Luminescent azide and thiocyanate phosphine complexes of ruthenium(II) with acetonitrile as co-ligand

The studies on synthesis and characterization of ruthenium complexes have received considerable recent attention, owing to their interesting photophysical and photochemical properties. Luminescent ruthenium(II) complexes, especially with polypyridyl type ligands, have been extensively studied in application in photochemical molecular devices. However, phosphine complexes of ruthenium(II) based on [RuCl2(PPh3)3] and [RuHCl(CO)(PPh3)3], which recently were widely studied as effective and selective catalysts in organic synthesis, are much less studied as luminofors and are still of interest for their potential applications. Due to this fact studies on the synthesis, and spectroscopic, electrochemical properties of [RuH(X)(MeCN)(CO)(PPh3)2] and [Ru(X)2(MeCN)(PPh3)2] (where X = N3−, NCS−) are important basis in description of luminescent properties of phosphine ruthenium(II) complexes. This paper present the synthesis and characterization by IR, NMR, UV-Vis spectroscopy, X-ray crystallography and electrochemical studies (CV, DPV) of four ruthenium(II) complexes with formulas [RuH(X)(MeCN)(CO)(PPh3)2] and [Ru(X)2(MeCN)(PPh3)2] (where X = N3−, NCS−). The emission properties of the complexes were studied in ambient and low temperature. The quantum yields of fluorescence, the lifetimes and the nature of excited states were discussed based on molecular properties. To elucidate the structural, spectroscopic and bonding properties of obtained complexes, calculations at the DFT level were undertaken. The received azide and thiocyanate analogs of precursor complexes, [RuHCl(CO)(PPh3)3] and [RuCl2(PPh3)3], exhibit luminescence properties at ambient temperature as well as at the temperature of liquid nitrogen (77 K). The emission spectra, the decay times, the quantum yields of luminescence in correlation with electrochemistry and quantum-mechanical calculations indicate that, in the creation of excited states of the complexes engaged are both the metal d orbitals and pseudohalide ligands orbitals.