Electrochemical and Photochemical Conversion of [Ru3Ir(μ 3-H)(CO)13] into [Ru3Ir(μ-H)3(CO)12]

Electrochemical and photochemical properties of the tetrahedral cluster [Ru₃Ir( ₃-H)(CO)₁₃] were studied in order to prove whether the previously established thermal conversion of this cluster into the hydrogenated derivative [Ru₃Ir(-H)₃(CO)₁₂] also occurs by means of redox or photochemical activation. Two-electron reduction of [Ru₃Ir( ₃-H)(CO)₁₃] results in the loss of CO and concomitant formation of the dianion [Ru₃Ir( ₃-H)(CO)₁₂]^2–. The latter reduction product is stable in CH₂Cl₂ at low temperatures but becomes partly protonated above 283K into the anion [Ru₃Ir(-H)₂(CO)₁₂]^– by traces of water. The dianion [Ru₃Ir( ₃-H)(CO)₁₂]^2– is also the product of the electrochemical reduction of [Ru₃Ir(-H)₃(CO)₁₂] accompanied by the loss of H₂. Stepwise deprotonation of [Ru₃Ir(-H)₃(CO)₁₂] with Et₄NOH yields [Ru₃Ir(-H)₂(CO)₁₂]^– and [Ru₃Ir( ₃-H)(CO)₁₂]^2–. Reverse protonation of the anionic clusters can be achieved, e.g., with trifluoromethylsulfonic acid. Thus, the electrochemical conversion of [Ru₃Ir( ₃-H)(CO)₁₃] into [Ru₃Ir(-H)₃(CO)₁₂] is feasible, demanding separate two-electron reduction and protonation steps. Irradiation into the visible absorption band of [Ru₃Ir( ₃-H)(CO)₁₃] in hexane does not induce any significant photochemical conversion. Irradiation of this cluster in the presence of CO with _irr>340nm, however, triggers its efficient photofragmentation into reactive unsaturated ruthenium and iridium carbonyl fragments. These fragments are either stabilised by dissolved CO or undergo reclusterification to give homonuclear clusters. Most importantly, in H₂-saturated hexane, [Ru₃Ir( ₃-H)(CO)₁₃] converts selectively into the [Ru₃Ir(-H)₃(CO)₁₂] photoproduct. This conversion is particularly efficient at _irr >340nm.     

The reaction of [Ru10C(CO)24][ppn]2 with carbon monoxide to yield [Ru3(CO)12] and [Ru6C(CO)16]2−

The dianion [Ru₁₀C(CO)₂₄]²⁻ in CH₂Cl₂ reacts with CO under ambient conditions to produce quantitative amounts of the species [Ru₃(CO)₁₂] and [Ru₆C(CO)₁₆]²⁻; the hydrido-anion [HRu₁₀C(CO)₂₄]⁻ reacts similarly to form [Ru₆C(CO)₁₆]⁻.     

Reactions of the Cluster Anion [HRu3(CO)11)]− with Dicyclohexylphosphine: Synthesis and Molecular Structure of H2Ru3(CO)8(PCy2)2 and H2Ru3(CO)6(PCy2)2(HPCy2)2

The cluster anion [HRu₃(CO)₁₁]^- (1) reacts with dicyclohexylphosphine in THF solution to give the anionic derivative [HRu₃(CO)₈(PCy₂)₂]^- (2), protonation of which yields the neutral cluster H₂Ru₃(CO)₈(PCy₂)₂ (3) and, in the presence of excess phosphine, HRu₃(CO)₇(PCy₂)₃ (4). In protic methanol as reaction medium, the reaction of 1 with HPCy₂ gives directly the neutral complex H₂Ru₃(CO)₆(PCy₂)₂(HPCy₂)₂ (5), together with 4. The single-crystal structure X-ray analysis of 3 shows a closed triangular Ru₃ framework. The electron count is in accordance with the EAN rule, but the structure analysis of 5 reveals an open, almost linear Ru₃ skeleton, which is electron-deficient with respect to the EAN rule.     

Synthesis and characterisation of novel selenium-containing clusters; crystal structures of [Ru4(μ4-Se)2(CO)8(μ-CO)3] and [Ru3(μ3-Se)2(CO)7(Ph2P(CH2)3PPh2)]

The compound [Ru₄(μ-Se)₂(CO)₈(μ3-CO)₃] (1), has been obtained in good yield by vacuum pyrolysis of [RU₃(CO)₁₂] with [Ph₂Se₂] at 185°C. Reaction of 1 with 1,3-bis(diphenylphosphino)propane at room temperature affords the novel cluster [RU₃(μ₃-Se)₂(CO)₇(Ph₂P(CH₂)₃PPh₂)] (2). The structures of 1 and 2 have been determined by an X-ray diffraction study.     

The first decaruthenium hydrido cluster: synthesis and crystal structure of [N(PPh3)2]2[Ru10C(CO)24]·C6H14 and [N(PPh3)2][HRu10C(CO)24]

X-ray structural studies of new thermolysis products from the reaction of Ru₃(CO)₁₂ in heptane in the presence of 1,3,5-trimethylbenzene (mesitylene) confirm that they are the decaruthenium carbido-cluster dianion [Ru₁₀C(CO)₂₄]²⁻ (I) and the hydrido decaruthenium carbido-cluster monoanion [HRu₁₀C(CO)₂₄]⁻ (II). Both anions have the giant tetrahedron Ru₁₀ metal framework, and the monohydride provides the first example of a hydrido ligand in a tetrahedral Ru₄ cavity.     

New electron-deficient alkene and alkyne derivatives of Ru5(μ5-C)(CO)15: The syntheses and crystal structure analyses of Ru5(μ5-C)(CO)13 [C2H2(CO2Me)2] and Ru5(μ5-C)(CO)15 [C2(CO2Me)2]

Treatment of carbido cluster Ru₅(μ ₅-C)(CO)₁₅ with Me₃NO in acetonitrile solution followed by addition of dimethyl maleate or dimethyl acetylene dicarboxylate affords new clusters Ru₅(μ ₅-C)(CO)₁₃[C₂H₂(CO₂Me)₂] (1) and Ru₅(μ ₅-C)(CO)₁₅[C₂(CO₂Me)₂] (2), respectively. Single crystal X-ray structural studies reveal that both complexes contain a wingtip-bridged butterfly pentametallic skeleton. In complex1 the maleate fragment is coordinated to one wingtip Ru atom through its carbon-carbon double bond and to the adjacent Ru atom by the formation of two O → Ru dative bonding interactions, while the acetylene dicarboxylate fragment in2 is best considered as acis-dimetallated alkene, linking one hinge Ru atom and the nearby Ru atom at the bridged position. Crystal data for1: space group P 4₂/n;a=20.199(6),c=13.941(3) Å,Z=8; finalR _F=0.025,R _w=0.026 for 3963 reflections withI>2σ(I). Crystal data for2: space group P2₁/n;a=9.634(3),b=20.062(6),c=17.372(5) Å,β=90.62(2)°,Z=4; finalR _F=0 033,R _w=0.036 for 4683 reflections withI>3σ(I).     

[Ru(NH3)6](MoO4)Cl·3H2O and [M(NH3)6](ReO4)3·2H2O (M = Ru, Ir). Synthesis and crystal structure

X-ray crystallographic analysis is used to determine the crystal structures of [Ru(NH₃)₆](MoO₄)Cl·3H₂O and [M(NH₃)₆](ReO₄)₃·2H₂O (M = Ru, Ir) complex salts. The features of the fragment packing are studied.     

Isolation of Bis- and Mono-Cyclometallated Ru−IMes Complexes upon Reaction of [Ru(PPh3)3HCl], IMes and ZnMe2

Addition of an excess of ZnMe₂ to a mixture of [Ru(PPh₃)₃HCl] and IMes (IMes=1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene) yields the bis-cyclometallated complex, [Ru(IMes)“(PPh₃)₂] 2 , together with the mono-cyclometallated, Ru−Zn heterobimetallic complex [Ru(IMes)′(PPh₃)₂(ZnMe)] 3 . Treatment of 2 with H₂, PhSiH₃ or pinacolborane yields the previously reported complex, [Ru(IMes)′(PPh₃)₂H] 1 , the synthesis of which has been reinvestigated. Further studies of small molecule reactivity show that 1 adds H₂ to give [Ru(IMes)(PPh₃)₂H₄] 4 , whilst 2 reacts with catecholborane to give [Ru(IMes-Bcat)′(PPh₃)₂H] 5 , in which (IMes-Bcat)′ signifies a borylated NHC ligand that is singly-metallated onto Ru. Treatment of 2 with CO gives the 18-electron dicarbonyl product [Ru(IMes)”(PPh₃)(CO)₂] 6 . Compounds 1 – 3 , 5 and 6 have been structurally characterised.     

The preparation and structure of the tetranuclear ruthenium cluster [Ru4(CO)10(μ2-Cl)2(μ3-OEt)2]

The tetranuclear ruthenium cluster [Ru₄(CO)₁₀Cl₂(OEt)₂] has been prepared in low yield by the reaction of [Ru₃(CO)₁₂] with [N(PPh₃)₂]Cl in refluxing EtOH, followed by oxidation with either [NO][BF₄] or Ag[ClO₄]. A single-crystal X-ray analysis of the complex shows that the four metal atoms adopt a planar geometry with one ruthenium bonded by two μ₂-Cl ligands and two μ₃-OEt ligands to a trinuclear fragment. This complex crystallises in the monoclinic space group I2/c, with a 14.458(3), b 22.073(6), c 15.302(4) Å, β 99.54(2)°, Z = 8; 3113 observed data with F > 3σ(F) were refined by blocked full-matrix least squares to R = 0.031, R_w = 0.034.     

Cluster chemistry: XXXXVIII. Some reactions of Ru3(CO)12 with nitrogen heterocycles. X-ray crystal structures of Ru3(μ-CO)2(CO)8(bipy) and Ru3(μ-H){μ-N2C3H(CF3)2-3,5}(CO)10

Reactions between Ru₃(CO)₁₂ and the nitrogen heterocycles pyridine, 2,2′-bi-pyridyl, pyrazole, 3,5-dimethylpyrazole and 3,5-bis(trifluoromethyl)pyrazole are described. Pyridine afforded the cyclometallated complex Ru₃(μ-H)(μ-NC₅H₄)(CO)₁₀, which with excess pyridine formed Ru₃(μ-H)₂(μ-NC₅H₄)₂(CO)₈. 2,2′-Bipyridyl gave purple Ru₃(μ-CO)₂(CO)₈(bipy), shown by an X-ray structure to have an Fe₃(CO)₁₂-type structure, with the bipy chelating one of the CO-bridged Ru atoms. The pyrazoles gave Ru₃(μ-H)(μ-N₂CP₃HR₂)(CO)₁₀ (R = H, Me or CF₃), in which the pyrazolide ligand spans an RuRu bond also bridged by H, as shown by the X-ray structure of the CF₃ derivative. The bipyridyl and pyrazole complexes both crystallise in the monoclinic system, the former in space group P2₁/n with unit cell dimensions a 7.834(2), b 25.818(2), c 11.717(1) Å, β 107.41(1)° with Z = 4 and the latter in space group P2₁/c, unit cell dimensions a 16.802(3), b 7.726(1), c 18.807(3) Å, β 114.24(1)° with Z = 4. The structures were refined by conventional least-squares methods with the use of 3336 (2993 for the pyrazole structure) reflections with I > 2.5σ(I) to final R = 0.031 and R_w = 0.034 (0.025 and 0.026).     

Hydride addition to Ru3(CO)12. Synthesis and characterization of the transient formyl cluster complex Ru3(CO)11(CHO)−

The reaction of Ru₃(CO)₁₂ (1) with LiEt₃BH at −78°C affords the transient cluster formyl complex Ru₃(CO)₁₁(CHO)⁻ (2) which is observed to decompose by CO loss to give the known hydride cluster Ru₃(CO)₁₁(H)⁻ (3) rapidly at temperatures above −50°C. The formyl cluster has been characterized by low temperature FT-IR, ¹H and ¹³C NMR measurements. Formyl trapping experiments and the effect of Bu₃SnH on the rate of formyl decomposition are briefly described.     

Cluster synthesis 37—Platinum-ruthenium carbido-cluster complexes: The syntheses and structural characterizations of PtRu5(C)(CO)16, Pt2Ru5(C)(CO)13(COD)2, and Pt3Ru5(C)(CO)14(COD)2

From the reaction of [Ru₅(C)(CO)₁₄]^2– with Pt(COD)Cl₂, COD=1, 5 cyclooctadiene, the new platinum-ruthenium carbido cluster complex PtRu₅ (C)(CO)₁₄(COD),1, was obtained in 41% yield. When1 was allowed to react with carbon monoxide (25°C/1 atm), the new complex PtRu₅(C)(CO)₁₆,2, was obtained almost quantitatively (97% yield). Compound2 was characterized by IR and single-crystal X-ray diffraction analysis. The six metal atoms are arranged in the form of an octahedron with the carbide ligand located in the center. Compound1 is believed to have a similar structure to2 except for a COD ligand coordinated to the platinum atom. When activated by treatment with Me₃NO, compound2 reacts with Pt(COD)₂ at 25°C to yield two higher nuclearity cluster complexes, Pt₂Ru₅C(CO)₁₃(COD)₂.3, and Pt₃Ru₅C(CO)₁₄(COD)₂,4. The structure of3 is similar to that of1, but contains a Pt(COD) grouping capping one Ru₃ triangle of the PtRu₅ octahedron. The structure of4 consists of a PtRu₅ octahedron with two Pt(COD) capping groups, one on an Ru₃ triangle and the other on a PtRu₂ triangle of the octahedron. Crystal data: for2, space group=P2₁/n,a=9.341 (2) Å,b=14.957 (3) Å,c=36.80 (1) Å, =90.38 (2) °,Z=8, 4034 reflections,R=0.030, for3, space group=P2₁/c,a=14.998 (3) Å,b=10.288 (3) Å,c=26.581 (7) Å, =102.75 (2) °,Z=4, 2917 reflections,R=0.028. for4, space group=P2₁/n,a=13.412 (4) Å,b=16.252 (4) Å,c=20.107 (4) Å, =106.13 (2) °,Z=4, 2745 reflections,R=0.032.     

Synthesis, DNA-binding and photocleavage studies of ruthenium(Ⅱ) complexes [Ru(btz)_3]~(2+) and [Ru(btz)(dppz)_2]~(2+)

Two new ruthenium(Ⅱ) complexes, [Ru(btz)3](ClO4)2 (1) and [Ru(btz)(dppz)2](ClO4)2 (2) (btz = 4,4′-bithi-azole, dppz = dipyrido[3,2-a:2′,3′-c]phenazine), have been synthesized and characterized by elemental analysis, 1H NMR, ES-MS and X-ray crystallography. The DNA binding behaviors of two complexes have been studied by spectroscopic and viscosity measurements. The results suggest that complex 1 binds to CT-DNA via an electrostatic mode, while complex 2 via an intercalative mode. Under irradiation at 365 nm,...     

Diphenylphosphine and diphenylphosphido derivatives of [Ru3(μ-H)(μ3-ampy)(CO)9] (Hampy = 2-amino-6-methylpyridine)

The reactions of [Ru₃(μ-H)(μ-ampy)(CO)₉] (1) (Hampy = 2-amino-6-methylpyridine) with one or two equivalents of PPh₂H lead to the complexes [Ru₃(μ-H)(μ₃-ampy)(CO)₈(PPh₂H)] (2) or [Ru₃(μ-H)(μ₃-ampy)(CO)₇(PPh₂H)₂] (3), in which the PPh₂H ligands are cis to the bridging NH fragment and cis to the hydride. Complex 2 can be transformed in refluxing THF into the phosphido-bridged derivative [Ru₃(μ₃-ampy)(μ-PPh₂)(μ-CO)₂(CO)₆] (4), which contains the PPh₂ ligand spanning one of the two RuRu edges unbridged by the amido moiety, and presents an extremely high ³¹P chemical shift of 386.9 ppm. Under similar conditions, complex 3 gives a mixture of two isomers of [Ru₃(μ-H)(μ₃-ampy)(μ-PPh₂)₂(CO)₆] in a 5:1 ratio; the major product (5) has a plane of symmetry, whereas the minor one (6) is asymmetric.     

The Thermolysis of [Ru3(CO)12] in Cyclohexene: Synthesis and Charaterisation of the New Clusters [Ru3H2(CO)9(μ3-η1:η2:η1-C6H8)] and [Ru5(CO)12(μ4-η2-C6H8)(η4-C6H8)]

Thermolysis of [Ru₃(CO)₁₂] in cyclohexene for 24 h affords the complexes [Ru(CO)₃(η⁴-C₆H₈)] (1), [Ru₃H₂(CO)₉(μ₂-η¹:η²:η¹-C₆H₈)] (2), [Ru₄(CO)₁₂(μ₄-C₆H₈)] (3) [Ru₄(CO)₉(μ₄-C₆H₈)(η⁶-C₆H₆)] (4a and 4b, two isomers) and [Ru₅(CO)₁₂(μ₄-η²-C₆H₈)(η⁴-C₆H₈)] (5), where 1, 3, 4a and 4b have been previously characterised as products of the thermolysis of [Ru₃(CO)₁₂] with cyclohexa-1,3-diene. The molecular structures of the new clusters 2 and 5 were determined by single-crystal X-ray crystallography, showing that two conformational polymorphs of 5 exist in the solid state, differing in the orientation of the cyclohexa-1,3-diene ligand on a ruthenium vertex.     

Reaction of [Ru(CO)H(NCMe)2(PPh3)2]ClO4 with 1-hydroxymethyl-3,5-dimethylpyrazole. Formation of an amidine complex. The crystal structure of [Ru(CO)H{NHCMe(Me2pz)}(PPh3)2]ClO4

The reaction between [Ru(CO)H(NCMe)₂(PPh₃)₂]ClO₄ and 1-hydroxymethyl-3,5-dimethylpyrazole has been shown by spectroscopic and X-ray crystallographic methods to give the amidine complex [Ru(CO)H{NHCMe(Me₂pz)}(PPh₃)₂]ClO₄.     

Synthesis and Crystal Structure of[Co3(CO)9(μ3-C)C(O)OCH2]2

The title compound [Co3(CO)9(μ3-C)C(O)OCH2]2 was synthesized by the reaction of [Cl3CC(O)OCH2]2 with Co2(CO)8 at 40～50 ℃. Crystal data: C24H4O22Co6, Mr=997.88, monoclinic, space group P21/n(#14), a=9.330(2), b=15.197(4), c=11.783(4), β=91.16(2)°, V=1670.4(7) 3, Z=2, Dc=1.984 g/cm3, μ(MoKα)=30.01 cm-1, F(000)=972.00, T=293K, final R=0.045, Rw=0.051 for 1936 observed reflections with I＞2σ(I). The structure contains two centrosymmetric dimeric molecules in a unit cell, each of which has two tetrahedral skeletons (CCo3) connected through a C(O)OCH3CH2OC(O) bridge.     

Comparison of the Bonding of Benzene and C60 to a Metal Cluster: Ru3(CO)9(μ3-η2,η 2,η2-C6H6) and Ru3(CO)9(μ3-η2,η2,η2-C60)

The electron distributions and bonding in Ru₃(CO)₉( ³- ², ², ²-C₆H₆) and Ru₃(CO)₉( ³- ², ², ²-C₆₀) are examined via electronic structure calculations in order to compare the nature of ligation of benzene and buckminsterfullerene to the common Ru₃(CO)₉ inorganic cluster. A fragment orbital approach, which is aided by the relatively high symmetry that these molecules possess, reveals important features of the electronic structures of these two systems. Reported crystal structures show that both benzene and C₆₀ are geometrically distorted when bound to the metal cluster fragment, and our ab initio calculations indicate that the energies of these distortions are similar. The experimental Ru–C_fullerene bond lengths are shorter than the corresponding Ru–C_benzene distances and the Ru–Ru bond lengths are longer in the fullerene-bound cluster than for the benzene-ligated cluster. Also, the carbonyl stretching frequencies are slightly higher for Ru₃(CO)₉( ³- ², ², ²-C₆₀) than for Ru₃(CO)₉( ³- ², ², ²-C₆H₆). As a whole, these observations suggest that electron density is being pulled away from the metal centers and CO ligands to form stronger Ru–C_fullerene than Ru–C_benzene bonds. Fenske-Hall molecular orbital calculations show that an important interaction is donation of electron density in the metal–metal bonds to empty orbitals of C₆₀ and C₆H₆. Bonds to the metal cluster that result from this interaction are the second highest occupied orbitals of both systems. A larger amount of density is donated to C₆₀ than to C₆H₆, thus accounting for the longer metal–metal bonds in the fullerene-bound cluster. The principal metal–arene bonding modes are the same in both systems, but the more band-like electronic structure of the fullerene (i.e., the greater number density of donor and acceptor orbitals in a given energy region) as compared to C₆H₆ permits a greater degree of electron flow and stronger bonding between the Ru₃(CO)₉ and C₆₀ fragments. Of significance to the reduction chemistry of M₃(CO)₉( ³- ², ², ²-C₆₀) molecules, the HOMO is largely localized on the metal–carbonyl fragment and the LUMO is largely localized on the C₆₀ portion of the molecule. The localized C₆₀ character of the LUMO is consistent with the similarity of the first two reductions of this class of molecules to the first two reductions of free C₆₀. The set of orbitals above the LUMO shows partial delocalization (in an antibonding sense) to the metal fragment, thus accounting for the relative ease of the third reduction of this class of molecules compared to the third reduction of free C₆₀.     

Solid–Gas Hydrogenation of Hex-3-yne and 1,4-Cyclohexadiene in the Presence of Ru3(CO)9(μ-H)(μ-PPh2), Ru3(CO)10(μ-H)(μ-PPh2), Ru3(CO)7(μ-PPh2)2(C6H4), and Ru4(CO)11(μ4-PPh)(C6H4) Deposited on Pyrex Glass, Silica, and Alumina

The title complexes were tested in the hydrogenation of hex-3-yne and of 1,3- and 1,4-cyclohexadiene (CHD) under solid–gas conditions. The clusters were deposited on three “standard” supports, that is, pyrex glass, alumina, and silica. All the clusters, particularly (μ-H)Ru₃(CO)₁₀(PPh₂), show hydrogenation activity. However, they are not particularly selective toward the formation of monoenes; “disproportionation” of 1,3- and 1,4-CHD to hydrogenated products and benzene also occurs. The hydrogenation activity of the clusters is dependent on their nature, the type of substrate, and the characteristics of the supporting material; silica and pyrex glass are usually more active than alumina. Attempts at detecting the formation of organometallic intermediates or by-products (through IR spectroscopy) were made. HRTEM was used to check for eventual decomposition on some supports.