Ruthenium titanocene and ruthenium titanium half-sandwich bimetallic complexes in catalytic cyclopropanation

The reaction of the phosphine functionalised titanium half-sandwich complexes 7, 9 and 10 with the binuclear complex [(p-cymene)RuCl₂]₂ allowed the access to three new early-late bimetallic complexes (p-cymene)[(μ-η⁵:η¹-C₅H₄(CH₂)_nPR₂)TiX₃]RuCl₂ (11-13). The structure of 11 (n = 0, X = Cl) has been confirmed by X-ray diffraction. The ruthenium titanium half-sandwich bimetallic complexes so formed and the ruthenium titanocene analogues 4-6 catalyse the addition of ethyl diazoacetate to styrene with high selectivity toward cyclopropanation versus metathesis contrary to the monometallic complexes (p-cymene)RuCl₂PR₃.     

Synthesis and spectral studies on heterobimetallic complexes of manganese and ruthenium derived from bis[N-(2-hydroxynaphthalen-1-yl)methylene]oxaloyldihydrazide

The complex [Mn(L)(H₂O)₂] [H₄L = bis[N-(2-hydroxynaphthalen-1-yl)methylene]-oxaloyldihydrazide] reacts with activated ruthenium(III) chloride in methanol in 1:1.2 M ratio under reflux resulting in heterobimetallic complex of the composition [Mn(L)(H₂O)₄RuCl₂]Cl. The complexes of the composition [Mn(L)(A)₄RuCl₂]Cl were obtained when the above reaction was carried out in presence of heterocyclic nitrogen bases(A) such as pyridine(py), 3-picoline(3-pic) and 4-picoline(4-pic). The molar conductance values for these complexes in DMF(N,N-dimethyl formamide) solution indicate their 1:1 electrolytic nature. Magnetic moment values suggest that these heterobimetallic complexes contain Mn(IV) and Ru(III) in the same structural unit. Electronic spectral studies suggest six coordinated metal ions in these complexes. IR spectra reveal that the H₄L ligand coordinates in its keto-form to Mn(IV) and Ru(III).     

Bimetallic ruthenium-tin chemistry: Synthesis and molecular structure of arene ruthenium complexes containing trichlorostannyl ligands

A series of neutral, anionic and cationic arene ruthenium complexes containing the trichlorostannyl ligand have been synthesised from SnCl₂ and the corresponding arene ruthenium dichloride dimers [(η⁶-arene)Ru(μ₂-Cl)Cl]₂ (arene = C₆H₆, PrⁱC₆H₄Me). While the reaction with triphenylphosphine and stannous chloride only gives the neutral mono(trichlorostannyl) complexes [(η⁶-C₆H₆)Ru(PPh₃)(SnCl₃)Cl] (1) and [(η⁶-PrⁱC₆H₄Me)Ru(PPh₃)(SnCl₃)Cl] (2), the neutral di(trichlorostannyl) complex [(η⁶-PrⁱC₆H₄Me)Ru(NCPh)(SnCl₃)₂] (3) could be obtained for the para-cymene derivative with benzonitrile as additional ligand. By contrast, the analogous reaction with the benzene derivative leads to a salt composed of the cationic mono(trichlorostannyl) complex [(η⁶-C₆H₆)Ru(NCPh)₂(SnCl₃)]⁺ (5) and of the anionic tris(trichlorostannyl) complex [(η⁶-C₆H₆)Ru(SnCl₃)₃]⁻ (6). On the other hand, [(η⁶-PrⁱC₆H₄Me)Ru(μ₂-Cl)Cl]₂ reacts with SnCl₂ and hexamethylenetetramine hydrochloride or 18-crown-6 to give the anionic di(trichlorostannyl) complex [(η⁶-PrⁱC₆H₄Me)Ru(SnCl₃)₂Cl]⁻ (4), isolated as the hexamethylenetetrammonium salt or the chloro-tin 18-crown-6 salt. The single-crystal X-ray structure analyses of 1, 2, [(CH₂)₆N₄H][4], [(18-crown-6)SnCl][4] and [5][6] reveal for all complexes a pseudo-tetrahedral piano-stool geometry with ruthenium-tin bonds ranging from 2.56 (anionic complexes) to 2.60 Å (cationic complex).     

Chiral copper-bipyridine complexes: Synthesis, characterization and mechanistic studies on asymmetric cyclopropanation

Chiral bipyridine ligands of different steric properties when reacted with CuCl₂ formed orange, yellow or green solids of new copper(II) complexes, [Cu(L)Cl₂] (L = L2-6), in good yield. Together with [Cu(L1)Cl₂], these complexes were characterized in solution by UV-Vis spectroscopy and cyclic voltammetry. The complexes give d-d transitions between 860 and 970 nm, and exhibit one quasi-reversible Cu(II)/Cu(I) couple between +0.405 V and +0.516 V versus NHE. Two of the copper(II) complexes, [Cu(L5)Cl₂] and [Cu(L6)Cl₂], and a copper(I) complex of L1, [Cu(L1)Cl], were characterized by X-ray crystallography. The triflate derivatives of both the Cu(I) and Cu(II) complexes are active catalysts towards the cyclopropanation of ethyl diazoacetate with styrene. The asymmetric induction suffers when the size difference between the alkyl and alkoxyl groups was minimized. The mechanism of the cyclopropanation was studied with kinetic and competition experiments. The rate is first order in catalyst and ethyl diazoacetate, inverse order with styrene and is strongly affected by the counterion.     

Synthesis and spectral studies on heterobimetallic complexes of manganese and ruthenium derived from N-(2-hydroxynaphthalen-1-yl)methylenebenzoylhydrazide

The complex [Mn^IV(napbh)₂] (napbhH₂ = N-(2-hydroxynaphthalen-1-yl)methylenebenzoylhydrazide) reacts with activated ruthenium(III) chloride in methanol in 1 : 1.2 molar ratio under reflux, giving heterobimetallic complexes, [Mn^IV(napbh)₂Ru^IIICl₃(H₂O)] · [Ru^III(napbhH)Cl₂(H₂O)] reacts with Mn(OAc)₂·4H₂O in methanol in 1 : 1.2 molar ratio under reflux to give [Ru^III(napbhH)Cl₂(H₂O)Mn^II(OAc)₂]. Replacement of aquo in these heterobimetallic complexes has been observed when the reactions are carried out in the presence of pyridine (py), 3-picoline (3-pic), or 4-picoline (4-pic). The molar conductances for these complexes in DMF indicates 1 : 1 electrolytes. Magnetic moment values suggest that these heterobimetallic complexes contain Mn^IV and Ru^III or Ru^III and Mn^II in the same structural unit. Electronic spectral studies suggest six coordinate metal ions. IR spectra reveal that the napbhH₂ ligand coordinates in its enol form to Mn^IV and bridges to Ru^III and in the keto form to Ru^III and bridging to Mn^II.     

Synthesis of chiral chelating N-heterocyclic carbene complexes of ruthenium

The first 9-membered chiral chelating bidentate imidazol-2-ylidene ruthenium (II) benzylidene complexes based on a cyclopentane backbone were synthesised and characterised via NMR and HRMS.     

Synthesis,spectral, and catalytic studies of ruthenium(II) unsymmetrical Schiff-base complexes

Unsymmetrically-substituted ruthenium(II) Schiff-base complexes, [Ru(CO)(B)(L ^x )] [B = PPh₃, AsPh₃ or Py; L ^x = dianion of tetradentate unsymmetrical Schiff-base ligand; x = 4–7, L⁴ = salen-o-hyac, L⁵ = valen-o-hyac, L⁶ = salphen-o-hyac, L⁷ = valen-2-hacn], were prepared and characterized by analytical, IR, electronic, and ¹H NMR spectral studies. The new complexes were tested for their catalytic activity towards the oxidation of benzylalcohol to benzaldehyde.     

Synthesis and X-ray structures of some mono- and binuclear ruthenium complexes with bisphosphine ligands

Summary The dinuclear complexes {RuCp*(-Cl)}₂(-dppm) (1) and {RuCp*(-Cl)}₂ (-dppe) (3) are obtained by reacting [RuCp*(³-Cl)]₄ withdppm, anddppe, respectively.1 is readily oxidized with AgCF₃SO₃, instead of chloride abstraction, to afford the dinuclear complex [{RuCp*(-Cl)}₂(-dppm)](SO₃CF₃)₂ (2) with two metal centers connected by a single Ru-Ru bond. Under the same conditions,3 decomposes to several intractable materials. Similarly to1, RuCp* (dmpe)Cl reacts with AgCF₃SO₃ to afford the Ru(III) complex [RuCp*(dmpe)Cl](SO₃CF₃) (4) without no halide abstraction. The crystal structures of2,3, and4 are presented.

---

Synthese und Röntgenstrukturanalyse einiger ein- und zweikerniger Rutheniumkomplexe mit Bisphosphinliganden

Zusammenfassung Die Komplexe {RuCp*(-Cl)}₂(-dppm) (1) und {RuCp*(-Cl₂(-dppe) (3) wurden durch Umsetzung von [RuCp*(³-Cl)]₄ mitdppm bzw.dppe dargestellt.1 wird durch AgCF₃SO₃ zum zweikernigen Komplex [{RuCp*(-Cl)}₂(-dppm)](SO₃CF₃)₂ (2) oxidiert, welcher eine Ru-Ru-Metallbindung aufweist. Unter den gleiche Reaktionsbedingungen zersetzt sich3 zu undefinierten Produkten. Analog zu1 reagiert RuCp* (dmpe)Cl mit AgCF₃SO₃ zum Ru(III)-Komplex [Ru(Cp*)(dmpe)Cl](SO₃CF₃) (4) wobei es zu keiner Chloridabspaltung kommt. Von2,3, und4 wurden die Kristallstrukturen bestimmt.

     

Preparation of hydride complexes of ruthenium with bidentate phosphite ligands

Hydride complex RuH₂(PFFP)₂ (1) [PFFP = (CF₃CH₂O)₂PN(CH₃)N(CH₃)P(OCH₂CF₃)₂] was prepared by allowing the compound RuCl₄(bpy) · H₂O (bpy = 1,2-bipyridine) to react first with the phosphite PFFP and then with NaBH₄. Chloro-complex RuCl₂(PFFP)₂ (2) was also prepared, either by reacting RuCl₄(bpy) · H₂O with PFFP and zinc dust or by substituting triphenylphosphine with PFFP in the precursor complex RuCl₂(PPh₃)₃. Hydride derivative RuH₂(POOP)₂ (3) (POOP = Ph₂POCH₂CH₂OPPh₂) was prepared by reacting compound RuCl₃(AsPh₃)₂(CH₃OH) first with the phosphite POOP and then with NaBH₄. Depending on experimental conditions, treatment of carbonylated solutions of RuCl₃ · 3H₂O with POOP yields either the cis- or trans-RuCl₂(CO)(PHPh₂)(POOP) (4) derivative. Reaction of both cis- and trans-4 with LiAlH₄ in thf affords dihydride complex RuH₂(CO)(PHPh₂)(POOP) (5). Chloro-complex all-trans-RuCl₂(CO)₂(PPh₂OMe)₂ (6) was obtained by reacting carbonylated solutions of RuCl₃ · 3H₂O in methanol with POOP. Treatment of chloro-complex 6 with NaBH₄ in ethanol yielded hydride derivative all-trans-RuH₂(CO)₂(PPh₂OMe)₂ (7). The complexes were characterised spectroscopically and the X-ray crystal structures of complexes 1, 3, cis-4 and 6 were determined.     

Syntheses and characterization of novel ruthenium complexes based on 1,3-dicyanobenzene

The syntheses and full characterization of novel ruthenium complexes based on 1,3-dicyanobenzene are described. Crystal structures are reported for both [1,3-(cis-RuCl(P(CH₃)₃)₄NC)₂C₆H₄][PF₆]₂ (1cis) and [1,3-(trans-RuCl(dppe)₂NC)₂C₆H₄][H₂PO₄]₂ (3′). Ligand substitution in the homobimetallic complex (3) leads easily to the monometallic analogue, [1,3-(trans-RuCl(dppe)₂NC)C₆H₄(CN)][PF₆] (4). A heterobimetallic complex, [1,3-(trans-RuCl(dppe)₂NC)C₆H₄(CN-FeCp(dppe))][PF₆]₂ (5), of satisfactory purity is also obtained.     

Diruthenium(I,I) saccharinate complexes: Synthesis, molecular structure, and evaluation as catalysts for carbenoid reactions of diazoacetates

The dinuclear ruthenium complexes [Ru₂(μ-sac)₂(CO)₆] (1), [Ru₂(μ-sac)₂(CH₃CN)₂(CO)₄] (3), [Ru₂(μ-sac)₂(CO)₅(PPh₃)] (4) and [Ru₂(μ-sac)₂(CO)₄(PPh₃)₂] (5) as well as the tetranuclear ruthenium complex [Ru₂(μ-sac)₂(CO)₅]₂ (2) (sac = saccharinate, C₇H₄NO₃S⁻) were synthesized starting from Ru₃(CO)₁₂ and saccharin. X-ray crystal structure analysis of 1, 3A × p-xylene, 4 × CH₂Cl₂ and 5 × 3CH₂Cl₂ showed that the core is bridged through the amidate moieties of the two saccharinate ligands, with a head-tail arrangement in complexes 1, 3A and 5, and a head-head arrangement in 4. For complex 3, an equilibrium mixture of the head-head regioisomer 3A and a second species 3b exists in solution. Complexes 1 and 2 are suitable catalysts for the cyclopropanation of nucleophilic alkenes (styrene, cyclohexene and 2-methyl-2-butene) with methyl diazoacetate.     

Synthesis and characterization of electrochemiluminescent ruthenium(II) complexes containing o-phenanthroline and various alpha-diimine ligands

A series of o-phenanthroline-substituted ruthenium(II) complexes containing 2,2′-dipyridyl, 2-(2-pyridyl)benzimidazole, 2-(2-pyridyl)-N-methylbenzimidazole, 4-carboxymethyl-4′-methyl-2,2′-dipyridyl, and/or 4,4′-dimethyl-2,2′-dipyridyl ligands were synthesized and examined as potent electrochemiluminescent (ECL) materials. The characteristics of these complexes, regarding their electrochemical redox potentials and relative ECL intensities for tripropylamine were studied. As found in a 2,2′-bipyridyl-substituted ruthenium(II) complexes, a good correlation between the observed ECL intensity and the donor ability of α-diimine ligands was observed, i.e., the ECL intensity of the Ru(II) complex decreased with an increase in the ligand donor ability. The ECL efficiency increased as the number of substitutions of o-phenanthroline (o-phen) to metal complexes increased.     

Synthesis and catalytic properties of novel ruthenium N-heterocyclic-carbene complexes

The reaction of [RuCl₂(p-cymene)]₂ with 1,3-dialkylimidazolinium salts 1a–f in the presence of a small excess of cesium carbonate yields chelated η⁶-arene, η¹-carbene ruthenium complexes 2a–f. All synthesised compounds were characterized by elemental analysis, NMR spectroscopy. The catalytic activity of RuCl₂(η⁶-arene, η¹-imidazolinylidene) complexes 2a–f was evaluated in the direct arylation of 2-phenylpyridine with chlorobenzene derivatives.     

Synthesis and spectral characterization of 2'-hydroxy chalconate complexes of ruthenium(II) and their catalytic and biological applications

The reactions of [RuHCl(CO)(B)(EPh(3))(2)] (B=EPh(3) or pyridine; E=P or As) and 2'-hydroxychalcones in 1:2 ratio led to the formation of [Ru(CO)(B)(L)(2)] (B=PPh(3), AsPh(3) or Py; L=2'-hydroxychalcones). The new complexes have been characterized by analytical and spectral (IR, electronic and (1)H NMR) data. They have been assigned an octahedral structure. The new complexes were found to catalyze the oxidation of alcohols to aldehydes using N-methylmorpholine-N-oxide as co-oxidant. All the new complexes were found to be active against bacteria such as E. coli, Salmonella typhi and fungi Aspergillus niger. The activity was compared with standard Streptomycin or Bavistin.     

Synthesis of chiral-at-metal half-sandwich ruthenium(II) complexes with the CpH(PNMent) tripod ligand

Treatment of the chiral tripod ligand (L_Ment,S_C)-CpH(PN_Ment) with (Ph₃P)₃RuCl₂ in ethanol afforded the two chiral-at-metal diastereomers (L_Ment,S_C,R_Ru)- and (L_Ment,S_C,S_Ru)-[Cp(PN_Ment)Ru(PPh₃)Cl] (70% de) in which the cyclopentadienyl group and the P atom of the ligand coordinated at the metal center. The (L_Ment,S_C,R_Ru)-diastereomer was isolated by crystallization from ethanol-pentane and its structure was established by X-ray crystallography. The (L_Ment,S_C,R_Ru)-diastereomer epimerized in CDCl₃ solution at 60 °C in a first-order reaction with a half-life of 5.66 h. In alcoholic solution epimerization occurred at room temperature. Substitution of the chloride ligand in (L_Ment,S_C,R_Ru)- and (L_Ment,S_C,S_Ru)-[Cp(PN_Ment)Ru(PPh₃)Cl] by nitriles NCR (R = Me, Ph, CH₂Ph) in the presence of NH₄PF₆ gave mixtures of the diastereomers (L_Ment,S_C,R_Ru)- and (L_Ment,S_C,S_Ru)-[Cp(PN_Ment)Ru(PPh₃)NCR]PF₆. Treatment of (L_Ment,S_C,R_Ru)- and (L_Ment,S_C,S_Ru)-[Cp(PN_Ment)Ru(PPh₃)Cl] with piperidine or morpholine in the presence of NH₄PF₆ led to the chiral-at-metal diastereomers (L_Ment,S_C,R_Ru)- and (L_Ment,S_C,S_Ru)-[Cp(PN_Ment)Ru(PPh₃)NH₃]PF₆ (6% de).     

Synthesis,characterization, and antitumor properties of ruthenium(II) anthraquinone complexes

Three new Ru(II) complexes, [Ru(dmb)₂(ipad)](ClO₄)₂ (dmb = 4,4′-dimethyl-2,2′-bipyridine, ipad = 2-(anthracene-9,10-dione-2-yl) imidazo[4,5-f][1,10]phenanthroline, 1), [Ru(dmp)₂(ipad)](ClO₄)₂ (dmp = 2,9-dimethyl-1,10-phenanthroline, 2), and [Ru(dip)₂(ipad)](ClO₄)₂ (dip = 4,7-diphenyl-1,10-phenanthroline, 3), have been synthesized and characterized. The three Ru(II) complexes intercalate with the base pairs of DNA. The in vitro antiproliferative activities and apoptosis-inducing characteristics of these complexes were investigated. The complexes exhibited cytotoxicity against various human cancer cell lines. BEL-7402 cells displayed the highest sensitivity to 1, accounted for by the greatest cellular uptake. Complex 1 was shown to accumulate preferentially in the nuclei of BEL-7402 cells and cause DNA damage and induce apoptosis, which involved cell cycle arrest and reactive oxygen species generation.     

Arene ruthenium bis-saccharinato complexes: Synthesis, molecular structure and catalytic oxidation properties in aqueous solution

Arene ruthenium complexes [(η⁶-arene)Ru(sacc)₂(OH₂)] (arene = para-cymeme, benzene) containing an aqua and two saccharinato ligands have been synthesized from [(η⁶-arene)RuCl₂]₂ and sodium saccharinate in a water-ethanol mixture (1:1). The aqua complex [(η⁶-MeC₆H₄Prⁱ)Ru(sacc)₂(OH₂)] reacts with acetonitrile to give the acetonitrile complex [(η⁶-MeC₆H₄Prⁱ)Ru(sacc)₂(NCMe)]. The corresponding benzene derivative [(η⁶-C₆H₆)Ru(sacc)₂(NCMe)] was obtained from [(η⁶-C₆H₆)RuCl₂]₂ and saccNa in an acetonitrile-methanol mixture (1:1). All new complexes show a piano-stool geometry with two mono-hapto nitrogen-bonded saccharinato ligands in addition to a H₂O or MeCN ligand. All complexes of the type [(η⁶-arene)Ru(sacc)₂(OH₂)] and [(η⁶-arene)Ru(sacc)₂(NCMe)] were found to catalyze the oxidation of secondary alcohols with tert-butyl hydroperoxide (Bu^tOOH) to give the corresponding ketones in aqueous solution.     

Spectral,catalytic, and antifungal studies of ruthenium(II) chalcone complexes

Reactions of [RuHCl(CO)(B)(EPh₃)₂] (B = EPh₃ or Py; E = P or As) and chalcones in benzene with equal molar ratio led to the formation of new complexes of the type [RuCl(CO)(EPh₃)(B)(L^1?4)] (B = PPh₃, AsPh₃ or Py; E = P or As; L = chalcone). The new complexes have been characterized by analytical and spectroscopic (IR-, electronic, ¹H-, ³¹P-, and ¹³C-NMR) data. Based on these data, an octahedral structure has been assigned for all the complexes. The chalcones are monobasic bidentate (O,O) donors and coordinate to ruthenium via phenolic and carbonyl oxygen. The new complexes exhibit efficient catalytic activity for the transfer hydrogenation of carbonyl compounds. Antifungal properties of the ligands and their complexes have been examined and compared with standard Bavistin.     

Synthesis, crystal, molecular and electronic structures of ruthenium complexes with a benzoxazole derivative ligand

[RuCl₂(HBO)(PPh₃)₂] and [RuCl(CO)(HBO)(PPh₃)₂] complexes with the 2-(2-hydroxyphenyl)benzoxazole (C₁₃H₉NO₂) ligand were synthesized and characterized by infra red, proton and phosphorus nuclear magnetic resonances, electronic absorption and emission spectroscopies and X-ray crystallography. The experimental studies were completed by theoretical calculations. The calculations show that the donor properties of the carbonyl group predominates the π-acceptor ability in the ruthenium(II) complex. The small transfer of electron density to the acceptor π^∗ carbonyl orbitals is compensated by the presence of the chloride acceptor ligand. The electronic structures of these complexes, presented in particular by density of states diagrams, have been correlated with their ability to fluorescence and have been used to analyze the UV-Vis spectra.