Molecular and spectroscopic properties of hydridecarbonyl ruthenium complexes with pyrazine carboxylic acid ligands

The hydride carbonyl ruthenium(II) [RuH(CO)(pyzCOO)(PPh3)2] (1), [RuH(CO)(pyz-2,3-COO[CH3])(PPh3)2]·H2O (2) and dinuclear Ru(II)/Ru(III) [RuH(CO)(PPh3)(pyz-2,3-COO)Ru(CO)Cl2(PPh3)2] (3) complexes were synthesized and characterized by IR, 1H, 31P NMR, UV–Vis spectroscopy and X-ray crystallography. The experimental studies were complemented by quantum chemical calculations, which were used to identify the nature of the interactions between the ligands and the central ion, and the orbital composition in the frontier electronic structure. Based on a molecular orbital scheme, the calculated results allowed the interpretation of the UV–Vis spectra obtained at an experimental level. The luminescence property of the complex 2 was determined. The ac magnetic susceptibility measurements showed a residual magnetism evidenced by the small values of the molar susceptibility, not exceeding 0.5 emu/mol at 2 K, a lack of a Curie-Weiss region and weak magnetic interactions below 20 K.

Graphical abstractThe hydride carbonyl ruthenium(II) [RuH(CO)(pyzCOO)(PPh3)2] (1), [RuH(CO)(pyz-2,3-COO[CH3])(P-Ph3)2].H2O (2) and dinuclear Ru(II)/Ru(III) [RuH(CO)(PPh3)(pyz-2,3-COO)Ru(CO)Cl2(PPh3)2] (3) complexes were synthesized and characterized by IR, 1H, 31P NMR, UV–Vis spectroscopy and X-ray crystallography. The experimental studies were complemented by quantum chemical calculations, which were used to identify the nature of the interactions between the ligands and the central ion, and the orbital composition in the frontier electronic structure. Based on a molecular orbital scheme, the calculated results allowed the interpretation of the UV–Vis spectra obtained at an experimental level. The luminescence property of the complex 2 was determined. The ac magnetic susceptibility measurements showed a residual magnetism evidenced by the small values of the molar susceptibility, not exceeding 0.5 emu/mol at 2 K, a lack of a Curie-Weiss region and weak magnetic interactions below 20 K.Figure optionsDownload full-size imageDownload as PowerPoint slide