Spectroscopic characterization of chloride and pseudohalide ruthenium(II) complexes with 4-(4-nitrobenzyl)pyridine

Abstract

Chloride, isocyanate and isothiocyanate hydride carbonyl ruthenium(II) complexes of 4-(4-nitrobenzyl)pyridine were synthesized from the precursor complex [RuHCl(CO)(PPh 3 ) 3 ] and characterized by IR, NMR, UV-Vis spectroscopy and X-ray crystallography. The electronic structures of the complexes were investigated by means of DFT calculations, based on their crystal structures. The spinallowed singlet-singlet electronic transitions of the complexes were calculated by time-dependent DFT, and the UVVis spectra are discussed on this basis. The emission properties of the complexes were studied at ambient temperature, and the quantum yields of fluorescence, the lifetimes and nature of the excited states are discussed. The chloride and isothiocyanate complexes are practically nonemissive, with quantum yields under 0.01 %. Interpretation of spectra, supported by TD-DFT calculations, indicates that in this energy region, the transitions have MLCT character with admixture of LLCT (chloride and isothiocyanate complexes). The dominant LLCT character was visible in the case of the most emissive (isocyanate) complex. The low values of the lifetimes and quantum yields for these complexes indicate the influence of the metal center in the emission process.

Synthesis, characterization, and evaluation of biological activities of new 4′‐substituted ruthenium (II) terpyridine complexes: Prospective anti‐inflammatory properties

“…This red‐shift of absorption bands indicates a distribution of the 4 d Ru energy levels in complex 11 over a wider energy range compared with complex 9 , due to overlapping with orbitals centered on the isothiocyanate (NCS) ligand. [ 48 ] Moreover, the absorption bands found at wavelengths shorter than 400 nm are assigned to the intraligand (π–π*) charge transitions of the tpy and conjugated ancillary ligands.…”

Li4Ru2OCl10·10H2O: crystal structure, magnetic properties and bonding interactions in ruthenium-oxo complexes

“…The high-energy, high-intensity peak arising with a maximum around 245 nm can be attributed to the to * type transition of Ru-Cl. On the other hand, the absorption peak observed around 400 nm can be assigned to the metal to ligand charge transfer transitions (Maroń & Małecki, 2014;Ishiyama, 1969). The shoulder peak observed around 500 nm may possibly be from Ru-O-Ru chromophore (San Filippo et al, 1977).…”