Formation, electrochemical and radical scavenging properties of novel ruthenium compounds with N, X-donor (X = O, N) heterocyclic chelators

Herein, we communicate the formation of novel ruthenium compounds with N, X-donor (X = O, N) heterocyclic- derived ligands. A paramagnetic ruthenium(IV) complex, [RuCl(pho)(bzca)(PPh3)](1) (pho = 2- aminophenolate; bzca = 2-carboxylate-1H-benzimidazole) was isolated from the reaction of the ruthenium(II) precursor, trans-[RuCl2(PPh3)3] and 2-((1H-benzimidazole)methylamino)phenol (Hbzap). The 1:1 molar reaction between the same metal precursor and N-(benzoxazole)-2-hydroxybenzamide (H2bhb) led to the formation of cis-Cl, trans-P-[RuIII(Hbhb)Cl2(PPh3)2](2). The dinuclear ruthenium compounds, (l-Htba,Cl)2[RuIICl(PPh3)]2(3) (Htba = N-(thiophene)methyl-benzoxazole-2-amine) and (l-Cl)2[RuIIICl(Hchpr)(PPh3)]2(4) (H2chpr = 2-amino-3-((tetrahydro-2H-pyran-4-ylimino)methyl)-4Hchromen- 4-one) were formed from the equimolar ratio coordination reactions between trans- [RuCl2(PPh3)3] and the respective free-ligands, Htba and H2chpr. These metal complexes were characterized via IR-, NMR- and UV–Vis spectroscopy, molar conductivity measurements and structural elucidations were confirmed by single crystal X-ray analysis. The X-ray studies revealed that all the metallic compounds exhibited octahedral geometries and that the Hbzap free ligand has undergone a unique molecular transformation to afford the pho and bzca bidentate chelators in 1. The electrochemical properties of the respective metal complexes were investigated by voltammetric analysis. The cyclic voltammograms (CVs) of 1–3 showed one redox couple while within the CV of the dinuclear compound 4, two redox couples were observed. The ligands and their metal complexes were also subjected to DPPH radical scavenging studies. The IC50 values showed that all the metallic compounds have higher radical scavenging activities than their corresponding free-ligands and the natural antioxidant, Vitamin C

Ruthenium complexes with lumazine derivatives: structural, electrochemical, computational and radical scavenging studies

In this research study, the formation and characterization of new ruthenium(II) and (III) complexes encompassing multidentate ligands derived from 6-acetyl-1,3, 7-trimethyllumazine (almz) are reported. The 1:1 molar coordination reactions of trans-[RuCl2(PPh3)3] with N-1-[1,3, 7-trimethyllumazine]benzohydride (bzlmz) and 6-(N-methyloxime)- 1,3,7-trimethyllumazine (ohlmz) formed a diamagnetic ruthenium(II) complex, cis-[RuCl2(bzlmz)(PPh3)] (1), and paramagnetic complex, cis-[RuIIICl2(olmz)(PPh3)] (2) [Holmz = 6-(N-hydroxy-N0-methylamino)-1,3,7-trimethyllumazine], respectively. These ruthenium complexes were characterized via physico-chemical and spectroscopic methods. Structural elucidations of the metal complexes were confirmed using single crystal X-ray analysis. The redox properties of the metal complexes were investigated via cyclic voltammetry. Electron spin resonance spectroscopy confirmed the presence of a paramagnetic metal centre in 2. The radical scavenging activities of the metal complexes were explored towards the DPPH and NO radicals. Quantum calculations at the density functional theory level provided insight into the interpretation of the IR and UV–Vis experimental spectra of 1

Coordination of di- and triimine ligands at ruthenium(II) and ruthenium(III) centers: structural, electrochemical and radical scavenging studies

Herein, we explore the coordination of di- and triimine chelators at ruthenium(II) and ruthenium(III) centers. The reactions of 2,6-bis-((4- tetrahydropyranimino)methyl)pyridine (thppy), N1,N2-bis((3-chromone) methylene)benzene-1,2-diamine (chb), and tris-((1H-pyrrol-2-ylmethylene) ethane)amine (H3pym) with trans-[RuIICl2(PPh3)3] afforded the diamagnetic ruthenium(II) complex cis-[RuCl2(thppy)(PPh3)] (1) and the paramagnetic complexes [mer-Ru2(μ-chb)Cl6(PPh3)2] (2), and [Ru(pym)] (3), respectively. The complexes were characterized by IR, NMR, and UV–vis spectroscopy and molar conductivity measurements. The structures were confirmed by single crystal X-ray diffraction studies. The redox properties of the metal complexes were probed via cyclic- and squarewave voltammetry. Finally, the radical scavenging capabilities of the metal complexes towards the NO and 2,2-di(4-tert-octylphenyl)-1-picrylhydrazyl (DPPH) radicals were investigate

Ruthenium complexes with Schiff base ligands containing benz(othiazole/imidazole) moieties: Structural, electron spin resonance and electrochemistry studies

Novel ruthenium(II/III) complexes of Schiff bases containing benzimidazole (bz) or benzothiazole (bs) moieties were isolated: the diamagnetic ruthenium complex, cis-[RuIICl2(bzpy)(PPh3)2] (1) was formed from the 1:1 M reaction between N-((pyridine-2-yl)methylene)-1H-benzimidazole (bzpy) and metal precursor, trans-[RuCl2(PPh3)3]. The same metal precursor, when reacted with the benzimidazole-derived Schiff bases [N-(2-hydroxybenzylidene)-benzothiazole (Hbsp) and N-(2-hydroxybenzylidene)-benzimidazole (Hbzp)], afforded the paramagnetic ruthenium(III) complexes [RuCl(bsp)2(PPh3)] (2) and trans-[RuCl(bzp)(PPh3)2] (3), respectively. These metal complexes were characterized via IR, mass and UV–Vis spectroscopy, elemental analysis, single crystal XRD analysis as well as conductivity measurements. Their redox properties were probed by voltammetry and accompanying UV–Vis spectroelectrochemistry experiments. Structural features of complex 1 were further investigated by multinuclear (1H and 31P) NMR spectroscopy

6-Amino-1,3-dimethyl-5-[(E)-2-(methylsulfanyl)benzylideneamino]pyrimidine-2,4(1H,3H)-dione–1,3,7,9-tetramethylpyrimido[5,4-g]pteridine-2,4,6,8-tetrone (1/1)

In the title co-crystal, C12H12N6O4·C14H16N4O2S, both molecules are essentially planar [maximum deviations = 0.129 (1) and 0.097 (1) Å, respectively]. The tricyclic and Schiff base molecules are alternately stacked along the a axis and are linked by π–π interactions with centroid–centroid distances of 3.5170 (16) and 3.6576 (17) Å. An intramolecular C—H...O hydrogen bond and a C—H...S contact occur in the Schiff base molecule. In the crystal, N—H...O, N—H...N and C—H...O hydrogen bonds lead to the formation of a three-dimensional network

N-[(E)-Thiophen-2-ylmethylidene]-1,3-benzothiazol-2-amine

In the title thiophene-derived Schiff base compound, C12H8N2S2, the thiophene ring is slighty rotated from the benzothiazole group mean plane, giving a dihedral angle of 12.87 (6)°. The largest displacement of an atom in the molecule from the nine-atom mean plane defined by the non-H atoms of the benzothiazole ring system is 0.572 (1) Å, exhibited by the C atom at the 3-position of the thiophene ring. In the crystal, weak C—H...S hydrogen bonds involving the thiophene group S atom and the 4-position thiophene C—H group of a symmetry-related molecule lead to an infinite one-dimensional chain colinear with the c axis. The structure is further stabilized by π–π interactions; the distance between the thiazole ring centroid and the centroid of an adjacent benzene ring is 3.686 (1) Å. The crystal studied was an inversion twin with the ratio of components 0.73 (3):0.27 (3)