Ru Rh Research Articles

The liquidus surface projection of the scandium-ruthenium-rhodium system in the field of compositions 0–50 at.% Sc

The projection of the liquidus surface of the ScRuRh system (in the field of compositions 0–50 at.% Sc) on the concentrational triangle is plotted using metallography, X-ray diffraction, microprobe and differential thermal analysis data. It has been established, that ternary compounds do not form in the system. Its liquidus surface consists of five surfaces of primary crystallization of ruthenium and rhodium solid solutions as well as of the phases based on ScRu 2, ScRh 3 and the δ phase (a continuous series of solid solutions between isostructural CsCl-type structure phases based on ScRu and ScRh). The highest temperature on the surface is 2334 °C, which corresponds to the melting of pure ruthenium; the lowest temperature is 1520 °C (of the existence of ternary eutectic L F 1 ⇄ δ + 〈ScRh 3〉 + 〈Ru〉).

Four-membered chelate rings in complexes with 2,2-bis(diphenylphosphino)propane. Crystal and molecular structures of trans-[RuCl2{Me2C(PPh2)2}2], [RuCl{Me2C(PPh2)2}(η-C5H5)] and [(η-C5H5)Ru(µ-CO)2-{µ-Me2C(PPh2)2}RhCl2](Rh–Ru)

The compound Me2C(PPh2)2(2,2-dppp) reacted with 0.5 equivalent of [Rh2Cl2(CO)4] to afford monomeric [RhCl(CO)(2,2-dppp-P,P′)]1. Metathesis with LiBr afforded [RhBr(CO)(2,2-dppp-P,P′)]2. With 0.25 equivalent of [Rh2Cl2(CO)4] the rigid, square-planar [Rh(2,2-dppm)2]Cl 3 was formed. These results are in sharp contrast to the chemistry seen with H2C(PPh2)2 and H(Me)C(PPh2)2. With 0.5 equivalent of [RuCl2(PPh3)3], 2,2-dppp reacted to give brown-orange trans-[RuCl2(2,2-dppp)2]4a. In solution this is in equilibrium with a green five-co-ordinate species [RuCl(2,2-dppp)2]Cl 4b, the first such complex to be observed with a four-membered chelating diphosphine. With [RuCl(PPh3)2(η-C5H5)], 2,2-dppp reacted to form [RuCl(2,2-dppp)(η-C5H5)]5. Although its rhodium(I) chemistry suggests that 2,2-dppp favours chelation rather than bridging modes of co-ordination, when 5 was treated with 0.5 equivalent of [Rh2Cl2(CO)4] it readily formed [(η-C5H5)Ru(µ-CO)2(µ-2,2-dppp)RhCl2](Rh–Ru)6. The structures of 4–6 have been determined by X-ray diffraction.

Photoinduced energy and electron transfer in inorganic covalently linked systems

Photoinduced electron transfer and charge recombination can be studied in metal-polypyridine polynuclear complexes based on the (MebpyCH 2CH 2Mebpy) (Me, methyl; bpy,2,2′-bipyridine) bridging ligand. An example is provided by the binuclear complex [Ru(Me 2phen) 2(MebpyCH 2CH 2Mebpy)Rh(Me 2bpy) 2] 5+ (phen, 1,10-phenanthroline) (abbreviated as Ru(II)Rh(III)). In this system, photoinduced electron transfer processes originating from both local excited states (*Ru(II)Rh(III)→Ru(III)Rh(II) and Ru(II)*Rh(III)→Ru(III)Rh(II)), as well as charge recombination (Ru(III)Rh(II)→Ru(II)Rh(III)), have been resolved in the nanosecond and picosecond time domains using transient absorption and emission measurements. An energy transfer process (Ru(II)*Rh(III)→*Ru(II)Rh(III) can also be observed in rigid media, where the competing electron transfer process is suppressed. The factors affecting the kinetics of the various electron transfer steps can be discussed in terms of current transfer theories. Polychromophoric complexes suited for the study of intercomponent energy transfer can be designed using Re(I) and Ru(II) polypyridine units as molecular components and cyanide bridges as connectors. The energy flow in such systems is determined by the relative energy ordering of the metal-to-ligand charge transfer (MLCT) excited states of the various units, which can be controlled synthetically through the type of metal, the type of polypyridine ligand and the binding mode of the bridging cyanide(s). For example, in [NCRu(bpy) 2CNRu(bpy) 2CN] +, the flow is from the C-bonded to the N-bonded (to bridging cyanide) unit; in [(CO) 3Re(phen)NCRu(bpy) 2CN] +, the flow is from Re(I) to Ru(II); in [NCRu(bpy) 2 CNRu(bpy(COO) 2) 2NCRu(bpy) 2CN] 2−, the flow is from the bpy-containing units to the units containing dicarboxy—bpy. With regard to the identification of the lowest energy state in such systems, valuable information can be obtained using vibrational spectroscopies, such as time-resolved IR and resonance Raman. Compounds of this series behave in many respects as supramolecular antenna systems. Applications of the antenna effect to the spectral sensitization of semiconductors are discussed.

Synthesis and structural characterization of a new series of ruthenium(II) complexes containing the short bite Ph 2PPy ligand. Cooperative effect between the anionic rhodium and cationic ruthenium species in the catalytic hydroformylation of styrene by [Ru(Ph 2PPy) 3Cl] [Rh(CO) 2Cl 2

The reaction of [(C 8H 12)RuCl 2] n with 3 molar equiv. of 2-(diphenylphosphino)pyridine, Ph 2PPy, in refluxing methanol, gave [Ru(Ph 2PPy) 3Cl]Cl ( 1) and small amount of a red unidentified product. A fac structure in which one of the Ph 2PPy is γ 1-coordinated and the remaining two are chelated to the ruthenium atom has been assigned to 1 on the basis of 31P{ 1H} NMR spectra. Solutions of 1 in chlorinated solvents afford the neutral complex [Ru(Ph 2PPy) 2Cl 2] ( 2). IR and NMR spectra and X-ray analysis indicate that 2 assumes a cis structure in both solution and solid state. Compound 2 crystallizes with two CDCl 3 molecules H-bonded to the chlorine atoms of the coordination shell of each ruthenium. Crystal data: triclinic, space group P 1 , a=10.608(3), b=14.340(4), c=15.570(5) Å, α=102.06(2), β=105.48(2), γ=108.16(2)°, Z=2. The structure model was refined up to R=0.066 for 3147 reflections with F⩾8σ( F). At 20 °C and 1 atm, compound 1 adds CO in equilibrium condition affording the dicationic compound [Ru(CO)(Ph 2PPy) 3]Cl 2; this cannot be isolated when operating in CO atmosphere. Treatment of 1 with 2 equiv. of CF 3COOAg in dichloromethane gave the corresponding [Ru(Ph 2PPY) 3(CF 3COO)]CF 3COO ( 4) containing a small amount of [Ru(Ph 2PPY) 2(CF 3COO) 2] ( 5). By reacting 1 with [Rh(CO) 2Cl] 2 or [Ir(CO) 2( p-toluidine)Cl] the complexes [Ru(Ph 2PPy) 3Cl][Rh(CO) 2Cl 2] ( 6) and [Ru(Ph 2PPy) 3Cl][Ir(CO) 2Cl 2] ( 7) were obtained. Compounds 6 and 7 were used as catalysts in the hydroformylation of styrene. The hydroformylation reactions were performed in the temperature range 45–100 °C under 20–60 atm of a CO+H 2 1:1 mixture and the reaction was generally stopped after 6 h. An almost quantitative conversion of styrene could be obtained under 50–60 atm and 75 °C in 6 h. The chemioselectivity of the reaction is satisfactory; the branched isomer aldehyde predominates in all experiments and its amount increases upon reducing the reaction temperature; at 40 atm the regioselectivity, expressed by the B/L ratio, improves from about 2.3 to 18 operating at 100 and at 45 °C. The most significant result emerges by comparison of the catalytic activity of complexes 1, [Rh(CO) 2Cl 2]AsPh 4 and 6 which shows that the ionic heterobimetallic RuRh complex 6 is much more active than the mononuclear complexes [Ru(Ph 2PPy) 3Cl]Cl and [Rh(CO) 2Cl 2]AsPh 4. This was explained by a cooperative effect between the anionic rhodium and cationic ruthenium species in complex 6. Compound 7, as a precatalyst, showed only negligible activity.

Reactions of the hexanuclear mixed-metal cluster [Ru5RhC(CO)14(η5-C5Me5)] and the synthesis, characterisation and structural analysis of the pentanuclear derivative [Ru4RhC(CO)12(η5-C5Me5)

Treatment of the hexanuclear cluster [Ru5RhC(CO)14(η5-C5Me5)]1 with 80 atmospheres of CO under 80 °C resulted in a series of decapping reactions yielding the complexes, [Ru3(CO)12], [Ru5C(CO)15] and a new green compound [Ru4RhC(CO)12(η5-C5Me5)]2. Cluster 2 crystallises in the monoclinic space group P21/n with a= 19.180(3), b= 13.940(3) and c= 10.728(2)A, β= 97.157(2)°. The five metal atoms adopt a square-based pyramidal metal framework [Ru–Ru 2.776(1)–2.873(1), Ru–Rh 2.798(1)–2.881 (1)A]. The octahedral cluster [Ru5RhC(CO)14(η5-C5Me5)]1 reacted at room temperature with a methanolic base to yield the methoxide adduct [Ru5RhC(CO)13(CO2Me)(η5-C5Me5)]–3 which on acidification immediately regenerated the parent compound. On prolonged stirring, cluster 1 reacted irreversibly with the methanolic base to form the salt [N(PPh3)2]2[Ru5RhC(CO)13(η5-C5Me5)]4.

Synthesis of the mixed-metal clusters [Ru5RhC(CO)14(cod)Y][Y = H, Au(PEt3) or Au(PPh3); cod = cycloocta-1,5-diene]; reactions of [Ru5RhC(CO)14(cod){Au(PR3)}](R = Ph or Et) and crystal structure of [Ru5RhC(CO)14(cod){µ3-Au(PPh3)}

Treatment of the pentaruthenium salt [N(PPh3)2]2[Ru5C(CO)14] with an excess of [Rh(Cod)2][SbF6](cod = cycloocta-1,5-diene) yielded the monoanion [Ru5RhC(CO)14(cod)]– which has been isolated as its [N(PPh3)2]+ salt 1. Reaction of the monoanion with HBF4·Et2O gave the hydrido derivative [Ru5RhH(C)(CO)14(cod)]2. Compound 1 reacted with the gold salts [Au(PPh3)]Cl and [Au(PEt3)]Cl, respectively, to yield the cluster compounds [Ru5RhC(CO)14(cod){Au(PPh3)}]3 and [Ru5RhC(CO)14(cod){Au(PEt3)}]4. Compound 3 crystallises in the triclinic space group P(no. 2) with a= 15.993(3), b= 9.728(2), c= 13.900(3)A, α= 90.29(2), β= 99.97(2), γ= 88.36(2)°. The metal core geometry consists of a central Ru5Rh octahedron with one Ru3 face capped by a µ3-Au(PPh3) fragment [Ru–Ru 2.787(1)–3.093(1); Ru–Rh 2.892(1)–2.952(1); Ru–Au 2.735(1)–3.082(1)A]. The reactions of 3 and 4 with norbornadiene, PPh3 and P(OMe)3 are reported.

Dissolution of the simulated fission-produced MoRuRhPd alloys in boiling nitric acid solution

The dissolution behavior of three simulated fission-produced noble metal alloy powders, i.e. Mo 0.40Ru 0.40Rh 0.10Pd 0.10 alloy with two particle sizes of 1.8 and 7.1 μm and Mo 0.20Ru 0.60Rh 0.10Pd 0.10 alloy with 3.8 μm particle size, was investigated from the time-dependence of the dissolution fraction of each component of the alloy in 3M boiling nitric acid solution. The dissolution of each component of the alloy obeyed a linear law. Although both the dissolution fraction and the dissolution rate of each component in the three alloys were different from each other, the dissolution rate constants of Ru, Rh and Pd except Mo in each alloy calculated using Jander's spherical sample model for the surface dissolution reaction were nearly the same. By comparing the present result with those reported previously, it is concluded that nearly equal dissolution rate constants were obtained for the alloys with the same (or similar) composition but the different particle size, showing the validity of the dissolution model. The total dissolution rate constants of the three MoRuRhPd alloy powders in 3M nitric acid solution determined in this study were about two orders of magnitude lower than those of MoRuRhPd alloy blocks in 7M nitric acid solution reported previously.

Catalytic wet-oxidation of human wastes produced in space: The effects of temperature elevation

The filtrate of non-catalytical wet-oxidized sewage sludge was wet-oxidized again at 290 °C and 300 °C with a RuRh catalyst. At each temperature, repeated batch tests were carried out. Both oxidation and denitrification efficiency of organic matter in the raw material were studied. In the 16 times batch tests at 300 °C, high and stable oxidation occurred. 98.0% of organic carbon in the raw material was oxidized and 98.3% of organic nitrogen was denitrified. At 290 °C, though high and stable denitrification occurred, oxidation did not occur highly and stably. A catalytic wet-oxidation system studied at 300 °C will be useful as a waste management system for a human life support system, where almost all food is resupplied from the earth. This system can prevent organic waste accumulation in the life support system.

Synthesis of pentanuclear clusters derived from [Ru3RhH2(CO)10(PPh3)(µ-COMe)]. Crystal structures of [Ru3Rh2H2(CO)12(PPh3)2] and [Ru3RhAuH(CO)10(PPh3)2-(µ3-COMe)

Reaction of [Ru3RhH2(CO)10(PPh3)(η-COMe)]2 with K[BHBus3] and then [Rh(CO)3(PPh3)2][PF6] afforded [Ru3Rh2H2(CO)12(PPh3)2]3 in 29% yield. A single-crystal X-ray diffraction characterisation of compound 3 was carried out: monoclinic, space group C2/c(no. 15), a= 19.409(4), b= 9.944(6), c= 26.153(4)A, β= 103.35(2)°, Z= 4 and R= 0.033. A trigonal-bipyramidal cluster framework of C2 symmetry was established, with an equatorial Ru3 plane, and apical Rh(CO)(PPh3) units. The hydride ligands cap two triangular faces. Using [Au(PPh3)Cl] as an alternative electrophile, [Ru3RhAuH(CO)10(PPh3)2(µ3-COMe)]4 and [Ru3RhAuH2(CO)11(PPh3)2]5 were formed in 5 and 19% yields, respectively. Complex 4 was characterised by X-ray diffraction: triclinic, space group P(no. 2), a= 11.361(3), b= 13.745(4), c= 17.124(3)A, α= 74.15(2), β= 74.59(2), γ= 73.02(2)°, Z= 2 and R= 0.037. This cluster also showed a trigonal-bipyramidal framework, with an equatorial Ru2Rh plane and capping AuPPh3 and Ru(CO)2 units. There are three bridging ligands: the COMe ligand bridges the Ru3 face, one CO bridges a Rh–Ru(apical) bond, and the hydride a Ru2Rh face. Both these clusters are 72-electron species.

Coordination compounds of 2-mercapto-1-methylimidazole with platinum(II), palladium(II), rhodium(III) and ruthenium(III)

Complexes of 2-mercapto-1-methylimidazole (TMZ) with PtII, PdII, RhIII and RuIII of the general formulae Pt(TMZ)2Cl2, Pd(TMZ)4Cl2. Rh(TMZ)Cl3 and Ru(TMZ)Cl3 have been obtained. The thermal stabilities of the compounds were estimated by derivatographic measurements and the electron-donating atom of the measurements and the electron-donating atom of the ligand was identified from the i.r. absorbtion spectra. Lattice constants for the PtII and PdII complexes were estimated from their x-ray powder diffraction patterns.

Structural trends in phosphine-substituted [RuCoxRh3–xH(CO)12](x= 0–3) clusters. Crystal structures of [RuCo3H(CO)11(PR3)](PR3= PMe3or PMe2Ph), [RuCo2RhH(CO)11(PMe2Ph)], [RuCoxRh3–xH(CO)10(PPh3)2](x= 1–2), and [RuRh3H(CO)11(PR3)](PR3= PMe3or PMe2Ph)

The crystal structures of [RuCo3H(CO)11(PMe3)], [RuCo3H(CO)11(PMe2Ph)], [RuCo2RhH(CO)11(PMe2Ph)], [RuCo1.75Rh1.25H(CO)10(PPh3)2], [RuCoRh2H(CO)10(PPh3)2], [RuRh3H(CO)11(PMe3)], and [RuRh3H(CO)11(PMe2Ph)] show [Rh4(CO)12]-like ligand arrangements with phosphines on basal rhodium or cobalt atoms. The phosphines are axially co-ordinated except in the last two compounds, where equatorial co-ordination is found. Hydrides bridge Ru–Rh edges in [RuRh3H(CO)11(PR3)](PR3= PMe3 or PMe2Ph) and basal M3 faces in the other compounds. Geometric parameters are discussed with respect to the metal combination or ligand site.

Synthesis and characterization of Ru(III), Rh(III), Pt(IV) and Ir(III) thiosemicarbazone complexes

Ru(III), Rh(III), Pt(IV) and Ir(III) complexes of 2-furfural thiosemicarbazone as ligand have been synthesised. These complexes have the composition [M(ligand)2X2]X (M = Ru(III) Rh(III) and Ir(III) X = Cl and Br) and [Pt(ligand)2 X2] X2 (X = Cl, Br and 1/2SO4). The deprotonated ligand forms the complexes of the formulae M(ligand-H)3 and Pt(ligand-H)3Cl. All these complexes have been characterized by elemental analysis, magnetic measurements, electronic and infrared spectral studies. All the complexes are six-coordinate octahedral.

Distribution of fission products in dust samples from the region of Thessaloniki, Greece, after the Chernobyl nuclear accident.

The distribution of the fission products (95)Zr, (95)Nb, (103)Ru, (106)Ru (determined through (106)Rh), (125)Sb, (129m)Te, (134)Cs, (137)Cs, (140)Ba, (140)La, (141)Ce and (144)Ce has been determined in dust samples from the region of Thessaloniki, Greece, after the nuclear accident at Chernobyl. The samples studied also included (110m)Ag, not belonging to the products of (235)U fission. Samples showing higher concentrations of radionuclides also show a higher content in clay minerals, whereas samples having low concentrations of radionuclides usually contain large amounts of quartz and feldspars. Desorption and leaching experiments using solutions of chlorides of sodium, potassium, calcium and magnesium (0.5 N), as well as distilled and tap water, were also performed. Sodium and potassium chloride solutions were found to be efficient in desorbing and/or leaching of caesium and ruthenium isotopes to an extent of about 30%.

Mobility of the dppm ligand in dinuclear RuRh complexes: formation of trinuclear RuRh 2 and RuRhCu derivatives, and X-ray structure of a new heterobimetallic hydrido-bridged complex

Protonation of RuRhH 2Cl(COD)(dppm) 2 ( 1) (COD = 1,5 cyclooctadiene, dppm = bisdiphenylphosphinomethane) with HBF 4 · Et 2O gives [RuRhHCl(COD)-(dppm) 2]BF 4 ( 2), which has been shown to contain two chelating dppm ligands on ruthenium and a bridging hydride (RuH 2.08(7) Å; RhH 1.64(8) Å). Complex 2 reacts with CO to give [RuRhHCl(CO) 3(dppm) 2]BF 4 ( 3) containing two bridging dppm groups. Reaction of 1 with 0.5 molar equivalents of [RhCl(COD)] 2 at 80°C affords the trinuclear RuRh 2H 2Cl(PhPCH 2PPh 2)(COD) 2(dppm) ( 4) in low yield (25%), and that with CuCl at room temperature gives RuRhCuH 2Cl 2 (COD)(dppm) 2 ( 5) in high yield. Complex 5 is not very stable in solution and is converted into RuCuH 2Cl(dppm) 2 ( 6), a typical adduct between a Lewis acid and a hydride complex, which can be more easily obtained from RuH 2(dppm) 2 and CuCl in toluene at 80°C.

The synthesis, structural and spectroscopic studies of [Ru2Rh2H2(CO)12

The synthesis of [Ru2Rh2H2(CO)12] is reported, together with X-ray structural and multinuclear, variable-temperature n.m.r. studies. The structure, both in the solid state and at low temperature in solution, is related to that of [Rh4(CO)12] with one basal rhodium and the apical rhodium atoms being replaced by ruthenium atoms; the hydrogen atoms are both bonded to the apical ruthenium and bridge Ru–Ru and Ru–Rh edges of the Ru2Rh2 tetrahedron. At higher temperatures, both hydrogen and carbonyl fluxionality is observed.

Reversible syntheses of mono-(cyclopentadienyl)rhodium-tri-ruthenium cluster complexes and (η-C 5Me 5) 2Rh 2Ru 2(CO) 7; crystal and molecular structures of CpRhRu 3{μ-H} 2{μ-CO}(CO) 9, Cp = η-C 5H 5 or η-C 5Me 5 and (η-C 5Me 5)Rh{μ-H} 2Ru 3{μ-H} 2(CO) 9

The mixed metal complexes CpRhRu 3{μ-H} 2{μ-CO}(CO) 9, ( 3a: Cp = η-C 5H 5; 3b: Cp = η-C 5Me 5) 4b: (η-C 5Me 5)RhRu 3{μ-H} 4(CO) 9, 5: (η-C 5Me 5) 2Rh 2Ru 2(CO) 7) are formed when H 2 is bubbled through solutions of Ru 3(CO) 12 and the respective CpRh(CO) 2 at 70–90°C. These are easily disrupted at 25°C back into the starting materials under an atmosphere of CO. Using 13CO, the starting materials are obtained with complete 13CO exchange. While CpRh(CO) 2 undergoes exchange at 25°C with 13CO at atmospheric pressure, Ru 3(CO) 12 does not, nor does it exchange in the presence of simply an added amount of CpRh(CO) 2. Attachment of the CpRh moiety to the Ru 3 skeleton as in the products obtained in this work thus leads, under 13CO, to the completely enriched starting materials Ru 3( 13CO) 12 and CpRh( 13CO) 2. Structures of three new products have been determined using a Picker (FACS-1) four circle automated diffractometer and graphite-monochromatized Mo- K α radiation. For 3a, 3831 unique reflections with I > 3σ( I) were used in the refinement; final discrepancy indices, R = 0.030 and R w = 0.050. Complex 3a crystallizes in the monoclinic space group P2 1/ n; cell dimensions a 8.1856(5), b 15.0706(10), c 16.3013(12) Å, and β 91.033(1)°; calculated density 2.49 g cm −3. For 3b, 4801 unique reflections with I > 3σ( I) were used in the refinement; final discrepancy indices, R = 0.026 and R w = 0.042. Complex 3b crystallizes in the monoclinic space group P2 1/ n in a cell having the dimensions of a 8.7580(5), b 14.5578(8), c 19.829(1) Å, and β 97.591(2)°; calculated density 2.18 g cm −3. For 4b, 6756 unique reflections with I > 3σ( I) were used in the refinement; final discrepancy indices, R = 0.030 and R w = 0.040. Complex 4b crystallizes in the monoclinic space group P2 1/ a; cell dimensions a 17.470(1), b 18.451(1), c 17.200(1) Å, and β 114.684(1)°; calculated density 2.10 g cm −3. Metal atoms in all three structures were located by direct methods (MULTAN80). All other nonhydrogen atoms were then located by difference maps. Hydrogen atoms bridging various edges of the clusters were located after all hydrogen atoms in the η-C 5H 5 (= Cp) or η-C 5(CH 3) 5 (= Cp★) groups were refined isotropically in calculated positions. Each of the crystals studied consists of discrete molecules of the complexes, each with a triangle of ruthenium atoms capped by a CpRh or Cp★Rh group. Isomeric structures are observed for 3a and 3b. In the former, a CO group is found bridging between one Ru atom and the Rh atom while one each of two cluster-bound hydrogen atoms bridge two separate edges of the Ru 3 triangle. In 3b, both a CO group and one of the cluster-bound hydrogen atoms are found bridging between Rh and two separate Ru atoms of the Ru 3 triangle. The remaining cluster-bonded hydrogen atom is found bridging one edge of the Ru 3 triangle. In 4b, two of the cluster-bound hydrogen atoms are found (one each) on two edges of the Ru 3 triangle. The other two are found bridging each of two of the RuRh bonds. The metal—metal separations in the three structures are summarized as follows. Unbridged RuRu and RhRu fall in the ranges 2.765(1) to 2.813(1) Å and 2.707(1) to 2.752(1) Å, respectively; the Rh-μ-(CO)-Ru separations are 2.727(1) (in 3a) and 2.7515(1) (in 3b). Ru-μ-(H)-Ru separations fall in the range 2.870(1) to 2.938(1) Å while Rh-μ-(H)-Ru fall in the range 2.871(1) to 2.9169(1) Å.

Synthesis and X-ray structural studies on the cluster compounds [RuRh3(µ3-CO)2(CO)3(η-C5Me5)3] and [RuRh2(µ-CO)(µ3-CO)(CO)2(η4-C8H10)(η-C5Me5)2

The compounds [Ru(η6-C8H10)(cod)](C8H10= cycle-octa-1,3,5-triene, cod = cycle-octa-1,5-diene) and [Rh(CO)2(η-C5Me5)] react in toluene at 60 °C to give the cluster compounds [RuRh3(µ3-CO)2(CO)3(η-C5Me5)3](1) and [RuRh2(µ-CO)(µ3-CO)(CO)2(η4-C8H10)(η-C5Me5)2](2). The structures of these compounds were established by single-crystal X-ray diffraction studies. Compound (1) has a distorted tetrahedral RuRh3 metal atom core [Rh–Rh 2.684(1)–2.739(1), Ru–Rh 2.620(1)–2.715(1)A]. The rhodium atoms are each ligated by an η-C5Me5 group, the ruthenium atom is terminally bonded to three carbonyl groups, while the remaining two CO ligands triply and asymmetrically bridge the Rh3 face and one RuRh2 face of the metal polyhedron. In compound (2) the C8H10 ligand attached to the ruthenium is bicyclo[4.2.0]octa-2,4-diene. The molecule comprises a metal atom triangle [Ru–Rh 2.766(1) and 2.815(1), Rh–Rh 2.672(1)A] and an η-C5Me5 group is co-ordinated to each rhodium atom. The four CO ligands show a remarkable variety of bonding modes. One carbonyl group attached to the ruthenium atom is essentially terminally bound to that centre [Ru–C–O 167.5(4)°], while a second carbonyl group attached to the ruthenium semi-bridges an edge of the metal triangle [Ru–C–O 158.1(4)°; Ru–CO 1.930(4), Rh ⋯ CO 2.412(5)A]. The Rh–Rh vector is symmetrically bridged by another CO ligand [Rh–C–O 137.3(3) and 138.2(3)°, Rh–CO 1.989(3) and 2.000(4)A]. The remaining carbonyl group asymmetrically bridges the face of the triangle [Ru–CO 2.247(4), Rh–CO 2.038(4) and 2.069(4)A]. Spectroscopic studies (i.r. and n.m.r.) on (1) and (2) are reported. Both compounds show site exchange of CO groups in solution (13C-{lH} n.m.r.) but the process in (1) is limited to the Ru(CO)3 group, with the dynamic behaviour persisting at –80 °C. With (2), at room temperature, all four CO ligands exchange, but at –80 °C separate signals for the µ-CO and µ3-CO groups are seen, although only one resonance is observed for the two CO groups attached to the ruthenium atom. These and other data are discussed, and a mechanism proposed to account for the formation of (1) and (2).

Separation and determination of phenylhydrazine-N-dithiocarbamates of ruthenium(III), rhodium(III) and palladium(II) from other Group VIII metals using thin-layer chromatography and visible spectrophotometry

Phenylhydrazine-N-dithiocarbamate forms coloured complexes with Ru(III) Rh(III), Pd(II), Fe(III), Ce(III), Ni(II), Ir(III) and Pt(IV). The dithiocarbamates of Ru, Rh, lr and Pd are soluble in acetone whereas those of Fe, Co, Ni and Pt are insoluble. The separation of the phenylhydrazine-N-dithiocarbamates of Ru(III), Rh(III) and Pd(II) from other Group VIII metals and their determination has been carried out using TLC and visible spectrophotometry. Ru, Rh and Pd dithiocarbamates can be resolved successfully in chloroform, benzene, ethyl acetate-carbon tetrachloride (1 + 4) and acetonitrile-carbon tetrachloride (1 + 4). The coloured spots of the dithiocarbamates are visible in daylight and are the same in the different mobile phases.

The interaction of platinum metals at 1400 °C

Abstract A combination of physical and chemical analysis methods (microstructural, X-ray phase and electron probe analysis techniques) and measurements of the hardness and microhardness were used to investigate ternary and quaternary PtRhPd(Ir), PdIrPt(Rh), RhRuPd(Ir), PtRuRhPd(Ir) and PtPdRhIr alloys annealed at 1400 °C. The results of the investigations are used to plot phase equilibrium diagrams for these systems at 1400 °C. Changes in the hardness, microhardness and lattice cell volumes in the alloy phases were studied along some sections. The directions of the tie-lines in the two-phase regions were calculated.

The constitution of the RuRh system

Abstract The constitution of the RuRh system was investigated between 900 and 2300 °C using metallography, X-ray diffraction, differential thermal analysis, electron microprobe analysis and microhardness measurements. The system is of the simple peritectic type with a peritectic temperature of 2090 °C and a peritectic composition of about 70 at.% Rh. Intermetallic phases were not observed. The maximum solubility of rhodium in ruthenium is 60.0 at.%, and that of ruthenium in rhodium is 34.5 at.%. The lattice parameter c and the c a ratio increase with increasing rhodium content in the h.c.p. ϵ-Ru(Rh) solid solution, whereas the lattice parameter a in the f.c.c. α-Rh(Ru) solid solution is only slightly changed. Microhardness measurements in the α-Rh(Ru) solid solution reveal a rapid increase with increasing ruthenium content; microhardness changes in the ϵ-Ru(Rh) solid solution are insignificant.