Maria P. Garcia

A new route for the synthesis of binuclear organometallic and inorganic palladium(II) complexes

Abstract A new generally applicable route for the preparation of binuclear organometallic palladium(II) complexes is described. Compounds of the general formula [Pd(μ-Cl)RL] 2 (R being C 6 F 5 or C 6 Cl 5 ; L being a neutral ligand with N, P, As, Sb or S as donor atom) have been obtained by the reaction of organometallic compounds of the PdR 2 L 2 type with PdCl 2 in acetone solution at room temperature. The reaction with PdCl 2 had also been used for the systhesis of inorganic palladium(II) derivatieves of the [PdCl 2 L] 2 type. The structure of the novel organometallic complexes is discussed.

Differentiation of red wines using an electronic nose based on surface acoustic wave devices

An electronic nose, utilizing the principle of surface acoustic waves (SAW), was used to differentiate among different wines of the same variety of grapes which come from the same cellar. The electronic nose is based on eight surface acoustic wave sensors, one is a reference sensor and the others are coated by different polymers by spray coating technique. Data analysis was performed by two pattern recognition methods; principal component analysis (PCA) and probabilistic neuronal network (PNN). The results showed that electronic nose was able to identify the tested wines.

Detection of toxic gases by a tin oxide multisensor

A tin oxide multisensor with eight sensor elements has been utilized to detect different gases that are emitted from the chemical industry. The different sensors have been prepared using the RF reactive sputtering technique. Some components of this multisensor were doped with Pt and Cr by sputtering. Each sensor has been characterized by electrical measurements for detection of atmospheric pollution (nitrogen dioxide, carbon monoxide, toluene, and propanal). The detected gases are toxic and their extreme concentrations recommended in air oscillate from 1 ppm to hundreds of ppm. Detections were carried out with a single gas or a gas mixture (two gases) in dry air at 250/spl deg/C. The sensitivity and selectivity to these gases were studied. Backpropagation neural networks and their classification results were discussed.

Synthesis and catalytic activity of heterodinuclear Ru-Ir and Ru-Rh complexes. Crystal structure of [H(CO)(PPh3)2Ru(μ-Cl)(μ-pz)Ir(TFB)] (pz = pyrazolate, TFB = tetrafluorobenzobarrelene)

Abstract Reactions of the ruthenium compounds [RuHCl(CO)(PR 3 ) n ] (R = Ph, n = 3; R = i Pr, n = 2) with pyrazole C 3 H 4 N 2 (Hpz) give the complexes [RuHCl(CO)(Hpz)(PR 3 ) 2 ]. Treatment of these complexes with a hydrogen abstractor (methoxide ion or acetylacetonate (acac)), such as [M(μ-OMe)(diolefin)] 2 (M = Ir, Rh; diolefin = cycloocta-1,5-diene (COD), tetrafluorobenzobarrelene (TFB)) or [Pd(acac)(η 3 -C 3 H 5 )] has given the heterobinuclear complexes [H(CO)(PR 3 ) 2 Ru(μ-Cl)(μ-pz)ML 2 ] (R = Ph; M = Ir or Rh, L 2 = COD or TFB; R = i Pr, M = Rh, L 2 = TFB; R = Ph, M = Pd, L 2 = C 3 H 5 ). The structure of [H(CO)(PPh 3 ) 2 Ru(μ-Cl)(μ-pz)Ir(TFB)] has been established by an X-ray diffraction study. The species is binuclear, with a pyrazolate group and a chlorine atom as bridging ligands. The intermetallic separation is 3.8907(6) A. The reduction of cyclohexanone by hydrogen transfer from isopropanol catalyzed by [H(CO)(PPh 3 ) 2 Ru(μ-Cl)(μ-pz)M(diolefin)] (M = Ir, Rh; diolefin = COD, TFB) is also reported.

Metallaborane chemistry. Part 14. Icosahedral η6-arena carbametallaboranes of iron and ruthenium; molecular structures of closo-[1-(η6-C6H5Me)-2,4-Me2-1,2,4-FeC2B9H9] and closo-[3-(η6-C6H6)-3,1,2-RuC2B9H11]

Icosahedral 2,4-dicarba-1-ferraboranes with η6-bonded benzene, toluene, o-xylene, or naphthalene ligands have been synthesised in moderate yields by reaction of [Fe(cod)(η5-C5H5)](cod = cyclo-octa-1,5-diene) with 2,3-Me2-2,3-C2B9H9 in the presence of the appropriate arene. In addition, the toluene derivative, closo-[1-(η6-C6H5Me)-2,4-Me2-1,2,4-FeC2B9H9](2), has also been obtained by treatment of the carbaborane with [Fe2(µ-η-C6Me6)(η5-C5H5)2] in toluene. Reaction of [RuCl2(η6-C6H6)2] with Tl[TlC2B9H11] affords closo-[3-(η6-C6H6)-3,1,2-RuC2B9H11](7). Complexes (2) and (7) have been characterised by single-crystal X-ray diffraction. Crystals of (2) are orthorhombic, space group Pna21, with a= 21.793(4), b= 8.6274(15), c= 8.636(3)A, and Z= 4; R= 0.0499 for 1 676 reflections. Complex (7) is also orthorhombic, space group Pnam, with a= 18.477(2), b= 9.191(4), and c= 7.704(1)A, and Z= 4; R= 0.0223 for 1 723 data. Both species have slightly distorted Icosahedral cage geometries and overall Cs molecular symmetry, space group imposed for (7). The naphthalene derivative [1-(η6-C10H8)-2,4-Me2-1,2,4-FeC2B9H9] undergoes substitution of the arene ligand by CO at 100 bar and 50 °C, to afford the complex [1,1,1-(CO)3-2,4-Me2-1,2,4 FeC2B9H9].

Synthesis of mononuclear complexes of Ru and Os and heterobimetallic M–M′(M = Ru or Os; M′= Rh, Ir, or Au) compounds with pyrazolate or imidazolate type ligands. X-Ray crystal structure of [(Ph3P)2(OC)HRu(µ-bim)Rh(cod)](bim = dianion of 2,2′-bi-imidazole, cod = cyclo-octa-1,5-diene)

The synthesis and characterization of several mono- and poly-(di-, tri-, or tetra)-nuclear compounds are reported. The mononuclear compounds are of the type [MH(CO)(HL)(PPh3)2][M = Ru or Os; [HL = Hbim (monoanion of 2,2′-bi-imidazole), Hbbzim (monoanion of 2,2′-bibenzi-imidazole)], or [RuH(pz)(CO)(Hpz)(PPh3)2][Hpz(pyrazole)]. They react with [{M′(µ-OMe)(diolefin)}2]{M′= Rh or Ir; diolefin = cyclo-octa-1,5-diene (cod) or tetrafluorobenzobarrelene (tetrafluorobenzo-[5,6]bicyclo[2.2.2]octa-2,5,7-triene)(tfbb)}, giving the heterodinuclear complexes [(Ph3P)2(OC)HMLM′(diolefin)]. In some of these compounds the diolefin can easily be displaced by carbon monoxide yielding [(Ph3P)2(OC)HRuL2M′(CO)2][L2= bbzim, M′= Rh; L2=(pz)2, M′= Rh or Ir]. The structure of [(Ph3P)2(OC)HRu(µ-bim)Rh(cod)] was established by X-Ray crystallography: the crystals are monoclinic, space group P21/n, a= 16.209 1 (7), b= 14.437 1 (5), c= 18.960(1)A, β= 93.700(4)°, and Z= 4. The molecule is binuclear with a 2,2′-bi-imidazolate ligand bridging, as a tetradentate bichelating group, two different metallic centres, a square-planar rhodium(I) and a slightly distorted octahedral ruthenium(II). In this molecule, the rhodium co-ordination sphere, the bridging anion, and the carbonyl and hydride ligands are planar. The Ru–N bond distances are markedly asymmetric [2.283(5) and 2.180(5)A, to N(1) and N(2)] reflecting their different trans groups: a hydride and a carbonyl. The compound [RuH(CO)(Hbim)(PPh3)2] reacts with [Au(PPh3)]BF4 in different proportions affording heteropolynuclear Ru(µ-H)Au complexes of formula [(Ph3P)2(OC)HRu(µ-bim){Au(PPh3)}2]BF4, [(Ph3P)Au(µ-H)(Ph3P)2(OC)Ru(µ-bim){Au(PPh3)2][BF4]2, and [(Ph3P)Au(µ-H)(Ph3P)2(OC)Ru(µ-Hbim){Au(PPh3)}][BF4]2.

Mononuclear rhodium(I) complexes of 4-Amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole. Crystal structure of [Rh(CO)2(NH2bpt)]ClO4

Abstract Reaction of 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole (NH2bpt) or its potassium salt (KNHbpt) with several rhodium(I) compounds, produces new neutral and cationic complexes of Rh(I). One of the complexes [Rh(CO)2(NH2bpt)]ClO4 has been characterized by single-crystal X-ray diffraction. The crystals are monoclinic, space group P21/n, with a = 17.6130(6), b = 11.3072(2), c = 9.0013(2) A, β = 101.536(2)° and Z = 4. The structure has been refined to R = 0.049.

Evidence for enhancement of catalysis by a second metal in heterobinuclear complexes: X-ray structure of [H(CO)(PPh3)2Ru(bim)Rh(cod)](bim = 2,2′-bi-imidazolato, cod = cyclo-octa-1,5-diene)

The binuclear complexes [H(CO)(PPh3)2Ru(bim)M(cod)](M = Rh or Ir, cod = cyclo-octa-1,5-diene) are more active as catalysts for the reduction of cyclohexanone, styrene, benzylideneacetophenone, and cyclohexene than the mononuclear parent (ruthenium, rhodium, or iridium) compounds.

Rhodium(I) complexes with the 2,2′-bipyrimidine ligand

Abstract Mono- and dinuclear rhodium(I) complexes of formulae [Rh(L2)(bipym)]+ and [{Rh(L2)}2(μ-bipym)]2+ [L2 = diolefin or (CO)2] have been prepared and their catalytic activity in hydrogen-transfer reactions explored. The heterodinuclear [Cl2Pd(μ-bipym)Rh(tfb)]ClO4 complex was obtained by reacting [Rh(tfb)(bipym)]+ with [PdCl2(cod)] or alternatively from [Rh(tfb)(acetone)x]+ with [PdCl2(bipym)]. Ion-pair complexes of formulae [Rh(diolefin)(bipym)]+ [RhCl2(diolefin)]− (diolefin = cod, nbd or tfb) were prepared by adding bipym to acetone suspensions of [RhCl(diolefin)]2.

Synthesis of ruthenium-palladium and ruthenium-rhodium complexes linked by pyrazolate groups and chlorine atoms. Crystal structure of [(p-cymene)ClRu(μ-Cl)(μ-pz)Pd(C8H11)]

Abstract The preparation of new heterobinuclear compounds of formula [(p-cymene)RuX2(Pz)ML2] (M = Pd, X = Cl, L2 = C3H5, C4H7 or C8H11; Pz = pz 1 ; M = Rh, X = Cl or I, L2 = 5,6,7,8-tetrafluoro-1,4-dihydro-1,4-ethenonaphthalene, tfb, or bicyclo[2.2.1]heptadiene, nbd; Pz = pz or Mepz) is reported. One of the complexes, [(p-cymene)ClRu(μ-Cl)(μ-pz)Pd(C8H11)], has been characterized by single-crystal X-ray diffraction. The crystals are monoclinic, space group P21/c, with a 14.0044(10), b 14.9641(10), c 11.0456(5) A, β 103.191(5)° and Z = 4. The structure has been refined to R = 0.064 for the 2850 observed reflexions with I ρ 3σ(I). The coordination of the Pd atom to the C8H11 ring system involves only three C atoms constituting a η3-allyl group, at 2.147(17), 2.101(15) and 2.119(17) A from the Pd atom. The Ru-Pd distance is 3.516(1) A, the two atoms being bridged by a chlorine atom and a pyrazolate group; the other chlorine atom is terminal.