Interaction Of Ru Research Articles

Species variations in RU 24969 interactions with non-5-HT 1A binding sites

The interaction of RU 24969 with [ 3H]5-HT) binding to non-5-HT 1A binding sites was analyzed in nine species. Non-5-HT 1A binding was defined as specific [ 3H]5-HT binding observed in the presence of 100 nM 8-OH-DPAT. Computer-assisted iterative curve fitting of RU 24969 competition studies indicate that RU 24969 distinguishes two distinct components of non-5-HT 1A sites in rat and mouse brain. These two binding components display apparent K i values of 0.33–0.39 and 66–130 nM for RU 24969. By contrast, RU 24969 competition for non-5-HT 1A binding in guinea-pig, cow, human, dog, chicken, turtle and frog brain membranes is consistent with a homogeneous population of [ 3H]5-HT binding sites. This population of sites displays apparent K i values of 23–130 nM for RU 24969 and appear to be analogous to the low affinity component of non-5-HT 1A sites identified in rat and mouse.

Reactions of hydrido(cycloocta-1,5-diene)tris(phosphine)ruthenuim(II) cations with 1,3-dienes: Formation of agostic η 3-enyl species [Ru(η 3-enyl)L 3] +

Treatment of either the hydrido-diene complexes [RuH(cod)L 3][PF 6] (cod = cycloocta-1,5-diene, L = PMe 3, PMe 2Ph, P(OMe) 2Ph, P(OMe)Ph 2) or the isomeric cyclooctenyl species [Ru(η 3-C 8H 13)L 3][PF 6] with 1,3-dienes gives the corresponding η 3-enyl cations [Ru(η 3-hepteny)L 3] +, [R(η 3-hexeny)L 3] + and [R(η 3-butenyl)(PMe 2Ph) 3] +. The products contain an aliphatic CH ⋯ Ru interaction and exhibit four distinct fluxional processes as revealed by variable temperature NMR studies: mutual exchange of the phosphorus donor ligands; a 1,2-metal migration around the endo face of the carbocyclic ring; an exchange involving CH interaction at the metal, and in the case of the butenyl complex, methyl group rotation. Whereas the first two processes are of relatively high energy and can be frozen out at low temperatures, the remaining processes are still rapid at the lowest temperature investigated (183 K), except for the complex [Ru(η 3-cycloheptenyl){P(OMe) 2Ph} 3] + which gave a slow-exchange 1H NMR spectrum at 500 MHz.

Cytochrome b reduction by hexaammineruthenium in mitochondria and submitochondrial particles : Evidence for heme b-562 localization at the M-side of the mitochondrial membrane

In the presence of ascorbate, hexaamineruthenium mediates rapid reduction of cytochrome b-562 in submitochondrial particles but not in mitochondria. The reaction is obsreved in the combined presence of antimycin (or funiculosin) and myxothiazol, which implies direct interaction of Ru(NH 3) 2+ 6 with b cytochrome(s). We assume that contrary to previous conclusions (Case and Leigh (1976) Biochem. J., 160, 769-783) redox centre of at least one of the oxidized cytochromes b, most probably of b-562, is exposed to the M-aqueous phase.

X-Ray and neutron diffraction studies on [Ru4(CO)8(µ-H)4{P(OCH3)3}4] at 293 and 20 K : characterisation of the vibrational behaviour of two-co-ordinate hydrogen atoms

X-Ray and neutron diffraction studies on the complex [Ru4(CO)8H4{P(OCH3)3}4] have been carried out at 293 and 20 K respectively. At room temperature the structure is monoclinic, space group P21/c with cell parameters a= 15.700(4), b= 11.775(3), c= 21.331(5)Å, β= 100.49(4)°, and Z= 4. At 20 K the structure is triclinic, space group P with a= 15.371(3), b= 11.508(2), c= 21.079(3)Å, α= 90.07(1), β= 100.09(1), γ= 92.09(2)°, and Z= 4. The X-ray determination shows the molecular structure to consist of distorted tetrahedral Ru4 units substituted so that each ruthenium atom is bound to two terminal carbonyl ligands, one trimethyl phosphite ligand, and two hydride ligands. Despite positional disorder affecting four methoxy groups, the µ-hydride ligands spanning four edges of the Ru4 tetrahedron were located and refined. At low temperature the structure is ordered with two molecules per asymmetric unit, and the neutron analysis provides precise characterization of the molecular structure. All the Ru–H–Ru bridges are symmetrical with mean Ru–H = 1.773(2)Å and show closed three-centre two-electron bonding. Final agreement indices are R(F)= 0.043, R′(F)= 0.038 for 6 647 unique X-ray data, and R(F)= 0.048, R′(F)= 0.038 for 8 601 unique neutron data. Analysis of the vibrational behaviour of the hydride hydrogen atoms as determined in the neutron analysis indicates that this motion is consistent with these hydrogens residing in a single-minimum potential well provided by symmetric three-centre, two-electron Ru–H–Ru interactions.

Surface characterization of the [formula omitted] system : II. Structure and reactivity of the surface carbonylic complexes

The structure of the anchored carbonylic complexes (Ru A, Ru B, and Ru C) formed by interaction of Ru 3(CO) 12 with Al 2O 3 is further investigated by 13CO 12CO isotopic substitution. All complexes contain two coupled CO oscillators per ruthenium centre and the local structure is tetrahedral (Ru A) or octahedral (Ru B and Ru C). The reactivity of these species towards simple molecules is also tested and the interconversion of the Ru B and Ru C species in reducing and oxidizing atmospheres is established. The oxidation states III, II, and 0 are proposed for Ru in the Ru A, Ru B, and Ru C species, respectively.

Zeolite support effects on CO–Ru interactions

An i.r. study of CO adsorption on a series of zeolite-supported Ru catalysts relates strong metal–support interactions to higher zeolite acidity and lower Fischer–Tropsch/methanation activity.

An infrared study of alumina- and silica-supported ruthenium cluster carbonyls

An investigation has been performed of the adsorption of Ru 3(CO) 12, α-H 4Ru 4(CO) 12, and Ru 6C(CO) 17 on γ-Al 2O 3 and SiO 2, and of the structures formed upon decomposition of the initially supported clusters. The extent of Ru 3(CO) 12 adsorption on γ-Al 2O 3 strongly depends on the temperature at which the support had been dehydroxylated. Infrared spectra of alumina-supported Ru 3(CO) 12 suggest that the cluster is adsorbed as a result of interactions between the carbonyl ligands and hydroxyl groups and Lewis acid sites present on the support surface. Similar interactions are proposed for alumina-supported α-H 4Ru 4(CO) 12 and Ru 6C(CO) 12. Decomposition of the supported clusters produces three surface structures, independent of the original cluster composition. The first structure is characterized by bands at 2045–2050 and 1965–1970 cm −1 and is represented by [Ru(CO) 2X 2] n . The second and third structures are characterized by bands at 2130–2140, 2060–2070, and 1990–2000 cm −1 and are represented by [Ru(CO) 3X 2] n and [Ru(CO) 4X 2] n , respectively. In each of the structures X represents an oxygen atom of the alumina lattice. The nuclearity of the surface structures, n, cannot be defined from the present studies. Complete decarbonylation of the Ru surface structures induces a stronger Ru-support interaction, which may lead to the entry of Ru ions into the support lattice and the formation of surface aluminates. The aluminates are not stable, however, and the initial three structures can be regained by heating in CO. Upon reduction of the supported clusters in H 2 at temperatures above 400 °C, Ru microcrystallites appear to be formed. These particles are not stable and the Ru is redispersed into smaller units if the sample is heated in CO above 200 °C. By contrast with γ-Al 2O 3, the interactions of Ru 2(CO) 12 with SiO 2 are very weak. As a consequence Ru microcrystallites are formed when the supported cluster is reduced in H 2 at temperatures above 400 °C.

The interaction of organic isothiocyanates with complexes of ruthenium and rhodium. Formation of Π-bound isothiocyanate, isonitrile-dithiocarbonimidato complexes and a new route to isonitrile-dioxygen complexes of rhodium.

Simple π-bound isothiocyanate complexes result from the interaction of Ru(CO) 2(PPh 3) 3 with RNCS (R  Ph, Et, Me). Both RU(CO) 2(PPh 3) 2(π-RNCS) (I) and Ru(Co) 2(PPh 3) 3 react with excess RNCS to yield the isonitrile-dithiocarbonimidato derivatives, Ru(CO) (CNR) (S 2CNR) (PPH 3) 2(II). When RhCl(PPh 3) 3 reacts with RNCS (R  Bz, c -hex, Ph, tBu, nBu, Et), a simple π-RNCS adduct may not be isolated but is a presumed intermediate in the formation of the isonitrile-dithiocarbonimidato derivatives RhCl(CNR) (S 2CNR) (PPh 3) 2(III). Methyl iodide effects alkylation at the nitrogen of the dithiocarbonimidato ligand of III to give the series of cationic complexes, [RhCl (CNR) {S 2CN(Me)R} PPh 3) 2]I (R  Bz, Ph, Et) (IV). Complex III also reacts with triphenylphosphine to give in solution trans -RhCl(CNR) (PPh 3) 2, which rapidly coordinates dioxygen to give complexes of the type. RhCl(CNR) (PPh 3) 2(O 2) (R  Ph, c -hex. tBU, nBu) (V).

Pharmacological interactions with circling behaviour induced by the piperidinyl indole derivative RU 23686.

When administered i.p. from doses of 10 mg/kg, RU 23686 [5-methoxy 3-(4-piperidinyl) 1H-indole hydrochloride], a drug with relatively weak stimulant properties, induces contralateral (C) circling behaviour in rats with a unilateral electrolytic lesion in the striatum and a more complex effect with ipsilateral (1) and/or C circling in rats with a 6-hydroxydopamine (6-OHDA) lesion in the dopamine (DA) nigro-striatal tract. Interactions of RU 23686 with pharmacological agents have been studied in order to investigate the extent to which different neurotransmitters may be implicated in the circling behaviour induced by this compound.

Structural studies in the ruthenium–dithiocarbamate system. Part II. Crystal structures of two salts of the [Ru2(dtc)5]+ cation, one containing the [Ru2Cl6]2– anion

The crystal structures of two derivatives of ruthenium di-isopropyldithiocarbamate (dtc) have been determined by X-ray diffraction: viz. (I)[Ru2(dtc)5]Cl,2.5C6H6 and (II)[Ru2(dtc)5]2[Ru2Cl6],2CHCl3,(C6H12 ?). The structures were solved by the heavy-atom method and refined by least squares to R 0·084 [(I) 5 079 reflections] and 0.12 [(II) 4 714 reflections]. Crystals of both are monoclinic, space groups P2l/a(I), P21n(II); for (I)a= 27.13(1), b= 17.25(2), c= 14.53(3)A, β= 97.82(4)°, Z= 4; for (II)a= 33.83(1), b= 12.527(2), c= 15.825(2)A, β= 95.72(2)°, Z= 2. Within the [Ru2(dtc)5]+ cation, a strong Ru ⋯ Ru interaction is found, the geometry of the bridging ligands being greatly compressed with a short Ru ⋯ Ru distance [2·789(4)A]. The bridging dithiocarbamate groups are also unusual: the pπ orbital of one of the sulphur atoms is utilized for bonding so that there is an unusual disparity in the two C ⋯ S distances, the longer of which approximates to the single-bond value. (II) contains the novel [Ru2Cl6]2– centrosymmetric anion; the ruthenium atoms are pseudo-tetrahedral.