Formation of Ruthenium Nitrosyl Complexes:  Reactions of Ru(bpy)(CO)₂Cl₂and Its Methyl-Substituted Analogues Ru(4,4‘-dmbpy)(CO)₂Cl₂and Ru(6,6‘-dmbpy)(CO)₂Cl₂in Oxidizing Acidic Solutions

Abstract

Experimental SectionMaterials. [Ru(CO)3Cl2]2 was purchased from Johnson & Matthey, and 2,2′-bipyridine and 4,4′-dimethyl-2,2′-bipyridine from were purchased Aldrich Chemicals. 6,6′-Dimethyl-2,2′-bipyridine was obtained from the University of Oulu, where it was synthesized according to the literature method. 16 Ru(bpy)(CO)2Cl2 and its dimethyl-substituted analogues were synthesized from [Ru(CO) 3Cl2]2 and 2,2′-bipyridine reagents by refluxing in THF as described earlier. 17,18 HNO3 (65%, J. T. Baker) and HCl (37%, Merck) were of analytical grade and were used as received. Ligand substitution reactions were carried out in a Berghof 60 mL digestive pressure bomb with a PTFE liner. 19 All manipulations were performed in air.Characterization of the Products. Infrared spectra were measured with a Nicolet Magna FTIR spectrometer 750. X-ray diffraction data were collected with a Nicolet R3m or Syntex P21 diffractometer using graphite-monochromatized Mo KR radiation (λ ) 0.710 73 Å). Cell parameters were obtained from 25 automatically centered reflections. Intensities were corrected for background, polarization, and Lorentz effects. Data collection, data reduction, and cell refinement were carried out with the P3/P4-Diffractometer Program V 4.27. 20 The structures were solved by direct methods. The structure solution was carried out with the SHELXS 86 program and the structure refinement with the SHELXL 93 program. 21,22 All non-hydrogen atoms, except one of the NO 3 -oxygens in 3, were refined anisotropically. The NO3 -oxygen was disordered in two positions with an equal occupation factor (0.5) and refined isotropically. All hydrogens in 1, 2, and 4 were located from the difference Fourier map and refined isotropically with a fixed isotropic displacement parameter (U ) 0.08 Å 2 for uncoordinated H2O hydrogens in 2 and U ) 0.05 Å 2 for all other hydrogens). The hydrogens of the H 2O ligand in 3 and those of the H3O + ions in (H3O)2-[Ru(NO)Cl 5] could not be located from the difference Fourier map and were therefore omitted. Both oxygens of the H 3O + ions in (H3O)2-[Ru(NO)Cl 5] were surrounded by nine chlorines of the [RuCl5(NO)]2anions in the range 3.32-3.65 Å, allowing weak interactions and several orientations of the H 3O + ions. The crystallographic data are collected in Table 1. Formation of Ru(dcbpy)Cl 3(NO) (1) (dcbpy ) 4,4′-Dicarboxy-2,2′-bipyridine).A 50 mg sample of Ru(4,4′-dmbpy)(CO) 2Cl2, 4 mL of hydrochloric acid (37%), and 50 µL of nitric acid (65%) were introduced into a 60 mL Berghof pressure vessel. The reaction mixture was heated to 240°C (temperature was maintained at 240°C for 2.5 h) and cooled slowly to room temperature (cooling rate about 16°C/ h). Dark red crystals (15.4 mg) formed during the cooling period were separated from the red solution by filtration and dried in air. The solid product was analyzed by X-ray diffraction and IR spectroscopic measurements as well as by elemental analysis. Anal. Calcd for 1: C, 29.95; N, 8.74; H, 1.68. Found: C, 30.05; N, 8.46; H, 1.59. IR (in KBr): ν(NO) 1912 ...

New Dicarboxylic Acid Bipyridine Ligand for Ruthenium Polypyridyl Sensitization of TiO2

“…Scheme provides a side-on view of the Ru­(bpy), Ru­(dcb), and Ru­(dfm) fragments taken from the crystal structures of [Ru­(bpy) 3 ] 2+ , [Ru­(bpy) 2 (dcb)] 2+ , and [Ru­(bpy) 2 (dfm)] 2+ , respectively. The larger dihedral angle between the two pyridine rings of dcb relative to bpy in Scheme was particular to these specific compounds and was not significant in a review of 11 crystal structures of ruthenium compounds with 17 coordinated dcb ligands. − The dihedral angles ranged between 0.6 and 13 degrees for coordinated dcb and bpy ligands. The bridging olefin in the 3 and 3′ positions of dfm maintains planarity of the two pyridyl rings while a significant change in the out-of plane orientation of the oxygen atoms of the carboxylic acid groups in dfm relative to dcb was clearly observed.…”

Coordination and Organometallic Chemistry of Metal−NO Complexes

“…Ru(NO)X 3 L 2 complexes can also be generated by other synthetic methodologies. For instance, Ru(CO) 2 (bipy)Cl 2 reacts with nitric acid in HX (X = Cl, F) to form fac - and mer -Ru(NO)X 2 Cl(bipy), the trichloro members of which have been structurally characterized. − The related Ru(NO)Cl 3 (PPh 3 ) 2 reacts with H 2 [S 2 N 2 H 2 ] [S 2 N 2 H 2 = 1,2-ethanediamine- N , N ‘ -bis(2-benzenethiolate)] to produce either [Ru(NO)(PPh 3 )(S 2 N 2 H 2 )]Cl or the thiolate-bridged bimetallic [Ru(NO)(S 2 N 2 H)] 2 depending on the pH of the reaction mixture. As shown in Scheme , [Ru(NO)(S 2 N 2 H)] 2 can be converted to [Ru(NO)(PPh 3 )(S 2 N 2 H)] + by the addition of PPh 3 under acidic conditions …”

“…For instance, Ru(CO) 2 -(bipy)Cl 2 reacts with nitric acid in HX (X ) Cl, F) to form fac-and mer-Ru(NO)X 2 Cl(bipy), the trichloro members of which have been structurally characterized. [873][874][875] The related Ru(NO)Cl 876 Ru(NO)Cl 3 (PPh 3 ) 2 also reacts with 1,2-dithiolatobenzene (S 2 2-) to form square pyramidal anionic complexes of the form [Ru(NO)(S 2 ) 2 ] -. As illustrated in Scheme 21, further reaction with (BrC 2 H 4 ) 2 S leads to template alkylation across a thiolate linkage of each S 2 moiety and the formation of an η 5 -dithiolatetrisulfur donor ligand (S 5 2-) in the octahedral [Ru-(NO)(S 5 )] + complex.…”

Redox and photochemical behaviour of ruthenium(II) complexes with H2dcbpy ligand (H2dcbpy = 2,2′-bipyridine-4,4′-dicarboxylic acid)

“…11 Only few ruthenium() 2,2Ј-bipyridine-4,4Ј-dicarboxylic acid complexes have been characterised by single-crystal X-ray diffraction measurements. Examples of these are Ru(H 2 dcbpy)-Cl 3 (NO) 14 and Ru(dcbpy) 2 (NCS) 2 . 15 We present herein the crystal structures of complexes 1 and 3-5.…”