Some benzimidazole amide complexes of ruthenium(II)

The synthesis and characterisation of ruthenium(II) complexes with 2-amidobenzimidazoles are reported. The complexes RuCl₂(DMSO)₄ and RuCl₂(PPh₃) react with 2-(acetamido)benzimidazole (AB) and 2-(benzamido)benzimidazole (BB) it acetone to give products of the type [Ru(L)₂(N−O)₂]Cl₂ [L=DMSO, PPh₃, N−O=AB, BB). The displacement reactions are faster in the case of methyl (AB) than phenyl (BB) substituted ligands. The ligands are bifunctional chelating agents coordinating through the tertiary nitrogen of benzimidazole ring and amide oxygen. The complexes are characterised based on their elemental analysis, conductivity data, infrared,¹H and³¹P nmr spectra. Acis-geometry is proposed for all the complexes reported.     

Synthesis of 2‐aminomethylpiperidine ruthenium(II) phosphine complexes and their applications in transfer hydrogenation of aryl ketones

The complex trans,cis‐[RuCl₂(PPh₃)₂(ampi)] (2) was prepared by reaction of RuCl₂(PPh₃)₃ with 2‐aminomethylpiperidine(ampi) (1). [RuCl₂(PPh₂(CH₂)_nPPh₂)(ampi) (n = 3, 4, 5)] (3–5) were synthesized by displacement of two PPh₃ with chelating phosphine ligands. All complexes (2–5) were characterized by ¹ H, ¹³C, ³¹P NMR, IR and UV‐visible spectroscopy and elemental analysis. They were found to be efficient catalysts for transfer hydrogen reactions. Copyright © 2012 John Wiley & Sons, Ltd.     

Binuclear ruthenium(III) complexes: synthesis,characterisation, catalytic activity in aryl–aryl couplings and biological activity

Binuclear ruthenium(III) complexes containing a binucleating Schiff base ligand, L and Ph₃P or Ph₃As, [RuX₂(EPh₃)₂]₂L (X = Cl or Br; E = P or As) have been prepared by reacting [RuCl₃(PPh₃)₃], [RuCl₃(AsPh₃)₃], [RuBr₃(AsPh₃)₃] and [RuBr₃(PPh₃)₂(MeOH)] with Schiff bases in a 2:1 molar ratio. The Schiff bases used in this study were prepared by condensing the appropriate diamine with salicylaldehyde or benzoylacetone in a 1:2 molar ratio respectively. The complexes were characterised by analytical, spectral (i.r., electronic, e.p.r.) and electrochemical data. An octahedral structure has been proposed for all the new ligand-bridged binuclear Ru^III complexes. The new complexes have been used as catalysts in aryl–aryl couplings and also subjected to antifungal activity studies.     

Platinum group metal functionalized phosphine complexes. Part 2. Phosphinoamide rhodium(I), iridium(I), palladium(II) and platinum(II) complexes

Summary Rhodium(I), iridium(I), palladium(II) and platinum(II) complexes of the phosphinoamide ligands, Ph₂PCH₂CONHR (R = H, HDPA; Me, MDPA; Ph, PDPA) were prepared and characterized by using conductivity data, i.r., ¹H and ³¹P(H) n.m.r. spectral data. Reaction of the ligands with MCl(PPh₃)₃ and MCl(CO)(PPh₃)₂ (M = Rh, Ir) in CH₂Cl₂ under reflux lead to the formation of MCl(PPh₃)₂ [Ph₂PCH₂C(O)NHR] and MCl(CO)(PPh₃)[Ph₂PCH₂–C(O)HNR] respectively. The reaction of either K₂MCl₄ or cis-MCl₂(PPh₃)₂ affords complexes of the type cis-MCl₂[Ph₂PCH₂C(O)NHR]₂ (M = Pd, Pt). A similar product results even from the reaction of phosphinoamides with cis-platin. Possible structures are proposed for the complexes based on their physicochemical data     

Preparation,spectral characterization,electrochemistry, EXAFS,antibacterial and catalytic activity of new ruthenium (III) complexes containing ONS donor ligands with triphenylphosphine/arsine

New hexa‐coordinated ruthenium (III) complexes of the type [RuX(EPh₃)₂(L)] (X = Cl or Br; L = dibasic tridentate Schiff base ligand; E = P or As) have been synthesized by the reactions of [RuCl₃(PPh₃)₃], [RuCl₃(AsPh₃)₃] or [RuBr₃(AsPh₃)₃] with the appropriate Schiff base ligands derived by the condensation of salicylaldehyde and 2‐hydroxy‐1‐naphthaldehyde with N(4) substituted thiosemicarbazones. All the new complexes were characterized using various physico‐chemical methods such as elemental analyses, infrared, electron paramagnetic resonance (EPR) spectroscopy, magnetic moment and cyclic voltammetry. Based on the extended X‐ray absorption fine structure (EXAFS) analysis, an octahedral structure has been confirmed for the complexes. The new complexes have been subjected to the catalytic activity and antibacterial studies. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis,crystal, molecular and electronic structures of thiocyanate ruthenium(II) complexes with pyrazole,benzimidazole and triazole ligands

The [Ru(SCN)₂(PPh₃)₂(L)₂] complexes, where L = HPz, PhIm, HTz, have been prepared and studied by IR, NMR, UV–vis spectroscopy and X-ray crystallography. The complexes were prepared in the reactions of [RuCl₂(PPh₃)₃] with pyrazole, benzimidazole and triazole in methanol solutions. The electronic structures of the obtained compounds have been calculated using the TD–DFT method.     

Spectrometric,catalytic, and antimicrobial studies of mononuclear Ru(III) Schiff-base complexes

A series of air stable low spin Ru(III) complexes, [RuX₂(EPh₃)(L)] (where X = Cl or Br; E = P or As; L = monobasic tridentate Schiff-base ligand), have been synthesized by reacting [RuCl₃(PPh₃)₃], [RuCl₃(AsPh₃)₃], and [RuBr₃(PPh₃)₃] with the Schiff base in 1 : 1 molar ratio in benzene. These complexes have been characterized by elemental analysis, FT-IR, UV-Vis, and EPR spectroscopy together with magnetic susceptibility. The redox behaviors of the complexes have been investigated by cyclic voltammetric technique. Catalytic efficiency of the ruthenium complexes was determined for aryl–aryl coupling and the oxidation of primary and secondary alcohols into their corresponding aldehydes and ketones in the presence of molecular oxygen as co-oxidant. All complexes were screened for antibacterial activity.     

New routes to carbonyl complexes of general formula [RuCl2(CO)(S)(PPh3)2] (S = DMA,DMF, DMSO): crystal structure of [RuCl2(CO)(DMA)(PPh3)2] · 1/2CH2Cl2

The compound [RuCl₂(CO)(DMA)(PPh₃)₂] [DMA = dimethylacetamide] was obtained from [RuCl₃(PPh₃)₂-(DMA)] · DMA and CO in DMA. Orange crystals of [RuCl₂(CO)(DMA)(PPh₃)₂] · 1/2CH₂Cl₂ were isolated by slow evaporation of a CH₂Cl₂/DMA solution and its structure was determined by single crystal X-ray diffraction. The analogous compounds containing DMF and DMSO were obtained from the precursor ttt-[RuCl₂(CO)₂(PPh₃)₂]. Characterization of the other complexes is based on i.r. and n.m.r. spectroscopy, including ³¹P{¹H} data.     

Novel bidentate ruthenium(III) Schiff base complexes: synthetic,spectral, electrochemical,catalytic and antimicrobial studies

Ru^III complexes of the type [RuX(L)₂(E)] (X = Cl or Br; L = novel bidentate Schiff base ligand; E = PPh₃ or AsPh₃) have been prepared by reacting [RuX₃(E)₃] or [RuBr₃(PPh₃)₂(MeOH)] with two novel bidentate Schiff base ligands derived from 4-(1-methyl-1-mesitylcyclobutane-3-yl)-2-aminothiazole, in a 1:2 molar ratio in benzene, and characterised by analytical, spectral (i.r., electronic, ¹H-, ¹³C- n.m.r., and e.p.r.) and electrochemical data. An octahedral structure has been tentatively proposed for all the new complexes. The thermal properties of the ligands and their complexes have been studied by t.g.a. The new Ru^III complexes are effective catalysts for the oxidation of alcohols to carbonyl compounds but are unable to oxidise alkenes in the presence of N-methylmorpholine-N-oxide (NMO) as co-oxidant. The antimicrobial activity of the ligands and complexes have also been tested against six microorganisms.     

Synthesis,crystal, molecular and electronic structures of thiocyanate ruthenium complexes with pyridine and its derivatives as ligands

The complexes [Ru(SCN)₂(PPh₃)₂(L)₂], where L = py and γ-pic, and [Ru(SCN)₂(PPh₃)₂(L)], where L = py-2-CH₂NH₂ and py-2-CH₂O, have been prepared and studied by IR, NMR, EPR, UV–Vis spectroscopy and X-ray crystallography. The complexes were prepared in the reactions of [RuCl₂(PPh₃)₃] with pyridine, γ-picoline, 2-(aminomethyl)pyridine and 2-(hydroxymethyl)pyridine in methanol solutions. The electronic structures of the obtained compounds have been calculated using the DFT/TD-DFT method.     

Ruthenium(II) complexes with 2-methyl-3-substituted (3H)-quinazolin-4-ones

A number of ruthenium(II) complexes of some polydentate ON, OO and ONO donors in the form of 2-methyl-3-substituted (3H)-quinazolin-4-ones have been synthesized and studied. The reaction between RuCl₂(DMSO)₄ and the uninegative bidentate ligands yielded complexes of the type Ru(DMSO)₂(OO)₂ (OO = MHQ, PHQ, MHEQ, MHPQ or MCMQ), displacing only two DMSO groups along with chlorides, whereas the neutral bidentate ligands gave RuCl₂(ON)₂ (ON = MAQ, PAQ, MANQ, PANQ, MAAQ, MAPQ, MPQ or PPQ), displacing all the DMSO groups. A uninegative terdentate ligand (MHAQ) with ONO donors, however, yielded a bis chelate of ruthenium(II).     

Facile synthesis of [(NHC)(NHCewg)RuCl2(CHPh)] complexes

The utility of [(NHC)(PPh₃)RuCl₂(CHPh)] for the facile and efficient synthesis of ten complexes of the type [(NHC)(NHC_ewg)RuCl₂(CHR)] with saturated and unsaturated NHC ligands in 85-94% isolated yield via a simple one step synthesis utilizing [AgI(NHC_ewg)] as NHC_ewg transfer reagents was demonstrated.     

Synthesis and structures of two ruthenium dibenzoylmethane triphenylphosphine mixed ligand complexes

The reaction of dibenzoylmethane (HDBM) with [RuCl₂(PPh₃)₃] in benzene in the presence of a supporting base (Et₃N) under reflux gives two different complexes, the side product as a green-yellow Ru(III) compound of composition [Ru^IIICl₂(DBM)(PPh₃)₂] (2) and the main product as a red Ru(II) complex of composition [Ru^II(DBM)₂(PPh₃)₂] (3). The products were studied by spectroscopic methods, cyclic voltammetry and X-ray single crystal diffraction. The molecular structure of 2 shows a distorted octahedral environment around the Ru atom with two phosphine ligands in trans positions. The octahedral complex 3 shows a cis arrangement of two phosphine ligands.     

Synthesis,spectral characterization and catalytic applications of Ru(II) complexes with amide ligands

Ruthenium(II) complexes of the type, RuCl₂(NO)(PPh₃)(L₂) (where L = amide ligand) have been synthesized and characterized on the basis of their elemental analysis IR, ¹H-, ¹³C-, ³¹P-NMR spectra. Amide ligand behaved as a bidentate ligand. The probable structures of these complexes have been discussed. They were used as catalysts for the hydrolysis of drugs viz. rivastigmine tartrate and neostigmine bromide. The percent yields of hydrolyzed products of these drugs were determined spectrophotometrically.     

Schiff base complexes of ruthenium(II) with tridentateN-methyl-S-methyldithiocarbazate ligands

Summary Schiff bases (HL) produced by the condensation ofN-methyl-S-methyldithiocarbazate with -diketones and aromatic aldehydes or ketones react with [RuHClCO(PPh₃)₃] to yield hexacoordinated complexes of the type [RuClCO(PPh₃)₂(L)]. These Schiff bases react with [RuCl₂{P(OR)₃}₄] in 11 molar ratio to yield [RuCl{P(OR)₃}₂(L)] in which L is a tridentate. The chlorine atom in the complex can be removed in coordinating solvents in the presence of anions such as [BPh₄]^– to give cationic complexes. Bis chelate complexes, [Ru{P(OR)₃}₂(L)₂] are prepared from 12 molar proportions of the reactants. These complexes were characterised by elemental analyses, i.r.,¹H n.m.r., u.v. and conductivity studies.NCL Communication No. 4224.     

Synthesis and metathesis activity of ruthenium dimethylvinyl carbene complexes

Two new dimethylvinyl carbene complexes, RuCl₂(SIMes)(PPh₃)CHCHC(CH₃)₂ and RuCl₂(SIMes)(3BP)₂CHCHC(CH₃)₂, were synthesized from RuCl₂(PCp₃)₂CHCHC(CH₃)₂. Complex RuCl₂(SIMes)(3BP)₂CHCHC(CH₃)₂ does not suffer from the problem of incomplete initiation that has been observed for the other dimethylvinyl carbene complexes, as witnessed by complete and rapid reaction with ethyl vinyl ether. Acyclic diene metathesis (ADMET) polymerization of 1,9‐decadiene with these complexes was found to give polymers with chemical and thermal properties similar to those obtained with Schrock's molybdenum catalyst. These complexes are also catalysts for ring‐opening metathesis polymerization. The parent complex RuCl₂(SIMes)(PCp₃)CHCHC(CH₃)₂ was found to give polyoctenamer with high initial heats of fusion, suggesting a dependence of the “as formed” crystallinity of the polymer on the rate of the ROMP reaction. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6134–6145, 2005     

Reactions of [(Cp)2Ti(NCS)2] as a potential metalloligand; synthesis and physico-chemical investigations of novel heterobimetallic complexes

Summary Bis(cyclopentadienyl)titanium(IV) diisothiocyanate [(Cp)₂-Ti(NCS)₂] reacts with MCl₂ (M = Cu, Pd or Pt), [CuCl(PPh₃)₃], [RuCl₂(PPh₃)₃] and [RuCl₂(DMSO)₄] (DMSO = dimethylsulphoxide) giving solid compounds of stochiometry [(Cp)₂Ti(-NCS)₂MCl₂] (M = Cu, Pd or Pt), [(Cp)₂Ti(-NCS)₂CuCl(PPh₃)], [(Cp)₂Ti(-NCS)₂-RuCl(PPh₃)₂]Cl and [(Cp)₂Ti(-NCS)₂RuCl₂(DMSO)2]. These products have been characterized by physicochemical and spectroscopic methods.     

Ruthenium(II) complexes with ferrocene-modified arene ligands: synthesis and electrochemistry

A series of arene-ruthenium complexes of the general formula [RuCl₂{η⁶-C₆H₅(CH₂)₂R}L] with R=OH, CH₂OH, OC(O)Fc, CH₂OC(O)Fc (Fc=ferrocenyl) and L=PPh₃, (diphenylphosphino)ferrocene, or bridging 1,1^′-bis(diphenylphosphino)ferrocene, have been synthesized. Two synthetic pathways have been used for these ferrocene-modified arene-ruthenium complexes: (a) esterification of ferrocene carboxylic acid with 2-(cyclohexa-1,4-dienyl)ethanol, followed by condensation with RuCl₃ · nH₂O to afford [RuCl₂{η⁶-C₆H₅(CH₂)₂OC(O)Fc}]₂, and (b) esterification between ferrocene carboxylic acid and [RuCl₂{η⁶-C₆H₅(CH₂)₃OH}L] to give [RuCl₂{η⁶-C₆H₅(CH₂)₃OC(O)Fc}L]. All new compounds have been characterized by NMR and IR spectroscopy as well as by mass spectrometry. The single-crystal X-ray structure analysis of [RuCl₂{η⁶-C₆H₅(CH₂)₃OH}(PPh₃)] shows that the presence of a CH₂CH₂CH₂OH side-arm allows [RuCl₂{η⁶-C₆H₅(CH₂)₃OH}(PPh₃)] to form an intramolecular hydrogen bond with a chlorine atom. The electrochemical behavior of selected representative compounds has been studied. Complexes with ferrocenylated side arms display the expected cyclic voltammograms, two independent reversible one-electron waves of the Ru(II)/Ru(III) and Fe(II)/Fe(III) redox couples. Introduction of a ferrocenylphosphine onto the ruthenium is reflected by an additonal reversible, one-electron wave due to ferrocene/ferrocenium system which is, however, coupled with the Ru(II)/Ru(III) redox system.     

Pentane-2,4-dione complexes of technetium99

Summary Pentane-2,4-dionatotechnetium⁹⁹ complexes of the type PPh₄[TcX₄(acac)], TcBr₃(acac)PPh3, TcX₂(acac)₂, TcX₂ (acac) (PPh₃)₂, TcX(acac)₂ PPh₃ and Tc(acac)₃ (X=Cl or Br) have been prepared and characterized. Where possible, their configurations have been determined from elemental analyses, conductivity and magnetic susceptibility measurements, and by i.r. and u.v.-visible spectroscopy.     

Selective hydrogenations of steroids catalyzed by heterogenized Ru complexes

Summary [RuCl₂(PPh₃)₃], [{RuCl₂(TPPMS)₂}₂] and their heterogenized analogs were applied in the selective hydrogenation of 17-keto- and α,β-unsaturated ketosteroids. In basic conditions these complexes selectively hydrogenated the C=O bonds, similarly to the results obtained in the case of α,β-unsaturated aldehydes. A new method was developed for the synthesis of an expensive steroid alcohol, which can be prepared traditionally in a more complicated way.