Thioamide Ligands Research Articles

Synthesis of 2-substituted quinoline derivatives using [RuCl2(p-cymene)]2-ferrocene thioamide catalytic system via acceptorless dehydrogenative coupling

The substituted quinolines were synthesized via acceptorless dehydrogenative coupling (ADC) of 2-aminobenzyl alcohol with ketones/secondary alcohols, which was accomplished using the in situ catalytic activity of [RuCl2(p-cymene)]2 and ferrocene thioamide (Fc-TA) ligands. The catalysis was extended to aromatic and heterocyclic ketones and secondary alcohols, with unsubstituted and chloro‑substituted 2-aminobenzyl alcohols. The Fc-TA ligands (L1-L3) were synthesized, and characterized using spectroscopic techniques such as FT-IR, UV–Vis, NMR and HRMS. The influence of ligands on the catalysis was studied. Overall, the synthesis of quinolines was accomplished with good to moderate yields, via both mono and double dehydrogenation reactions along with hydrogen and water as only by-products.

Palladium(II) O^S thioamide complexes catalyzed Guerbet type reaction: β-Alkylation of cyclohexanol with primary alcohols

Pd(II)-PPh3 complexes containing salicylaldehyde based thioamide ligands (1–3) have been synthesized and characterized by analytical and spectroscopic (FT-IR, UV–Visible, HR-MS and NMR) techniques. Spectroscopic methods revealed square planar geometry for all the complexes. These complexes were tested as catalysts for Guerbet-type reaction i.e. dialkylation of cyclohexanol with primary alcohols. The reaction conditions were optimized. Complex 1 bearing morpholinyl group emerged as the best catalyst, and it was used for extending the scope of the reaction to several substituted primary alcohols. The dialkylated products were isolated using column chromatography and confirmed using GC–MS and 1H NMR spectroscopy.

Solid-state 31 P and 109 Ag CP/MAS NMR as a powerful tool for studying of silver(I) complexes with N-thiophosphorylated thiourea and thioamide ligands.

A family of three- and four-coordinated silver(I) complexes of formulas [Ag(PPh3 )2 L], [Ag(PPh3 )L], and [AgL]n with N-thiophosphorylated thiourea and thioamide ligands of general formula RC(S)NHP(S)(OPri)2 [R = Ph, PhNH, iPrNH, tBuNH, NH2 ] have been studied by solid-state 109 Ag and 31 P CPMAS NMR spectroscopy. 109 Ag NMR spectra have provided valuable structural information about Ag coordination, which is in good accordance with the available crystal structure data. The data presented in this work represent a significant addition to the available 109 Ag chemical shifts and chemical shifts anisotropies. The silver chemical shift ranges for different P,S-environments and coordination state were discussed in detail. The 1 J(31 P-107/109 Ag) and 2 J(31 P-31 P) values were determined and analyzed.

Half-sandwich Ru(II)-thioamide complexes as catalysts for one pot synthesis of aromatic 1,5-diketones

Four Ru(II)-arene thioamide complexes of the type [(η6-cymene)Ru(PPh3)(L)]+ (L = bidentate monoanionic thioamide ligand) have been synthesized and isolated as their hexafluorophosphate salts. All these complexes are fully characterized by spectroscopic methods. Molecular structures of the ligands (HL2 and HL3) and complex (3) were determined by single crystal X-ray crystallography. The ligands coordinated to Ru center through phenolic O and thioamide S atoms. All the four complexes were tested as catalysts in the one pot synthesis of 1,5-diketones from aromatic ketones and alcohols in the presence of KOtBu, and the products were analyzed by GC/GC–MS/1H NMR. Complexes 1 and 2 behaved as catalysts to produce 1,5-diketones while complexes 3 and 4 catalyzed the reactions to form alkylated ketones. Scope of the reaction was extended to various substituted alcohols and ketones to prepare 1,5-diketones with catalyst 1.

Silver(I) complexes bearing heterocyclic thioamide ligands with NH2 and CF3 substituents: effect of ligand group substitution on antibacterial and anticancer properties.

In recent years, there has been an increasing interest in the study of Ag(I) coordination compounds as potent antibacterial and anticancer agents. Herein, a series of Ag(I) complexes bearing phosphines and heterocyclic thioamide ligands with highly electronegative NH2- and CF3-group substituents, i.e. [AgCl(atdztH)(xantphos)] (1), [Ag(μ-atdztH)(DPEphos)]2(NO3)2 (2), [Ag(atdzt)(PPh3)3] (3), [Ag(μ-atdzt)(DPEphos)]2 (4), and [Ag(μ-mtft)(DPEphos)]2 (5), where atdztH = 5-amino-1,3,4-thiadiazole-2-thiol, mtftH = 4-methyl-5-(trifluoromethyl)-1,2,4-triazol-3-thiol, xantphos = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene, and DPEphos = bis(2-diphenylphosphino-phenyl)ether, were synthesized, and their in vitro antibacterial and anticancer properties were evaluated. Complexes 1-4 bearing the NH2-substituted thioamide exhibited moderate-to-high activity against S. aureus, B. subtilis, B. cereus and E. coli bacterial strains. A high antiproliferative activity was also observed for 1-3 against SKOV-3, Hup-T3, DMS114 and PC3 cancer cell lines (IC50 = 4.0-11.7 μM), as well as some degree of selectivity against MRC-5 normal cells. Interestingly, 5 bearing the CF3-substituted thioamide is completely inactive in all bioactivity studies. Binding of 1-3 to drug-carrier proteins BSA and HSA is reasonably strong for their uptake and subsequent release to possible target sites. The three complexes show a significant in vitro antioxidant ability for scavenging free radicals, suggesting likely implication of this property in the mechanism of their bioactivity, but a low potential to destroy the double-strand structure of CT-DNA by intercalation. Complementary insights into possible bioactivity mechanisms were provided by molecular docking calculations, exploring the ability of complexes to bind to bacterial DNA gyrase, and to the overexpressed in the aforementioned cancer cells Fibroblast Growth Factor Receptor 1, affecting their functionalities.

Biocompatible silver(I) complexes with heterocyclic thioamide ligands for selective killing of cancer cells and high antimicrobial activity – A combined in vitro and in silico study

A series of heteroleptic Ag(I) complexes bearing 4,6-dimethyl-2-pyrimidinethiol (dmp2SH), i.e., [AgCl(dmp2SH)(PPh3)2] (1), [Ag(dmp2SH)(PPh3)2]NO3 (2), [Ag(dmp2SΗ)(xantphos)]NO3 (3), [Ag(μ-dmp2S)(PPh3)]2 (4), [Ag(dmp2S)(xantphos)] (5), [Ag(μ-dmp2S)(DPEphos)]2 (6) (xantphos = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene and DPEPhos = bis[(2-diphenylphosphino)phenyl]ether) were synthesized. The complexes display systematic variation of particular structural characteristics which were proved to have a significant impact on their in vitro cytotoxicity and antimicrobial properties. A moderate-to-high potential for bacteria growth inhibition was observed for all complexes, with 2, 3 and 5 being particularly effective against Gram-(+) bacteria (IC50 = 1.6–4.5 μM). The three complexes exhibit high in vitro cytotoxicity against HeLa and MCF-7 cancer cells (IC50 = 0.32–3.00 μΜ), suggesting the importance of coordination unsaturation and cationic charge for effective bioactivity. A very low cytotoxicity against HDFa normal cells was observed, revealing a high degree of selectivity (selectivity index ~10) and, hence, biocompatibility. Fluorescence microscopy using 2 showed effective targeting on the membrane of the HeLa cancer cells, subsequently inducing cell death. Binding of the complexes to serum albumin proteins is reasonably strong for potential uptake and subsequent release to target sites. A moderate in vitro antioxidant capacity for free radicals scavenging was observed and a low potential to destroy the double-strand structure of calf-thymus DNA by intercalation, suggesting likely implication of these properties in the bioactivity mechanisms of these complexes. Further insight into possible mechanisms of bioactivity was obtained by molecular modeling calculations, by exploring their ability to act as potential inhibitors of DNA-gyrase, human estrogen receptor alpha, human cyclin-dependent kinase 6, and human papillomavirus E6 oncoprotein.

Hybrid Palladium Catalyst Assembled from Chiral Phosphoric Acid and Thioamide for Enantioselective β‐C(sp3)−H Arylation

AbstractA hybrid palladium catalyst assembled from a chiral phosphoric acid (CPA) and thioamide enables a highly efficient and enantioselective β‐C(sp3)−H functionalization of thioamides (up to 99 % yield, 97 % ee). A kinetic resolution of unsymmetrical thioamides by intermolecular C(sp3)−H arylation can be achieved with high s‐factors. Mechanistic investigations have revealed that stereocontrol is achieved by embedding the substrate in a robust chiral cavity defined by the bulky CPA and a neutral thioamide ligand.

Hybrid Palladium Catalyst Assembled from Chiral Phosphoric Acid and Thioamide for Enantioselective β-C(sp3 )-H Arylation.

A hybrid palladium catalyst assembled from a chiral phosphoric acid (CPA) and thioamide enables a highly efficient and enantioselective β-C(sp3 )-H functionalization of thioamides (up to 99 % yield, 97 % ee). A kinetic resolution of unsymmetrical thioamides by intermolecular C(sp3 )-H arylation can be achieved with high s-factors. Mechanistic investigations have revealed that stereocontrol is achieved by embedding the substrate in a robust chiral cavity defined by the bulky CPA and a neutral thioamide ligand.

Two Cu(II) and Co(II)-based coordination polymers based on the N,S-mixed donor ligand: structural characterization and anti-endometrial cancer activity

In this study, two new coordination polymers based on Cu(II) and Co(II) ions as the metal nodes, {Cu(3-PPT)2]·H2O}n (1) and {[Co(3-PPT)2]·3CH3OH·H2O}n (2), have been successfully constructed from a pyridine-substituted N-heterocyclic thioamide ligand, namely 3-HPPT (3-HPPT = 4-(3-pyridinyl)-pyrimidine-2-thiol). Furthermore, the treatment activity of complexes 1–2 against HEC-1 endometrial cancer cells was evaluated. First, the CCK-8 assay was performed and the inhibitory effect of compounds 1–2 on HEC-1 cells were determined. Then, the Annexin V-FITC/PI method was performed and the induction activity of the compounds on the cancer cell apoptosis was evaluated. Finally, the PI3K/AKT pathway activation was also measured with western blot.

Pyrrole thioamide complexes of organo-rhodium(III), -iridium(III) and -ruthenium(II)

Reactions of the pentamethylcyclopentadienyl complexes [(η5-Cp*)MCl2]2 (M = Rh, Ir) and the ruthenium arene complex [(η6-C6Me6)RuCl2]2 with pyrrole-2-thioamide ligands (containing various substituents on the pyrrole ring) and triethylamine base were investigated. A set of new dinuclear complexes were obtained in which the pyrrole thioamide ligand bonds as a dianion, through the deprotonated pyrrole, and the sulfur atom bridging the two metal centres, as confirmed by a X-ray structure determination on an iridium derivative. When triphenylphosphine was included in the reaction mixture, mononuclear complexes were obtained, with the pyrrole thioamide dianion ligand coordinating through sulfur and the pyrrole nitrogen, forming a five-membered chelate ring. The complexes were characterised by NMR and IR spectroscopies, and ESI mass spectrometry. A preliminary investigation of the activity of a selection of compounds towards A549 (adenocarcinomic human alveolar basal epithelial) cells was also carried out.

Novel Hybrid Thioamide Ligand Supported Copper Nanoparticles on SBA-15: A Copper Rich Robust Nanoreactor for Green Synthesis of Triazoles and Tetrazoles in Water Medium

In this work, a new thioamide based ligand with reductive nature was designed for modification of mesoporous SBA-15. For this purpose, the channels of SBA-15 were modified with Tris(2-aminoethyl)amine (TAEA) groups and then reacted with S8 and phenyl acetylene to form thioamide groups via Willgerodt-Kindler reaction. This porous material proved to be an effective host for the immobilization of inexpensive Cu(II) ions. The catalytically active Cu(I) species were generated automatically due to the reductive nature of thioamide modified surface of catalyst without use of any toxic reducing agents. The well stabilized Cu(I) species into the nano-channels of SBA-15 were used for synthesis of various triazoles from sodium azide, phenyl acetylene and alkyl/benzyl halides or alkyl epoxides and various tetrazoles from sodium azide and aryl/alkyl nitriles under green mild aqueous reaction conditions. This catalytic system was used for 9 and 11 consecutive runs for synthesis of triazoles and tetrazoles, respectively.

Pyrrole thioamide complexes of the d8 metals platinum(II), palladium(II) and gold(III)

Reactions of the cycloaurated gold(III) complexes [AuCl2(2-benzylpyridyl)] and [AuCl2(C6H4CH2NMe2)] with a set of pyrrole-2-thioamide ligands, containing various substituents on the pyrrole ring, gave a series of new gold(III) pyrrole thioamide complexes. X-ray crystal structures on two complexes indicate that the pyrrole thioamide ligand is coordinated through the deprotonated pyrrole nitrogen, as well as the sulfur atom of the deprotonated thioamide group, forming five-membered chelate ring complexes. In both complexes, the two highest trans-influence donor atoms (C and S) are mutually cis. Related sets of platinum(II) and palladium(II) pyrrole thioamide complexes were similarly prepared by reactions of cis-[PtCl2(PPh3)2] and [PdCl2(dppe)] (dppe = Ph2PCH2CH2PPh2)] respectively. The complexes were characterised by NMR and IR spectroscopies, and ESI mass spectrometry. A preliminary investigation of the activity of a selection of compounds towards A549 (adenocarcinomic human alveolar basal epithelial) cells was also carried out.

Structural architectures and biological properties of main group bismuth(III) iodide complexes with heterocyclic thioamides

A series of mononuclear, dinuclear and polynuclear bismuth(III) iodide complexes (1–5) bearing heterocyclic thioamide ligands, 2-mercapto-3,4,5,6-tetrahydro-pyrimidine (tHPMT), 2-mercapto-benzimidazole (MBZIM), 2-mercapto-1-methylimidazole (MMI), 2-mercaptobenzothiazole (MBZT) and 2-mercaptopyridine (PYT), have been synthesized and characterized by melting point, elemental analysis, FT-IR spectroscopy, Raman spectroscopy, 1H, 13C NMR spectroscopy, UV–Vis spectroscopy and Thermal Gravimetry-Differential Thermal Analysis (TG-DTA). Moreover, the crystal structures of 1–5 have been also determined with single crystal X-ray diffraction analysis. The use of the above mentioned heterocyclic thioamide ligands have allowed synthesis of the first examples of bismuth(III) iodide thioamide complexes. {[BiI3(tHPMT)3]} (1) is the first structural example of a neutral mononuclear bismuth(III) iodide complex with octahedral geometry around the bismuth(III) ion with meridional conformation. {[BiI2(µ2-I)(MBZIM)2]2} (2) is the first example of a dinuclear bismuth(III) iodide complex with octahedral geometry around the bismuth(III) ion with trans-S/cis-I arrangement. {[BiI(µ2-I)2(MMI)]n} (3) and {[BiI(µ2-I)2(MBZT)]n·CH3OH} (4) are the first examples of the polynuclear bismuth(III) iodide complexes with octahedral geometry around the bismuth(III) ions. The ligand molecules are coordinated via the thione sulfur atoms in both complexes but in complex 3, ligand molecules are trans to each other in polymeric chain while, in complex 4, ligand molecules are cis to each other in polymeric chain. {[BiI(µ2-S,N-PYT)2]n} (5) is the first example of a polynuclear bismuth(III) iodide complex with pentagonal bipyramidal geometry around the bismuth(III) ions. The seven coordinate bismuth(III) atom has a N2S4I-donor set consisting of one iodine atom and two chelating and bridging μ2-S,N (η2-S:η1-N) pyridine-2-thionate anions.Complexes 1–5 were evaluated for their in vitro cytotoxic activity against human adenocarcinoma cervix (HeLa) and breast (MCF-7) cancer cells. The toxicity of the complexes was studied against human fetal lung fibroblast cells (MRC-5). The influence of 1–5, upon the catalytic peroxidation of the linoleic acid by the enzyme lipoxygenase (LOX), was evaluated experimentally.

Homoleptic and heteroleptic silver(I) complexes bearing diphosphane and thioamide ligands: Synthesis, structures, DNA interactions and antibacterial activity studies

Three silver(I) complexes bearing different combinations of diphosphanes and N-heterocyclic thioamides or thioamidates as ligands have been synthesized and structurally characterized: the ionic, homoleptic compound [Ag(xantphos)2][BF4] (1), where xantphos = 4,5-bis(diphenylphosphano)-9,9-dimethyl-xanthene, and the neutral, heteroleptic compounds [Ag(xantphos)(κ-S-pymt)] (2), where pymt = pyrimidine-2-thiolate, and [AgCl(dppbz)(κ-S-mtdztH)] (3), where dppbz = bis(diphenylphosphano)benzene and mtdztH = 5-methyl-1,3,4-thiadiazole-2-thione. X-ray crystallography studies reveal tetrahedral coordination environments around the silver(I) ions in compounds 1 and 3, while a trigonal planar arrangement of the P2S donor set has been found around the metal center in compound 2. The interaction of the three compounds with calf-thymus DNA was monitored by UV–vis spectroscopy, DNA-viscosity measurements and indirectly by testing their ability to compete with ethidium bromide for DNA intercalation sites studied by fluorescence emission spectroscopy. Intercalation was revealed as the most possible binding mode for the neutral compounds 2 and 3 and electrostatic interactions for the cationic complex [Ag(xantphos)2]+ in 1. Complexes 1–3 have also been found to display moderate in vitro antibacterial activity against the Gram-positive B. cereus, S. aureus and the Gram-negative E. coli bacterial strains, with the homoleptic bis-phosphane silver(I) compound 1 exhibiting a lower activity than the other two neutral compounds.

Bismuth(III) bromide-thioamide complexes: synthesis, characterization and cytotoxic properties

AbstractNew bismuth(III) bromine compounds of the heterocyclic thioamides were prepared and structurally characterized. The reaction of heterocyclic thioamides with bismuth(III) bromide resulted in the formation of the {[BiBr2(μ2-Br)(MMI)2]2·CH3COCH3·H2O} (1), {[BiBr2(MBZIM)4]·Br·2H2O} (2), {[BiBr2(μ2-Br)(tHPMT)2]2·CH3CN} (3), {[BiBr2(μ2-Br)(PYT)2]2·CH3CN} (4) and {[BiBr2(μ2-Br)(MBZT)2]22CH3OH} (5) complexes (MMI: 2-mercapto-1-methylimidazole, MBZIM: 2-mercaptobenzimidazole, tHPMT: 2-mercapto-3,4,5,6-tetrahydro-pyrimidine, PYT: 2-mercaptopyridine and MBZT: 2-mercaptobenzothiazole). The complexes1–5were characterized by melting point (m.p.), elemental analysis (e.a.), molar conductivity, Fourier-transform infrared (FT-IR), Fourier-transform Raman (FT-Raman), nuclear magnetic resonance (1H and13CNMR) spectroscopy, UV-Vis spectroscopy and thermogravimetric-differential thermal analysis (TG-DTA). The molecular structures of1–5were determined by single-crystal X-ray diffraction. Complex2is a first ionic monomuclear octahedral bismuth(III) bromide, while the complexes1,3–5are the first examples of dinuclear bismuth(III) bromide derivatives. Complexes1–5were evaluated in terms of theirin vitrocytotoxic activity against human adenocarcinoma breast (MCF-7) and cervix (HeLa) cells. The toxicity on normal human fetal lung fibroblast cells (MRC-5) was also evaluated. Moreover, the complexes1–5and free heterocyclic thioamide ligands were studied upon the catalytic peroxidation of the linoleic acid by the enzyme lipoxygenase (LOX).

Rare 3-D porous coordination networks based on N, S-mixed coordination showing selective detection of Fe3+ ion

Two rare 3-D porous coordination networks, {Ni(3-PPT)2]·H2O}n (1) and {[Zn(3-PPT)2]·3CH3OH·H2O}n (2), have been successfully constructed from a pyridine-substituted N-heterocyclic thioamide ligand, namely 3-PPT (3-PPT = 4-(3-pyridinyl)-pyrimidine-2-thiol). Complex 1 is composed of two identical coordination networks with dia topology interpenetrating into each other, and shows 1-D microporous channels along a axis. Complex 2 is assembled by 2-D square-grid layers stacked in an eclipsed fashion to give 1-D large square channels along b axis. Complexes 1 and 2 constitute two rare examples of 3-D porous coordination network based on N, S-mixed coordination. In particular, complex 1 exhibits the capability to selectively detect Fe3+ ion as a fluorescence “turn-off” sensor.

Syntheses, crystal structures and photophysical properties of d10 transition-metal (Ag+, Cu+, Cd2+ and Zn2+) coordination complexes based on a thiophene-containing heterocyclic thioamide

Four d10 transition-metal coordination complexes 1–4 (1: [Ag2(TPT)2(TPTH)2]; 2: [Cu6(TPT)6]·2DMF; 3: [Cd(TPT)2(TPTH)]·CH3CH2OH, 4: [Zn(TPT)2]n) have been constructed from a newly designed heterocyclic thioamide ligand, TPTH (TPTH = 4-(thiophen-2-yl)-pyrimidine-2-thiol). All complexes have been structurally elucidated by single crystal X-ray diffraction analyses. Except for 4, which shows a one-dimensional (1-D) chain structure, 1–3 are all discrete coordination complexes featuring dinuclear, hexanuclear and mononuclear entities, respectively. Their photophysical properties have been evaluated in the solid state at room temperature by UV–vis diffuse reflectance and luminescence spectra. Among them, 2 exhibits a strong red luminescence (λem = 699 nm) with a remarkable red-shift of the maximum emission compared to that of the TPTH ligand (λem = 536 nm). The red emission observed with 2 is ascribed to a LMCT (ligand-to-metal charge transfer) transition which agrees with the DFT calculations.

Femtosecond Study of Dimolybdenum Paddlewheel Compounds with Amide/Thioamide Ligands: Symmetry, Electronic Structure, and Charge Distribution in the 1MLCT S1 State.

Four photophysically interesting dimolybdenum paddlewheel compounds are synthesized and characterized: I and II contain amide ligand (N,3-diphenyl-2-propynamide), and III and IV contain thioamide ligand (N,3-diphenyl-2-propynethioamide). I and III are trans-Mo2L2(O2C-TiPB)2-type compounds, and II and IV are Mo2L4-type compounds, where O2C-TiPB is 2,4,6-triisopropylbenzoate. I-IV display strong light absorption due to metal to ligand charge transfer (MLCT) transitions from molybdenum to the amide/thioamide ligands. Charge transfer dynamics in the MLCT excited states of I-IV have been examined using femtosecond transient absorption (fs-TA) spectroscopy and femtosecond time-resolved infrared (fs-TRIR) spectroscopy. The asymmetric amide/thioamide ligands show two forms of regioarrangements in the paddlewheel compounds. Analyses of the ν(C≡C) bands in the fs-TRIR spectra of I and II show similar electron density distribution over ligands in their 1MLCT S1 states where only two amide ligands are involved and the transferred electron is mainly localized on one of them. The fs-TRIR spectra of III and IV, however, show different charge distribution patterns where the transferred electron is fully delocalized over two thioamide ligands in III and partially delocalized in IV. Fast interligand electron transfer (ILET) was recognized as the explanation for the various charge distribution patterns, and ILET was shown to be influenced by both the ligands and the ligand arrangements.

Versatile coordination ability of thioamide ligand in Ru(ii) complexes: synthesis, computational studies, in vitro anticancer activity and apoptosis induction

Two structurally different ruthenium(ii) complexesviadiverse coordination of thioamide ligand have been synthesised and characterized. The complexes exhibit significant cytotoxicity and induce apoptosis in cancer cells.

Efficient and recyclable Ru(II) arene thioamide catalysts for transfer hydrogenation of ketones: Influence of substituent on catalytic outcome

Six cationic ruthenium(II) arene thioamide complexes with the general molecular formula [Ru(η6-p-cymene)(PPh3)(L)]+ [where, L = pyridine-2-thioamide and its derivatives] have been successfully synthesized from the reaction of [Ru(η6-p-cymene)Cl2]2 with chelating thioamide ligands and PPh3 in methanol in 1:2 M ratio respectively. All the complexes were isolated as their BPh4−salts and were fully characterized by analytical and spectral (FT-IR, UV-Vis and1H-NMR) methods. The solid-state structure of one of the complexes, [Ru(η6-p-cymene)(PPh3)(L4)]BPh4 (4) (L4 = N-(2, 4, 6-Trimethylphenyl)pyridine-2-thiocarboxamide) has been established by X-ray single crystal diffraction which indicates a pseudo-octahedral (piano-stool) coordination geometry is present in the complex. The ruthenium(II) complexes have been examined for the transfer hydrogenation of various aromatic, heterocycle and cyclic ketones. The formation of ruthenium(II) hydride is confirmed by 1H- NMR and is proposed as the catalytic intermediate in this reaction. Under the optimized conditions, these ruthenium complexes served as excellent catalyst precursors which smoothly reduce the ketones with conversion up to 100%. The influence of other variables on the transfer hydrogenation reaction such as solvent, base, temperature, time, catalyst loading and substrate scope is also reported. Furthermore, the catalyst could be easily recovered and reused at least three times without obvious loss of conversions.