Ruthenium complexes containing group 5b donor ligands : Part VII. Rearrangement reactions of some ruthenium (II) complexes containing triphenylphosphine,tri-p-tolylphosphine or ethyldiphenylphosphine ligands.

As for [RuCl₂(PPh₃₃], carbonylation of [RuCl₂(PR₃)₃] [PR₃ = P(p-tolyl)₃, PEtPh₂) in N,N ¹-dimethylformamide (dmf) gives [Ru(CO)Cl₂ (dmf) (PR₃)₂] (II). For PR₃ = PEtPh₂, rearrangement of (II) in various solvents gives inseparable mixtures (³¹P evidence) but for PR₃ = P(p-tolyl)₃ [Ru₂(CO)₂Cl₄-{P(p-tolyl)₃}₃]is obtained. Reaction of [Ru(CO)Cl₂ (dmf) - {P(p-tolyl)₃}₂] with [RuCI₂{(P(p-tolyl)₃}₃] (1:1 mol ratio) gives [Ru₂ (CO) Cl₄ {P (p-tolyl)₃}₄] whereas reaction of [Ru (CO) Cl₂ (dmf) - (PPh₃₂] with (Rul₂ {P (p-tolyl)₃}₃] gives [Ru₂(CO)Cl₄ (PPh₃)₂] - {P(p-tolyl)₃}₂] - Reaction of [RuCl₂ {P(p-tolyl)₃}₃] with CS₂ gives the related [Ru₂Cl₄(CS) {P(p-tolyl)₃}₄] and [{RuCl₂(CS)}P(p-tolyl)₃{₂}₂] whereas [RuCl₂(PEtPh₂)₃] and CS₂ produce [RuCl₂(S₂CPEtPh₂) (PEtPh₂)₂]CS₂ and [Ru₂Cl₄(CS)₂(PEtph₂)₃].     

Ruthenium(II) complexes with triphenylphosphine or triphenylarsine and other monodentate ligands

Synthesis and studies on some five-coordinate ruthenium(II) complexes, viz. [Ru(MPh₃)(C₆H₅CHO)₂Cl₂] and [Ru(MPh₃)₂(CO)Cl₂] (where M = P or As) have been described. Reactions of [Ru(MPh3)(C₆H₅CHO)₂Cl₂] with N,N-dimethylformamide, dimethylsulphoxide and pyridine and of [Ru(MPh₃)₂(CO)Cl₂] with pyridine are described.     

Ruthenium(II) complexes containing bidentate Schiff bases and triphenylphosphine or triphenylarsine

Reactions of ruthenium(II) complexes [RuHX(CO)(EPh₃)₂(B)] (X = H or Cl; B = EPh₃, pyridine (py) or piperidine (pip); E = P or As) with bidentate Schiff base ligands derived by condensingo- hydroxyacetophenone with aniline,o- orp-methylaniline have been carried out. The products were characterized by analytical, IR, electronic and¹H-NMR spectral studies and are formulated as [Ru(X)(CO) (L)(EPh₃)(B)] (L = Schiff base anion; X = H or Cl; B = EPh₃, py or pip; E = P or As). An octahedral structure has been tentatively proposed for the new complexes. The new complexes were tested for their catalytic activities in the oxidation of benzyl alcohol to benzaldehyde.     

Ruthenium(III) complexes with tetradentate Schiff bases containing triphenylphosphine or triphenylarsine

Ruthenium(III) complexes of Schiff bases derived from the condensation of salicylaldehyde or o-vanillin with diamines have been prepared and characterised. The complexes are of the type [RuX(EPh₃)(L)] [X=Cl or Br; E=P or As; L=bis(salicylaldehyde)tetramethylenediimine, bis(salicylaldehyde)o-phenylenediimine, bis(o-vanillin)ethylenediimine, bis(o-vanillin)propylenediimine, bis(o-vanillin)tetramethylenediimine or bis(o-vanillin)o-phenylenediimine]. The Schiff bases behave as dibasic tetradentate ligands.     

Synthetic and catalytic investigations of ruthenium(III) complexes with triphenylphosphine/triphenylarsine and tridentate Schiff base

The synthesis and characterization of several hexa‐coordinated ruthenium(III) complexes of the type [RuCl(PPh₃)₂(L)] (L = dibasic tridentate ligand derived by the condensation of salicylaldehyde/o‐vanillin with o‐aminophenol/o‐aminothiophenol) are reported. IR, electronic, EPR spectral data and redox bahaviour of the complexes are discussed. An octahedral geometry has been tentatively proposed for all the complexes. The new complexes were found to be effective catalysts for the oxidation of benzyl alcohol and cyclohexanol to benzaldehyde and cyclohexanone respectively using N‐methylmorpholine‐N‐oxide as a co‐oxidant. Copyright © 2007 John Wiley & Sons, Ltd.     

Ruthenium(III) and ruthenium(II) complexes containing triphenylarsine and other ligands

The reactions of [RuCl₃(AsPh₃)₃] with ligands containing nitrogen (alkyl and aryl cyanides, pyridine, α-picoline N.N′-bipyridyl, 1,10-phenanthroline), oxygen (ketones, aldehydes, N,N-dimethylformamide, tetrahydrofuran, dimethylsulphoxide and nitroalkanes) and sulphur (CS₂ and Me₂S) donor atoms have been studied. The reactions of [RuCl₃(AsPh₃)₃] with tetra alkyl and aryl ammonium and arsonium salts have also been explored. The compounds obtained have been characterised by analyses, conductivity measurements, magnetic measurements and IR spectra. The electronic spectra of the complexes are discussed in terms of possible structures. An equilibrium between hexacoordinated and pentacoordinated species is suggested on the basis of electronic spectral studies.     

Mixed complexes of ruthenium(III) and ruthenium(II) with triphenylphosphine or triphenylarsine and other ligands

The reactions of [RuCl₃(AsPh₃)₃] with ligands containing nitrogen (ammonia, hydrazines, amine and thiocyanate) and oxygen (carboxylates) and the reactions of β-diketones (acetylacetone, dibenzoylmethane and benzoylacetone) with [RuCl₂(PPh₃)₂]_n and [RuCl₂(AsPh₃)₂]₂ have been studied. Apart from this, a new Ru(III) complex, [RuBr₃(AsPh₃)₃] has also been synthesized. The compounds obtained have been characterised by analyses, conductivity and magnetic measurements, molecular weight and spectral studies (IR and visible). An equilibrium between hexacoordinated and pentacoordinated species is suggested on the basis of electronic spectral studies.     

Electrochemical transformations of antimony(V) complexes containing tridentate O,N,O-donor ligands

Electrochemical transformations of antimony(V) complexes containing a tridentate redoxactive ligand, N,N-bis-(2-hydroxy-di-3,5-tert-butylphenyl)amine: R ₃Sb(Cat-NH-Cat) (R = (1) Ph; (2) Et), (3) Et₂Sb(Cat-N-Cat)) are studied. Electrochemical oxidation of complexes 1, 2 occurs irreversibly leading to formation of unstable radical cations. The next stage is the chemical process resulting in formation of neutral paramagnetic compounds. The Et₂Sb(V)(Cat-N-Cat) complex is characterized by two reversible anodic redox processes corresponding to a change of in the ligand redox level. Stable paramagnetic derivatives are formed as a result of electrochemical oxidation of compounds 1, 3; this allows considering these compounds as potential radical scavengers. Interaction of complex 1 with electrogenerated superoxide radical anion led to formation of paramagnetic reaction products.     

Charge-transfer luminescence from ruthenium(II) complexes containing tridentate ligands

Four complexes of the general formula Ru(NNN)²⁺₂ (N NN = tridentate N-heterocyclic ligand) were synthesized and studied spectroscopically. All exhibit visible absorption spectra that are charge-transfer-to-ligand in origin, are luminescent in glasses at 77 K, and display emission spectra that possess energies, structures, and decay tines that label them as charge transfer.     

Syntheses and oxidation of methyloxorhenium(V) complexes with tridentate ligands

Four new methyloxorhenium(V) compounds were synthesized with these tridentate chelating ligands: 2-mercaptoethyl sulfide (abbreviated HSSSH), 2-mercaptoethyl ether (HSOSH), thioldiglycolic acid (HOSOH), and 2-(salicylideneamino)benzoic acid (HONOH). Their reactions with MeReO(3) under suitable conditions led to these products: MeReO(SSS), 1, MeReO(SOS), 2, MeReO(OSO)(PAr(3)), 3, and MeReO(ONO)(PPh(3)), 4. These compounds were characterized spectroscopically and crystallographically. Compounds 1 and 2 have a five-coordinate distorted square pyramidal geometry about rhenium, whereas 3 and 4 are six-coordinate compounds with distorted octahedral structures. The kinetics of oxidation of 2 and 3 in chloroform with pyridine N-oxides follow different patterns. The oxidation of 2 shows first-order dependences on the concentrations of 2 and the ring-substituted pyridine N-oxide. The Hammett analysis of the rate constants gives a remarkably large and negative reaction constant, rho = -4.6. The rate of oxidation of 3 does not depend on the concentration or the identity of the pyridine N-oxide, but it is directly proportional to the concentration of water, both an accidental and then a deliberate cosolvent. The mechanistic differences have been interpreted as reflecting the different steric demands of five- and six-coordinate rhenium compounds.     

Mixed-ligand oxovanadium(V) complexes incorporating bidentate salicylaldehyde and tridentate aldimine ligands

Summary Mixed-ligand oxovanadium(V) complexes, [V^VO(L)-(sal)], containing salicylaldimine ligands of -amino acids H₂L [(1);R = Me, i-Pr and CH₂Ph] and salicylaldehyde (Hsal) have been synthesized. The coordination sphere of the complexes is of the VO(ONO)(OO) type, where O atoms are phenolic, carboxylic and aldehydic, and N is of the azomethine type. The complexes are diamagnetic and exhibit only one LMCT band at ca. 490 nm. They display quasi-reversible one-electron reduction peaks in a CH₂Cl₂-MeCN (21v/v) mixture in the 0.07–0.13V versus s.c.e. range. A trend in the redox potential data has been rationalized on the basis of conventional normal substituent effects.     

Carbonyl cationic rhodium(I) and iridium(I) complexes with sulphur donor and triphenylphosphine ligands

Summary The reaction of previously reported Rh^I and Ir^I cationic complexes towards carbon monoxide and triphenylphosphine has been studied. Carbonyl rhodium(I) mixed complexes of the formulae [Rh(CO)L₂(PPh₃)]ClO₄, (L=tetrahydrothiophene(tht), trimethylene sulfide(tms), SMe₂, or SEt₂), [(CO)(PPh₃)Rh{-(L-L)}₂Rh(PPh₃)(CO)](ClO₄)₂ (L-L= 2,2,7,7-tetramethyl-3,6-dithiaoctane (tmdto), (MeS)₂(CH₂)₃ (dth), or 1,4-dithiacyclohexane (dt), [Rh(CO)L(PPh₃)₂]ClO₄ (L= tht, tms, SMe₂, or SEt₂), and carbonyl iridium(I) complexes of the formulae [Ir(CO)₂(COD)(PPh₃)]ClO₄, [Ir(CO)(COD)(PPh₃)₂]ClO₄, [(CO)(COD)(PPh₃) Ir{-(L-L)} Ir(PPh₃)(COD)(CO)](ClO₄)₂ (L-L = tmdto or dt), [(CO)₂ (PPh₃)Ir(-tmdto)Ir(PPh₃)(CO)₂](ClO₄)₂, [(CO)₂(PPh₃) Ir(-dt)₂Ir(PPh₃)(CO)₂](ClO₄)₂, were prepared by different synthetic methods.     

Synthesis,characterization, crystal structure,and reactivity of heterobimetallic dioxovanadium(V) complexes containing multidentate hydrazone ligands

Two new heterobimetallic complexes of the composition [(VO₂)₂(μ₃-slsch){Na₂(μ-H₂O)₂(H₂O)₂}]_n (1) and [(VO₂)₂(μ₃-npsch){Na₂(μ-H₂O)₂(H₂O)₂}(DMF)]_n (2) were obtained by reaction of the ligand and vanadium pentoxide in a 1:1 molar ratio in methanol in the presence of Na₂CO₃ (2 equivalents). The complexes obtained were characterized using various spectroscopic studies. The structures of both the complexes were established by single crystal X-ray crystallographic study. We have also explored the catalytic behavior of the complexes in oxidative bromination of phenol red, which is the bio-inspired reaction catalyzed by an enzyme haloperoxidase.     

Synthesis and characterization of cyclometalated iridium(III) complexes containing pyrimidine-based ligands

New pyrimidine derivatives (pyr) have been synthesized using palladium-catalyzed Suzuki coupling reaction. These compounds can undergo cyclometalation with iridium trichloride to form bis-cyclometalated iridium complexes, (pyr)₂Ir(acac) (acac = acetylacetonate; pyr = cyclometalated pyr). The substituents at the both cyclometalated phenyl ring and pyrimidine ring were found to affect both electrochemical and photophysical properties of the complexes. Computation results on these complexes are consistent with the electrochemical and photophysical data. The complexes are green-emitting with good solution quantum yields at ∼0.30. Light-emitting devices using these complexes as dopants were fabricated, and the device performance at 100 mA/cm² are moderate: 9 (17 481 cd/m², 4.8%, 18 cd/A, 5.1 lm/W); 10 (18 704 cd/m², 4.9%, 18.9 cd/A, 4.7 lm/W); 13 (20 942 cd/m², 5.4%, 21.0 cd/A, 6.1 lm/W).     

Synthesis, spectroscopic characterization, redox properties and catalytic activity of some ruthenium(II) complexes containing aromatic aldehyde and triphenylphosphine or triphenylarsine

A series of new mixed ligand penta-coordinated square pyramidal ruthenium(II) complexes containing benzaldehyde or its substituents and triphenylphosphine or triphenylarsine have been synthesized and characterized. In the electronic spectra, three well-defined peaks in the visible region were observed and assigned to d-d transitions in D(4h) and low spin axially distortion from O(h) symmetry. The spectrochemical parameters of the complexes were calculated and placed the ligands in the middle of the spectrochemical series. The redox properties and stability of the complexes toward oxidation were related to the electron-withdrawing or releasing ability of the substituent in the phenyl ring of the benzaldehyde. The electron-withdrawing substituents stabilized Ru(2+) complexes, while electron-donating groups favored oxidation to Ru(3+). The mechanism and kinetics of the catalytic oxidation of benzyl alcohol by the complex [RuCl(2)(Pph(3))(C(6)H(5)CHO)(2)] in the presence of N-methylmorpholine-N-oxide have also been studied.     

Photophysical and electrochemical properties of Ru(II) complexes containing tridentate bisphosphino-oligothiophene ligands

Nine Ru(II) complexes containing the conjugated oligothiophene ligands 3,3'-bis(diphenylphosphino)-2,2':5',2'-terthiophene (P(2)T(3)) and 4',3'-bis(diphenylphosphino)-3,3'-dihexyl- 2,2':5',2':5',2':5',2'-pentathiophene (P(2)T(5)) were prepared and characterized. P(2)T(3) and P(2)T(5) bond as tridentate ligands and three of the complexes (1, 2 and 5) form green five-coordinate Ru(II) complexes in solution. Cyclic voltammetry, variable temperature UV-vis spectroscopy and time-resolved transient absorption spectroscopy were used to characterize the electronic properties of the complexes. Increased conjugation in the complexes containing the P(2)T(5) ligand resulted in a lowering of the oxidation potential of the oligothiophene, but electropolymerization was not observed. The electronic spectra were dominated by π-π* transitions. All of the complexes were non-emissive both at room temperature and low temperature, indicating the excited state decays by other, non-radiative pathways. The transient absorption spectrum of complex 7 shows a species with a band at 475 nm and a lifetime of ～100 ns, assigned to a ligand-based triplet state.     

Ru(III) complexes containing 3,5-pyrazole dicarboxylic acid and triphenylphosphine/triphenylarsine: Synthesis, characterization and catalytic activity

New hexa-coordinated Ru(III) complexes of the type [Ru(H₂Pzdc)(EPh₃)₃X₂] have been synthesized by reacting 3,5-pyrazole dicarboxylic acid (H₃Pzdc) with the appropriate starting complexes [RuX₃(EPh₃)₃] (where X = Cl or Br; E = P or As). The ligand behaves as a bidentate monobasic chelate. All the complexes have been characterized by analytical and spectroscopic (IR, electronic and EPR) data. Single-crystal X-ray analysis of the complex [Ru(H₂Pzdc)(PPh₃)₂Cl₂]·C₆H₆·C₂H₅OH revealed that the coordination environment around the ruthenium center consists of an NOP₂Cl₂ octahedron. The planar ligand occupies the equatorial position along with two chlorine atoms, while the triphenylphosphine groups occupy the axial positions. The electrochemical behavior of the new complexes was studied using cyclic voltammetry. The new mononuclear ruthenium complexes are capable of acting as catalysts for the oxidation of alcohols.     

fac-Re(CO)3L complexes containing tridentate monoanionic ligands (L-) with a seldom-studied sulfonamido group as one terminal ligating group

To achieve a net-neutral coordination unit in radiopharmaceuticals with a fac-M(CO)3+ core (M = Tc, Re), facially coordinated monoanionic tridentate ligands are needed. New neutral fac-Re(CO)3L complexes were obtained by treating fac-[Re(CO)3(H2O)3]+ with unsymmetrical tridentate NNN donor ligands (LH) based primarily on a diethylenetriamine (dien) moiety with an aromatic group linked to a terminal nitrogen through a sulfonamide. LHs contain 2,4,6-trimethylbenzenesulfonyl (tmbSO2) and 5-(dimethylamino)naphthalene-1-sulfonyl (DNS) groups. X-ray crystallographic and NMR analyses confirm that in both the solid and the solution states all L- in fac-Re(CO)3L complexes are bound in a tridentate fashion with one donor being nitrogen from a deprotonated sulfonamido group. Another fundamental property that is important in radiopharmaceuticals is shape, which in turn depends on ring pucker. For L- = tmbSO2-dien-, tmbSO2-N'-Medien-, and tmbSO2-N,N-Me2dien-, the two chelate rings have a different pucker chirality, as is commonly found for a broad range of metal complexes. However, for fac-Re(CO)3(DNS-dien), both chelate rings have the same pucker chirality because the sulfonamido ring has an unusual pucker for the absolute configuration at Re; a finding that is attributable to intramolecular and intermolecular hydrogen bonds from the sulfonamido oxygens to the NH2 groups. Averaging of tmb NMR signals, even at -90 degrees C for Re(CO)3(tmbSO2-N,N-Me2dien), indicates rapid dynamic motion in the complexes with this group. However, examination of the structures suggests that free rotation about the S-C(tmb) bond is not possible but that concerted coupled rotations about the N-S and the S-C bonds can explain the NMR data.     

Reactions of some electrophilic olefins with (carbonato)bis(triphenylphosphine)- and (carbonato)bis(triphenylarsine)-platinum complexes

Carbonato complexes L₂PtCO₃ (L = PPh₃ or AsPh₃) react with certain electrophilic olegins, such as 1,1-dicyanoolefins, under mild conditions to liberate CO₂. The reaction of L₂PtCO₃ with tetracyanoethylene at room temperature is solvent dependent, and in alcoholic solvents, in contrast to an earlier report, the dicyano complexes, L₂Pt(CN)₂, and tricyanoethenolato complexes, L₂Pt(CN) [OC(CN)C(CN)₂] have been isolated and identified.     

Preparation and electroluminescent application of iridium(III) complexes containing sulfur-containing phenylpyridazine ligands

Transition Metal Chemistry - Four iridium(III) complexes (1–4) with sulfur-containing phenylpyridazine ligands were successfully synthesized and characterized. The structure of complex 3 was...