Ruthenium Complex Ru Research Articles

Synthesis, characterization and aqueous-biphase hydrogenation of olefins by the ruthenium complexes Ru(CO) 3(TPPMS) 2 and RuH 2(CO)(TPPMS) 3

The new water-soluble ruthenium complexes Ru(CO) 3(TPPMS) 2 (I) and RuH 2(CO)(TPPMS) 3 ( II), where TPPMS is the m-sulfophenyldiphenylphosphine (C 6H 5)P( m-C 6H 4SO 3Na) in the sodium salt form, were prepared in highly purity content (90% for I and 95% for II) and characterized by using different spectroscopic techniques. These ruthenium complexes showed high stability and solubility in water, enough for using as a catalyst precursor in the two phase catalytic hydrogenation of 1-hexene, styrene, 1-decene, cyclohexene and allylbenzene under moderate reaction conditions. The similar reaction profile obtained during the hydrogenation of 1-hexene, when each complex are used separately, accompanied with the NMR analysis of the final aqueous phase when Ru(CO) 3(TPPMS) 2 ( I) is used as a catalyst precursor, shows that the Ru(CO) 3(TPPMS) 2 ( I) is transformed selectively to RuH 2(CO)(TPPMS) 3 ( II) during the hydrogenation pathway. The mercury test in independent experiments showed no interference of the Hg with the evolution of the reaction, demonstrating that the catalysis is performed by molecular species and the recycling nature of this complexes is demonstrated during the 1-hexene hydrogenation, where at the end of the catalytic reaction, all metal remains in the aqueous phase indicating no leaching of the ruthenium during the reaction as was proved by atomic absorption experiments.

Fluorometric determination of DNA using a new ruthenium complex Ru(bpy)2PIP(V) as a nucleic acid probe.

A new ligand, 2-phenyl(5-fluoro)imidazo[f]-1,10-phenanthroline (PIP(V)), and its coordination compounds, Ru(bpy)2PIP(V), were synthesized. The fluorescence spectrum of the interaction between Ru(bpy)2PIP(V) and DNA was studied, and a very strong fluorescence peak at a wavelength of 589 nm appeared. The optimum condition of analyzing DNA was decided. The method is simple, convenient and fast, and also has high sensitivity and good selectivity. It has been satisfactorily employed for determinations in synthesized samples.

Synthesis and X-ray Structural Characterization of Ru(PPh3)3(CO)(C2H4) and RuH(o-C6H4C(O)CH3)(PPh3)2L (L = PPh3, CO, DMSO): Ruthenium Complexes with Relevance to the Murai Reaction

The ruthenium complexes Ru(PPh3)3(CO)(C2H4) (1) and RuH(o-C6H4C(O)CH3)(L)(PPh3)2 (2, L = PPh3; 3, L = CO; 4, L = DMSO) have been prepared in order to assess their activity for catalyzing the insertion of alkenes into the ortho C−H bond of aromatic ketones (Murai reaction). Treatment of RuH2(CO)(PPh3)3 with ethene in refluxing toluene afforded 1, which has been characterized by multinuclear NMR spectroscopy and X-ray crystallography. Excess acetophenone reacted with Ru(H2)H2(PPh3)3 to give RuH(o-C6H4C(O)CH3)(PPh3)3 (2), which loses triphenylphosphine upon addition of CO or DMSO to give RuH(o-C6H4C(O)CH3)(CO)(PPh3)2 (3) and RuH(o-C6H4C(O)CH3)(DMSO)(PPh3)2 (4), respectively. The X-ray crystal structures of both of these compounds have been determined. The activity for catalyzing the reaction of 2‘-methylacetophenone with triethoxyvinylsilane follows the order RuH2(CO)(PPh3)3 > 2 > 1 > 4. Complex 3, along with both RuH2(CO)(AsPh3)3 and RuH2(CO)(dppp)(PPh3) (dppp = Ph2P(CH2)3PPh2), show essentially zero cataly...

Electron Transfer Dynamics in Nanocrystalline Titanium Dioxide Solar Cells Sensitized with Ruthenium or Osmium Polypyridyl Complexes

The electron transfer dynamics in solar cells that utilize sensitized nanocrystalline titanium dioxide photoelectrodes and the iodide/triiodide redox couple have been studied on a nanosecond time scale. The ruthenium and osmium bipyridyl complexes Ru(H2L‘)2(CN)2, Os(H2L‘)2(CN)2, Ru(H2L‘)2(NCS)2, and Os(H2L‘)2(NCS)2, where H2L‘ is 4,4‘-dicarboxylic acid 2,2‘-bipyridine, inject electrons into the semiconductor with a rate constant >108 s-1. The effects of excitation intensity, temperature, and applied potential on the recombination reaction were analyzed using a second-order kinetics model. The rates of charge recombination decrease with increasing driving force to the oxidized sensitizer, indicating that charge recombination occurs in the Marcus inverted region. The electronic coupling factors between the oxidized sensitizer and the injected electrons in TiO2 and the reorganization energies for the recombination reaction vary significantly for the different metal complexes. The charge recombination rates a...

Reactions of cis and trans Bcat, Aryl Osmium Complexes (cat = 1,2-O2C6H4). Bis(Bcat) Complexes of Osmium and Ruthenium and a Structural Comparison of cis and trans Isomers of Os(Bcat)I(CO)2(PPh3)2

Reaction of Os(Bcat)Cl(CO)(PPh3)2 (1) (HBcat = catecholborane or 1,3,2-benzodioxaborole) with o-tolyllithium gives the yellow, five-coordinate Bcat, aryl complex Os(Bcat)(o-tolyl)(CO)(PPh3)2 (2). Treatment of 2 with carbon monoxide or p-tolylisocyanide gives the corresponding saturated Bcat, aryl complexes cis-Os(Bcat)(o-tolyl)(CO)2(PPh3)2 (3) and cis-Os(Bcat)(o-tolyl)(CO)(CN-p-tolyl)(PPh3)2 (4). Complexes 3 and 4 decompose in benzene solution at room temperature to give o-tolylBcat and the orthometalated triphenylphosphine complexes (5) and (as a mixture of two isomers, 6a and 6b), respectively. In the presence of B2cat2, 3 and 4 react to give the bis(Bcat) complexes Os(Bcat)2(CO)2(PPh3)2 (7) and Os(Bcat)2(CO)(CN-p-tolyl)(PPh3)2 (8). Complex 3 also reacts with HBcat to produce Os(Bcat)H(CO)2(PPh3)2 (9). The bis(Bcat) ruthenium complexes Ru(Bcat)2(CO)2(PPh3)2 (10) and Ru(Bcat)2(CO)(CN-p-tolyl)(PPh3)2 (11) can be prepared by treatment of Ru(CO)2(PPh3)3 or Ru(CO)(CN-p-tolyl)(PPh3)3 with B2cat2. Complex 3 reacts with Cl2CCCl2 or CHCl3 to produce OsCl(CClCCl2)(CO)2(PPh3)2 (12) or OsCl2(CO)2(PPh3)2, respectively. Complex 1 when treated with CO gives cis-Os(Bcat)Cl(CO)2(PPh3)2 (13), which in turn with phenyllithium or o-tolyllithium gives trans-Os(Bcat)(Ph)(CO)2(PPh3)2 (14) or trans-Os(Bcat)(o-tolyl)(CO)2(PPh3)2 (15). Complex 15 reacts with I2 to give a mixture of trans-Os(Bcat)I(CO)2(PPh3)2 (16) and trans-Os(o-tolyl)I(CO)2(PPh3)2 (17). Complex 16 is also formed by heating cis-Os(Bcat)I(CO)2(PPh3)2 (18) in benzene. Crystal structures of complexes, 5, 8, 10, 11, 12, 16, and 18 are reported.

Redox and photochemical behaviour of ruthenium(II) complexes with H2dcbpy ligand (H2dcbpy = 2,2′-bipyridine-4,4′-dicarboxylic acid)

The electrochemical redox properties of the ruthenium(II) complexes Ru(H2dcbpy)(CO)2Cl21, Ru(H2dcbpy)2Cl22, Ru(H2dcbpy)2Br23, Ru(H2dcbpy)2(dcbpy) 4 and [Ru(H2dcbpy)3]Cl25 [H2dcbpy = 2,2′-bipyridine-4,4′-dicarboxylic acid] were studied in CH3CN and DMSO by cyclic voltammetry. The metal-based RuII–RuIII oxidations are observed at variable positive potentials (E1/2 = 0.15–1.62 V vs. Ag+–Ag). The H2dcbpy ligands withdraw electron density from the ruthenium centre and make the oxidation more difficult (seen as positive shifts in E1/2 values). At negative potentials the first irreversible ligand-based reductions (Epc = −1.37 to −1.57 V) are due to the deprotonation of carboxylic acid groups whereas the subsequent reversible reactions at high negative potentials are assigned as bipyridine ring based reductions. Based on CV and UV-Vis studies, photoirradiation in the co-ordinating solvent (CH3CN) revealed the tendency to light-induced CH3CN co-ordination for complexes 1–5. The photochemical products were also identified by using Lever’s E(L) parameters. For example, upon photoirradiation of 1, the principal product is Ru(H2dcbpy)(CO)(CH3CN)Cl2. The structures of 1 and 3–5 were determined by single-crystal X-ray crystallography.

Synthesis and Spectroscopic Characterization of a Zeolite-Entrapped Ru(bpy)(2)(dpp)(2+) Complex.

The heteroleptic ruthenium(II) complex Ru(bpy)(2)(dpp)(2+) (where bpy = 2,2'-bipyridine and dpp = 2,3-bis(2-pyridyl)pyrazine) has been prepared in the supercages of Y-zeolite and characterized by diffuse reflectance, electronic absorption, electronic emission, and resonance Raman (RR) spectroscopy, as well as lifetime measurements. The spectral results confirm the identity of the entrapped complex. The diffuse reflectance spectrum of the zeolite-entrapped complex is slightly red-shifted in the visible region compared to the absorption spectrum of the free complex in water solution. The emission maximum for the zeolite-entrapped complex is red-shifted by 16 nm with respect to the complex in water solution and by 38 nm relative to the complex in acetonitrile solution. The emission maximum for a zeolite surface-adsorbed complex is blue-shifted by 12 nm with respect to the complex in water solution, but the emission maxima of the liberated complex after dissolution of the zeolite matrix, for both the entrapped and adsorbed complexes, are identical to the spectrum of the free complex in water solution. There are moderate RR frequency shifts observed for the zeolite-entrapped complex relative to the solution-phase complex as a consequence of the interaction of the complex with the zeolite framework. The excited state lifetime measurement shows no dramatic changes upon entrapment within the zeolite supercages. Temperature-dependent lifetime measurements indicate that the excited state decays via two thermally accessible upper states.

Syntheses and characterization of a series of carbonylruthenium(I) and (II) complexes containing pyridyl ligands

The reaction of dodecacarbonyltriruthenium (Ru 3(CO) 12) with tris(2-pyridylmethyl)ammonium perchlorate (tpa·3HClO 4) in toluene, in the presence of acetic acid, produced a new ruthenium(II) complex of tpa [Ru(CH 3CO 2)(CO)(tpa)]ClO 4·C 6H 5CH 3 ( 1). A similar reaction of Ru 3(CO) 12 with 2-pyridylcarboxylic acid (pyCO 2H) in toluene yielded a ruthenium(II) complex Ru(pyCO 2) 2(CO) 2 ( 2). A related ruthenium(III) compound, [Ru(pyCO 2) 3]·H 2O ( 3), was obtained from the reaction of RuCl 3· nH 2O and sodium 2-pyridinecarboxylate in a mixture of water and ethanol (1:1 by volume). The reaction of Ru 3(CO) 12, benzoic acid and pyridine (py) in toluene resulted in the formation of a dinuclear ruthenium(I) complex [Ru 2(C 6H 5CO 2) 2(CO) 4(py) 2]·0.5C 6H 5CH 3 ( 4). Compounds 1– 4 have been characterized by IR, NMR and X-ray crystallography.

Comparing structures and reactivity in analogous Fe and Ru complexes. ( iPr-DAB)Fe(CO) 2I 2 and ( iPr-DAB)FeI 2: a perfectly reversible CO-carrier system. (R-DAB= N,N′-R 2-1,4-diaza-1,3-butadiene)

Fe( iPr-DAB)(CO) 3 ( 1a) oxidatively adds I 2 to give ( iPr-DAB)Fe(CO) 2- trans-I 2 ( 2a). Photochemically or thermally, 2a readily dissociates both carbonyl ligands to give tetrahedral Fe( iPr-DAB)I 2 ( 3a). Under an atmosphere of CO, complex 2a is quantitatively regenerated from 3a. The X-ray crystal structures of 2a and 3a have been determined. 2a: triclinic, space group P 1 ̄ , a=8.7624(3), b=9.0550(4), c=10.6512(6) Å, α=95.429(4), β=105.245(4), γ=95.209(3)°, Z=2, R=0.0251. 3a: orthorhombic, space group Aba2, a=11.2693(10), b=15.933(2), c=7.5958(10) Å, Z=4, R=0.036. Contrasting the behaviour of 2a, the analogous ruthenium complexes (R-DAB)Ru(CO) 2 trans-I 2 ( 4) are very stable, and the carbonyl ligands cannot be dissociated thermally. In the dichloro complexes, of which both the kinetic trans- ( 5) and the thermodynamic cis-compounds ( 6) have been isolated, both isomers undergo a photochemical CO mono-substitution to give for example the isolable trans-dichloro methanol complex ( 7).

The formation of σ-phenylethynyl and σ-diphenylbutenynyl complexes in the reaction of σ-alkenyl ruthenium(II) complexes with phenylacetylene. The X-ray structure of a ruthenium(II) complex containing a σ-phenylethynyl ligand

Ruthenium(II) complexes containing both σ-alkenyl and η 2-carboxylate ligands Ru(O 2CR 2)(CHCHR 1)(CO)(PPh 3) 2 (R 1 tBu, Ph; R 2=CHCHCHCHCH 3) react with phenylacetylene in two stages. Their reaction with an equivalent amount of the alkyne led to the formation of a σ-alkynyl-containing ruthenium(II) complex Ru(O 2CR 2)(CCPh)(CO)(PPh 3) 2 (R 2=CHCHCHCHCH 3), the molecular structure of which was established by X-ray diffraction. This σ-alkynyl complex then reacts with phenylacetylene to form a σ-butenynyl-containing compound Ru(O 2CR 2)(C(CCPh)CPhH)(CO)(PPh 3) 2 (R 2=CHCHCHCHCH 3). Both reactions support the key role of alkynyl ligands in the dimerization of alkynes.

Some reactions of the ruthenium allenylidene complex [Ru(CCCPh 2)(PPh 3) 2Cp][PF 6] with nucleophiles

Reactions between [Ru(CCCPh 2)(PPh 3) 2Cp][PF 6] and nucleophilic reagents LiMe, NaOMe, KCN and KC 5H 5 have given the neutral substituted alkynyl–ruthenium complexes Ru{CCCPh 2(Nu)}(PPh 3) 2Cp. The molecular structures of complexes with Nu=OMe, CN and C 5H 5 have been determined.

Chemiluminescence and catalysis of decomposition of dimethyldioxirane adsorbed from the gas phase on silipore containing tris(bipyridyl)ruthenium complex Ru(bpy)3Cl2 and 9,10-diphenylanthracene

The kinetics of decomposition of dimethyldioxirane (DMD) adsorbed from the gas phase on the silipore surface was studied by the chemiluminescence (CL) technique. The lower boundary of the CL yield in the reaction of DMD decomposition (4·10−9 Einstein mol−1) and chemiexcitation yield of methyl acetate (4·10−4) were estimated. Chemiluminescence upon decomposition of DMD on the silipore surface in the presence of activators of CL such as tris(bipyridyl)ruthenium complex Ru(bpy)3Cl2 and 9,10-diphenylanthracene was revealed. Ru(bpy)3Cl2 activates the luminescence according to chemically induced electron exchange mechanism.

Ruthenium(II) Hydrido Complexes of 2,6-(Diphenylphosphinomethyl)pyridine

A series of PNP−ruthenium(II) complexes Ru(OCOMe)2(PNP) (1), Ru(OCOMe)2(PNP)(PPh3) (2), the monohydrides RuHX(PNP)(PPh3) (X = OCOMe (3); X = Cl (4)), and dihydride RuH2(PNP)(PPh3) (5) (PNP = 2,6-bis(diphenylphosphinomethyl)pyridine) were synthesized and characterized by microanalysis as well as NMR, IR, and mass spectroscopies. The solution dynamics of complex 1 were studied by variable-temperature 1H and 31P{1H} NMR spectroscopies. The crystal structure of RuHCl(PNP)(PPh3) (4) was determined by X-ray crystallography, showing that the PNP ligand coordinates the Ru atom in a meridional mode. The hydrido complexes RuH(OCOMe)(PNP)(PPh3) (3) and RuH2(PNP)(PPh3) (5) undergo deuterium exchange reactions with CD3OD to give substitution of both the hydrides and PNP methylene protons by deuterium. The probable intermediates involved in these exchange processes are molecular dihydrogen complexes of Ru(II).

Catalysis of aerobic olefin oxidation by a ruthenium perhaloporphyrin complex

The perhalogenated porphyrin ruthenium complex (TFPPCl 8)Ru(CO) (TFPPCl 8 = octachlorotetrakis(pentafluorophenyl)porphyrin) catalyzes aerobic oxidation of olefins at room temperature. Cyclohexene is oxidized primarily at the allylic position, and styrene primarily to benzaldehyde, indicating a radical autoxidation mechanism. Reactions are enhanced by visible light. Reaction with m-chloroperbenzoic acid converts the ruthenium complex to (TFPPCl 8)Ru(O) 2, but such oxo complexes do not appear to participate in catalytic aerobic oxidation.

Polypyridine Ruthenium(II) Complexes Containing Mixed Ligands. Synthesis, Spectroscopic and Photophysical and Electrochemical Properties

A series of polypyridine Ruthenium(II) complexes Ru(II)(ttp)(L)X×PF 6 were synthesized and characterized, where L are 2,2′-bipyridine(bpy), 4,4′-dimethyl-2,2′-bipyridine(dmpy), 1,10-phenanthroline(phen) and X are Cl −, NCS −, CN −; ttp=4′-p-tolyl-2,2′:6′,2′′-terpyridine. Their redox, spectroscopic and photophysical properties have been studied. All complexes have intense MLCT(d M→π L*) absorbance at approximately 500 nm and were found to be emitting with monoexponential decay of emission intensity at 298 K. The maximum wavelengths of absorbance and emission undergo a blue shift in the order of Cl −, NCS −, CN −. All complexes have an one-electron-oxidative process corresponding to Ru(III)/Ru(II) with a potential of about 0.8 V, and their oxidation potential increased also according to Cl −, NCS −, CN −. Two reversible or quasi-reversible one-electron-reductive processes based on ligands were also observed.

Structure and reactivity of the zero-valent ruthenium complex Ru(1,2-bis(diphenylphosphino)ethane)(CO) 3 and the dicationic ruthenium dimer [Ru 2(1,2-bis(diphenylphosphino)ethane) 2(CO) 6] 2+

The structure of Ru(dppe)(CO) 3 was characterized by single crystal X-ray diffraction [monoclinic crystal system, space group P2 1/ n, a=12.2353(2) Å, b=16.0803(3) Å, c=14.2451(3) Å, β=111.109(1)°, V=2614.62(9) Å 3, Z=4] and found to be intermediate between trigonal bipyramidal and square pyramidal. One electron oxidation of Ru(dppe)(CO) 3 using [( η 5-C 5H 5) 2Fe][PF 6] produced [Ru 2(dppe) 2(CO) 6][PF 6] 2. The dicationic complex was fully characterized by solution spectroscopic methods and by single crystal X-ray diffraction [trigonal crystal system, space group P3 121, a=20.566(2) Å, c=13.871(2) Å, V=5080.7(8) Å 3, Z=3] and found to have a dimeric structure with two octahedral units sharing a common apex via a Ru(I)–Ru(I) single bond. One octahedral unit is rotated approximately 45° relative to the other, and the chelating phosphine ligand occupies sites cis and trans to the Ru(I)–Ru(I) bond. All of the carbonyl ligands were found to be terminal. The dimer was fluxional in solution and line-shape analysis of the 31P{ 1H} and 13C{ 1H} variable-temperature NMR spectra was used to investigate the exchange mechanism and evaluate the rate constants. The mechanism involved an intramolecular, two-site exchange involving pairwise bridging carbonyls and had activation parameters of 11.8±0.15 kcal mol −1 and −6.7±0.6 eu for Δ H ‡ and Δ S ‡ respectively. The dimer exhibited similar thermal and photochemical reactivity patterns; disproportionation occurred in CH 3CN and halogen atom abstraction occurred in halogenated solvents.

Stoichiometric alkyne cyclotrimerization at a ruthenium centre: A new synthetic route to Ru( η6-arene)( η4-cycloocta-1,5-diene) complexes

Alkynes RC 2R′ [R=H, R′=Bu n, CH 2CMeEt, (CH 2) 5C 2H; R=R′=Me, Ph; R=Me, R′=Pr n] undergo stoichiometric cyclotrimerization on reaction with the naphthalene–ruthenium(0) complex Ru( η 6-C 10H 8)( η 4-C 8H 12), 1, at room temperature to give the corresponding Ru( η 6-arene)( η 4-C 8H 12) complexes in moderate to excellent yield. Unsymmetrical alkynes give a mixture of the isomeric η 6-1,3,5- ( a) and η 6-1,2,4-arene ( b) complexes, the ratio a: b being dependent on the electronic and steric effects of R and R′. In the presence of 1, 1-hexyne and 4-methyl-1-hexyne cocyclotrimerize with acetonitrile to give substituted pyridines, which are formed in addition to the Ru( η 6-arene)( η 4-C 8H 12) complexes.

Synthesis, characterization and some catalytic properties of ruthenium complexes Ru(PPh 3) 2Cl 2(L) 2 [L = 4-Bu t-py, 4-vinyl-py, 4-CN-py, 4-Me-py, 3-Me-py, L 2 = 4,4′-bipy]. Kinetics of cyclohexene hydrogenation catalysed by Ru(PPh 3) 2Cl 2(4-Bu t-py) 2

The complexes Ru(PPh 3) 2Cl 2(L) 2 (L = 4-Bu t-py, 4-vinyl-py, 4-CN-py, 4-Me-py, 3-Me-py, L 2 = 4,4′-bipy) have been prepared by reaction of RuCl 2(PPh 3) 3 with the appropriate ligand under mild conditions and characterized by elemental analysis, IR, NMR ( 1H and 31P) and UV-vis spectra; the Ru II derivatives display a RuP 2Cl 2N 2 core with a trans, cis, cis arrangement of the donor atoms. Ru(PPh 3) 2Cl 2(4-Bu t-py) 2 is an efficient catalyst precursor for the homogeneous hydrogenation of cyclohexene and benzaldehyde under moderate conditions. A kinetic study of the hydrogenation of cyclohexene led to a rate law r = k cat[Ru][H 2], which corresponds to a mechanism involving a fast coordination of cyclohexene to an electronically unsaturated hydride RuHCl(PPh 3) 2(4-Bu t-py), followed by a rate-limiting oxidative addition of H 2 and rapid reductive elimination of the product.

Diastereoselective Synthesis, Spectroscopy, and Electrochemistry of Ruthenium(II) Complexes of Substituted Pyrazolylpyridine Ligands.

We report the synthesis of the hetero- and homoleptic ruthenium(II) complexes Ru(bpy)(2)L(2+), Ru(bpy)L(2)(2+) (bpy is 2,2'-bipyridine), and RuL(3)(2+) of six new bidentates L, the substituted pyrazolylpyridines 1-6 (1-substituted-3-(2-pyridinyl)-4,5,6,7-tetrahydroindazoles with substituents R = H, CH(3), Ph, or C(6)H(4)-4"-COOX where X = H, CH(3), or C(2)H(5)). These were fully characterized by (1)H- and (13)C-NMR spectroscopy and elemental analysis. The UV-visible spectra and redox properties of the complexes, some in the ruthenium(III) and reduced bipyridine oxidation states, are also discussed. The substituents R played a role in determining the stereochemistry of the Ru(bpy)L(2)(2+) and RuL(3)(2+) products. The reaction of Ru(DMSO)(4)Cl(2) with 3 equiv of L bearing aromatic substituents gave only meridional RuL(3)(2+) isomers. The one-step reaction of Ru(bpy)Cl(3).H(2)O with 2 equiv of L provided a mixture of the three possible Ru(bpy)L(2)(2+) isomers, from which one symmetric isomer (labeled beta) was isolated pure. A trans arrangement of the pyrazole groups was deduced by (1)H-NMR and confirmed by X-ray crystallography for one such stereomer (beta-[Ru(bpy)(5)(2)](PF(6))(2), R = C(6)H(4)-4"-COOC(2)H(5)). In contrast, Ru(DMSO)(4)Cl(2) reacted with 2 equiv of L and then 1 equiv of bpy to selectively form the other symmetric isomer (labeled alpha) where the pyridine groups of L are trans. Crystal data for beta-[Ru(bpy)(5)(2)](PF(6))(2) (C(52)H(50)N(8)O(4)F(12)P(2)Ru) with Mo Kalpha (lambda = 0.710 73 Å) radiation at 295 K: a = 28.442(13) Å, b = 18.469(15) Å, c = 23.785(9) Å, beta = 116.76(0) degrees, monoclinic, space group C2/c, Z = 8. Fully anisotropic (except for H and disordered F atoms), full-matrix, weighted least-squares refinement on F(2) gave a weighted R on F(2) of 0.2573 corresponding to R on F of 0.1031 for data where F > 4sigma(F ).

Preparation, Properties, and Reactions of Metal‐Containing Hetercycles, XC. Reactivity of Differently Activated Alkynes toward Ruthenium and Osmium Complexes of the Type (η2‐C2H4)M(CO)4

Depending on the substituents, the reaction of the activated alkynes ZC≡CZ (2a‐g) [Z = CO2R: R = Me (a), Et (b); Z = R1: R1 = CF3 (c), CH2Cl (d), CH2Br (e); Z = CH2OC(O)R2: R2 = Me (f), CCl3 (g)] with the labile ruthenium complex (η2‐C2H4)Ru(CO)4 (1) results in the formation of three different types of heterocycles. While the reactions of the dialkyl acet‐ylenedicarboxylates 2a, b lead to the dimeric tricarbonylru‐thenacyclopentadienes 3a, b, being catalytically active in the cyclotrimerization of alkynes like 2a, b, the application of the 1,4‐halogeno‐2‐butynes 2c‐e yields the bicyclic heterocycles 4c‐e. The esters of 2‐butyne‐1,4‐diol 2f, g are converted into the tetracarbonylruthenacyclopentadienes 5f, g. Investigation of the primary attack of the alkynes 2a‐g at complex 1 leads to the conclusion, that an ionic mechanism is preferred in the ruthenium‐catalyzed cyclotrimerization of electron‐poor alkynes. If, instead of 1, (η2‐C2H4)Os(CO)4 (6) is allowed to react with the acetylenes 2a, b the osmium complexes (η4‐C6Z6)Os(CO)3 (7a, b) are isolated. In the presence of CO at 2 bar 7a, b release the benzene derivatives C6Z6 (8a, b) with the formation of Os3(CO)12.