, 2; and X = -C≡C, 3) has been investigated theoretically to explore the ligand X effect on their electronic structures and spectroscopic properties. The contribution of the X ligand to the highest occupied molecular orbital (HOMO) and HOMO-1 decreases in the order of 3 > 1 > 2, in line with the π-donating abilities of the X: -C≡C > -Cl > -CN. The reorganization energy (λ) calculations show that 1 and 3 will result in the higher efficiency of organic light-emitting diodes than 2. The lowest-lying absorptions of 1 and 3 can be assigned to the {[d(xz), d(yz)(Re) + π(CO) + π(X)] → [π* (N^N)]} transition with mixing metal-to-ligand, ligand-to-ligand, and X ligand-to-ligand charge transfer (MLCT/LLCT/XLCT) character, whereas this absorption at 354 nm (H-1 → L) of 2 is assigned to {[d(xz), d(yz)(Re) + π(CO) + π(N^N)] → [π* (N^N)]} transition with MLCT/LLCT/ILCT (intraligand charge transfer). Furthermore, the absorptions are red-shifted in the order 2, 1, and 3, with the increase of π-donating abilities of X ligands. The solvent effects cause red shifts of the absorption and emission spectra with decreasing solvent polarity.
authors.affiliation: School of Chemistry and Materials Science, Shanxi Normal University, Linfen, 041004, China.
authors.forename: Ting-Ting
authors.initials: TT
authors.lastname: Zhang
authors.forename: Jian-Feng
authors.initials: JF
authors.lastname: Jia
authors.forename: Ying
authors.initials: Y
authors.lastname: Ren
authors.forename: Hai-Shun
authors.initials: HS
authors.lastname: Wu
mesh_terms: D008024:Ligands; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010091:Oximes / Q000737:chemistry*; D011789:Quantum Theory; D012211:Rhenium / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D008024:Ligands; D009942:Organometallic Compounds; D010091:Oximes; D012211:Rhenium; C060977:pyridine-2-aldoxime