31 results on '"Burgun, Alexandre"'
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2. Some reactions of azides with diynyl-bis(phosphine)ruthenium-cyclopentadienyl complexes
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Bruce, Michael I., Burgun, Alexandre, George, Jonathan, Nicholson, Brian K., Parker, Christian R., Skelton, Brian W., Scoleri, Nancy, Sumby, Christopher J., and Zaitseva, Natasha N.
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- 2015
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3. Some cyclic ligands obtained from reactions of polycyanocarbon–metal complexes
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Bruce, Michael I., Burgun, Alexandre, Jevric, Martyn, Morris, Jonathan C., Nicholson, Brian K., Parker, Christian R., Scoleri, Nancy, Skelton, Brian W., and Zaitseva, Natasha N.
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- 2014
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4. Capturing snapshots of post-synthetic metallation chemistry in metal–organic frameworks
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Bloch, Witold M., Burgun, Alexandre, Coghlan, Campbell J., Lee, Richmond, Coote, Michelle L., Doonan, Christian J., and Sumby, Christopher J.
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- 2014
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5. An Ru-Substituted Tris(ethynyl)methyl Cation: Synthesis, Properties, and Structure of [{Cp(dppe)Ru(C≡C)}3C]PF6·C6H6*.
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Bruce, Michael I., Burgun, Alexandre, Nicholson, Brian K., and Zaitseva, Natasha N.
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CATIONS , *PYRAZOLYL compounds , *ETHANES , *RESONANCE , *BENZENE , *OXIDATION - Abstract
The dark blue complex [{Cp(dppe)Ru(C≡C)}3C]PF6 1 (Cp = cyclopentadienyl, dppe = 1,2-bis(diphenylphosphino)ethane) was obtained in 46 % yield by treatment of Ru(C≡CH)(dppe)Cp with CuCl/TMEDA (tetramethylethanediamine), followed by KOH and [NH4]PF6 in acetone; it was accompanied by known complexes {Cp(dppe)Ru}C≡CC≡C{Ru(dppe)Cp} 2 (22 %) and yellow [1,3-{Cp(dppe)Ru}2C4H3]PF6 3 (2.6 %). The structure of the cationic fragment of 1 in its benzene solvate consists of a central planar C attached to three C≡CRu(dppe)Cp fragments. The cation of 3 consists of a cyclobuten-1,3-diyl group bearing two Ru(dppe)Cp groups. The 13C NMR resonance of the central C in 1 is found at δ 66.11. The cyclic voltammogram of 1 contains three irreversible oxidation waves at +0.87, +0.79, and +0.25 V, together with a reversible reduction wave at −1.38 V (versus FeCp2/[FeCp2]+). The dark blue complex [{Cp(dppe)Ru(C≡C)}3C]PF6 1 was obtained in 46 % yield by treatment of Ru(C≡CH)(dppe)Cp with CuCl/TMEDA, followed by KOH and [NH4]PF6 in acetone; it was accompanied by known complexes {Cp(dppe)Ru}C≡CC≡C{Ru(dppe)Cp} 2 (22 %) and yellow [1,3-{Cp(dppe)Ru}2C4H3]PF6 3 (2.6 %). [ABSTRACT FROM AUTHOR]
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- 2020
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6. An Ru-Substituted Tris(ethynyl)methyl Cation: Synthesis, Properties, and Structure of [{Cp(dppe)Ru(C≡C)}3C]PF6·C6H6*.
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Bruce, Michael I., Burgun, Alexandre, Nicholson, Brian K., and Zaitseva, Natasha N.
- Abstract
The dark blue complex [{Cp(dppe)Ru(C≡C)}
3 C]PF6 1 (Cp = cyclopentadienyl, dppe = 1,2-bis(diphenylphosphino)ethane) was obtained in 46 % yield by treatment of Ru(C≡CH)(dppe)Cp with CuCl/TMEDA (tetramethylethanediamine), followed by KOH and [NH4 ]PF6 in acetone; it was accompanied by known complexes {Cp(dppe)Ru}C≡CC≡C{Ru(dppe)Cp} 2 (22 %) and yellow [1,3-{Cp(dppe)Ru}2 C4 H3 ]PF6 3 (2.6 %). The structure of the cationic fragment of 1 in its benzene solvate consists of a central planar C attached to three C≡CRu(dppe)Cp fragments. The cation of 3 consists of a cyclobuten-1,3-diyl group bearing two Ru(dppe)Cp groups. The13 C NMR resonance of the central C in 1 is found at δ 66.11. The cyclic voltammogram of 1 contains three irreversible oxidation waves at +0.87, +0.79, and +0.25 V, together with a reversible reduction wave at −1.38 V (versus FeCp2 /[FeCp2 ]+ ). The dark blue complex [{Cp(dppe)Ru(C≡C)}3 C]PF6 1 was obtained in 46 % yield by treatment of Ru(C≡CH)(dppe)Cp with CuCl/TMEDA, followed by KOH and [NH4 ]PF6 in acetone; it was accompanied by known complexes {Cp(dppe)Ru}C≡CC≡C{Ru(dppe)Cp} 2 (22 %) and yellow [1,3-{Cp(dppe)Ru}2 C4 H3 ]PF6 3 (2.6 %). [ABSTRACT FROM AUTHOR]- Published
- 2020
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7. Protecting-Group-Free Site-Selective Reactions in a Metal--Organic Framework Reaction Vessel.
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Huxley, Michael. T., Burgun, Alexandre, Ghodrati, Hanieh, Coghlan, Campbell J., Lemieux, Anthony, Champness, Neil R., Huang, David M., Doonan, Christian J., and Sumby, Christopher J.
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METAL-organic frameworks , *AZIDES , *NUCLEAR magnetic resonance spectroscopy , *ALKYLATION , *RING formation (Chemistry) - Abstract
Site-selective organic transformations are commonly required in the synthesis of complex molecules. By employing a bespoke metal-organic framework (MOF, 1⋅[Mn(CO)3N3]), in which coordinated azide anions are precisely positioned within 1D channels, we present a strategy for the site-selective transformation of dialkynes into alkyne-functionalized triazoles. As an illustration of this approach, 1,7-octadiyne-3,6-dione stoichiometrically furnishes the mono-"click" product N-methyl-4-hex-5'-ynl-1',4'-dione-1,2,3-triazole with only trace bis-triazole side-product. Stepwise insights into conversions of the MOF reaction vessel were obtained by X-ray crystallography, demonstrating that the reactive sites are "isolated" from one another. Single-crystal to single-crystal transformations of the Mn(I)-metalated material 1⋅ [Mn(CO)3(H2O)]Br to the corresponding azide species 1⋅ [Mn(CO)3N3] with sodium azide, followed by a series of [3+2] azide-alkyne cycloaddition reactions, are reported. The final liberation of the "click" products from the porous material is achieved by N-alkylation with MeBr, which regenerates starting MOF 1⋅ [Mn(CO)3(H2O)]Br and releases the organic products, as characterized by NMR spectroscopy and mass spectrometry. Once the dialkyne length exceeds the azide separation, site selectivity is lost, confirming the critical importance of isolated azide moieties for this strategy. We postulate that carefully designed MOFs can act as physical protecting groups to facilitate other site-selective and chemoselective transformations. [ABSTRACT FROM AUTHOR]
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- 2018
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8. Synthesis, isomerisation and biological properties of mononuclear ruthenium complexes containing the bis[4(4′-methyl-2,2′-bipyridyl)]-1,7-heptane ligand.
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Sun, Biyun, Southam, Hannah M., Butler, Jonathan A., Poole, Robert K., Burgun, Alexandre, Tarzia, Andrew, Keene, F. Richard, and Collins, J. Grant
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RUTHENIUM compound synthesis ,RUTHENIUM pyridyls ,HEPTANE ,ISOMERIZATION ,LIGANDS (Chemistry) ,BIOACTIVE compounds ,ANTIBACTERIAL agents - Abstract
A series of mononuclear ruthenium(ii) complexes containing the tetradentate ligand bis[4(4′-methyl-2,2′-bipyridyl)]-1,7-heptane have been synthesised and their biological properties examined. In the synthesis of the [Ru(phen′)(bb
7 )]2+ complexes (where phen′ = 1,10-phenanthroline and its 5-nitro-, 4,7-dimethyl- and 3,4,7,8-tetramethyl- derivatives), both the symmetric cis-α and non-symmetric cis-β isomers were formed. However, upon standing for a number of days (or more quickly under harsh conditions) the cis-β isomer converted to the more thermodynamically stable cis-α isomer. The minimum inhibitory concentrations (MIC) and the minimum bactericidal concentrations (MBC) of the ruthenium(ii) complexes were determined against six strains of bacteria: Gram-positive Staphylococcus aureus (S. aureus) and methicillin-resistant S. aureus (MRSA); and the Gram-negative Escherichia coli (E. coli) strains MG1655, APEC, UPEC and Pseudomonas aeruginosa (P. aeruginosa). The results showed that the [Ru(5-NO2 phen)(bb7 )]2+ complex had little or no activity against any of the bacterial strains. By contrast, for the other cis-α-[Ru(phen′)(bb7 )]2+ complexes, the antimicrobial activity increased with the degree of methylation. In particular, the cis-α-[Ru(Me4 phen)(bb7 )]2+ complex showed excellent and uniform MIC activity against all bacteria. By contrast, the MBC values for the cis-α-[Ru(Me4 phen)(bb7 )]2+ complex varied considerably across the bacteria and even within S. aureus and E. coli strains. In order to gain an understanding of the relative antimicrobial activities, the DNA-binding affinity, cellular accumulation and water–octanol partition coefficients (log P) of the ruthenium complexes were determined. Interestingly, all the [Ru(phen′)(bb7 )]2+ complexes exhibited stronger DNA binding affinity (Ka ≈ 1 × 107 M−1 ) than the well-known DNA-intercalating complex [Ru(phen)2 (dppz)]2+ (where dppz = dipyrido[3,2-a:2′,3′-c]phenazine). [ABSTRACT FROM AUTHOR]- Published
- 2018
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9. Mapping-Out Catalytic Processes in a Metal-Organic Framework with Single-Crystal X-ray Crystallography.
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Burgun, Alexandre, Coghlan, Campbell J., Huang, David M., Chen, Wenqian, Horike, Satoshi, Kitagawa, Susumu, Alvino, Jason F., Metha, Gregory F., Sumby, Christopher J., and Doonan, Christian J.
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CATALYSTS , *CRYSTALLOGRAPHY , *CRYSTAL structure , *NEUTRON diffraction , *GAS absorption & adsorption - Abstract
Single-crystal X-ray crystallography is employed to characterize the reaction species of a full catalytic carbonylation cycle within a MnII-based metal-organic framework (MOF) material. The structural insights explain why the Rh metalated MOF is catalytically competent toward the carbonylation of MeBr but only affords stoichiometric turn-over in the case of MeI. This work highlights the capability of MOFs to act as platform materials for studying single-site catalysis in heterogeneous systems. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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10. Engineering Isoreticular 2D Metal--Organic Frameworks with Inherent Structural Flexibility.
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Burgun, Alexandre, Bloch, Witold M., Doonan, Christian J., and Sumby, Christopher J.
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METAL-organic frameworks , *ANISOTROPY , *LIGANDS (Chemistry) - Abstract
The chemical mutability of metal-organic frameworks (MOFs) is an advantageous feature that allows fine-tuning of their physical and chemical properties. Herein, we report the successful isoreticulation of a MOF with an outstanding gas selectivity for CO2 versus N2: [Cu(L1)(H2O)]⋅xS (CuL1), where H2L1=bis(4-(4-carboxyphenyl)-1H-pyrazolyl)methane) and S=solvate. By modifying the steric bulk and length of the original ligand, we synthesised three new MOFs with 2D networks isoreticular to CuL1, namely [Cu(L1Me)(H2O)]⋅xS (CuL1Me), [Cu(L2)(H2O)]⋅xS (CuL2), and [Cu(L2Me)(H2O)]⋅xS (CuL2Me) (where H2L1Me=bis(4-(4-carboxyphenyl)-3,5-dimethyl-1H-pyrazolyl)methane, H2L2=bis(4-(4-carboxyphenyl)-(ethyne-2,1-yl)-1H-pyrazolyl)methane, and H2L2Me=bis(4-(4-carboxyphenyl)-(ethyne-2,1-yl)-3,5-dimethyl-1H-pyrazolyl)methane). Depending on the steric hindrance and structure metrics of the organic links, staggered and eclipsed arrangements of 2D 44 net layers were obtained. The anisotropy of the pore dimensions is proportional to the linker length (L2 and L2Me), which when increased, renders these materials nonporous. However, the more sterically demanding ligand L1Me gives a material that shows gate-opening behaviour in response to a CO2 absorbate. The synthesis and structure of an unexpected mixed-valence CuII/CuI 3D MOF, Cu3[Cu(L2Me)2]2(H2O)4]⋅xS (Cu5(L2Me)4), containing an unusual trimeric CuII node are also reported. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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11. Hydrogen adsorption in azolium and metalated N-heterocyclic carbene containing MOFs.
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Capon, Patrick K., Burgun, Alexandre, Coghlan, Campbell J., Crees, Rachel S., Doonan, Christian J., and Sumby, Christopher J.
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CARBENES , *CATALYSTS , *POLYMERIC composites , *METALATION , *IMIDAZOLES - Abstract
Azolium and metalated N-heterocyclic carbene (NHC) functionalised metal–organic frameworks (MOFs) have been investigated as adsorbents and heterogenous catalysts. Here we describe the structures of two sets of 1D polymeric structures, {[M2(μ2-HCOO)(HL)2](NO3)·xDMF}n (M = Zn, x = 1, 1; Cu, x = 1.75, 2) and {[M3(HL)4(H2O)4](NO3)2·xDMF}n (M = Co, x = 2.75, 3; Mg, x = 0, 4; Mn, x = 1.5, 5), prepared from reactions of 1,3-bis(3-carboxyphenyl)-1H-imidazol-3-ium bromide (H3LBr) with M(NO3)2·xH2O (M = Zn, Cu, Co and Mg) and MnCl2·4H2O. These pack as porous and non-porous 3D materials, respectively. In the case of the known Zn(ii) material 1, which we reveal to be porous, we also report metalation of the NHC precursor concomitant with framework synthesis to give {[Zn2(μ2-HCOO)(HL)1.6(L–Cu–Br)0.4](NO3)0.6·0.75DMF}n (1-Cu). Compounds 1, 2, and 1-Cu show H2 adsorption enthalpies of −9.9, −9.1, and −9.7 kJ mol−1 respectively, and allow the effect of micropores decorated with charged imidazolium moieties, or NHC–CuBr entities, on H2 adsorption to be probed. [ABSTRACT FROM AUTHOR]
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- 2016
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12. Endohedrally functionalised porous organic cages.
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Burgun, Alexandre, Valente, Peter, Evans, Jack D., Huang, David M., Sumby, Christopher J., and Doonan, Christian J.
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ORGANIC chemistry , *PYRIDINE derivatives , *KINETIC control , *POROUS materials , *SULFUR hexafluoride , *IMINE synthesis - Abstract
The synthesis and characterisation of two novel, functionalised porous organic cages are presented. We demonstrate that a step-wise approach to the synthesis of these robust C–C bonded cages allows for the introduction of a controlled number of endohedral pyridine functional groups. In addition, kinetic processing is used to access permanently porous morphologies. [ABSTRACT FROM AUTHOR]
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- 2016
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13. Site-specific metal and ligand substitutions in a microporous Mn2+-based metal–organic framework.
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Huxley, Michael, Coghlan, Campbell J., Burgun, Alexandre, Tarzia, Andrew, Sumida, Kenji, Sumby, Christopher J., and Doonan, Christian J.
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METAL-organic frameworks ,SUBSTITUTION reactions ,LIGANDS (Chemistry) ,POROUS materials ,MANGANESE ,CRYSTAL structure - Abstract
The precise tuning of the structural and chemical features of microporous metal–organic frameworks (MOFs) is a crucial endeavour for developing materials with properties that are suitable for specific applications. In recent times, techniques for preparing frameworks consisting of mixed-metal or ligand compositions have emerged. However, controlled spatial organisation of the components within these structures at the molecular scale is a difficult challenge, particularly when species possessing similar geometries or chemical properties are used. Here, we describe the synthesis of mixed-metal and ligand variants possessing the Mn
3 L3 (Mn-MOF-1; H2 L = bis(4-(4′-carboxyphenyl)-3,5-dimethylpyrazolyl)methane) structure type. In the case of mixed-ligand synthesis using a mixture of L and its trifluoromethyl-functionalised derivative (H2 L′ = bis(4-(4′-carboxyphenyl)-3,5-di(trifluoromethyl)pyrazolyl)methane), a mixed-ligand product in which the L′ species predominanantly occupies the pillar sites lining the pores is obtained. Meanwhile, post-synthetic metal exchange of the parent Mn3 L3 compound using Fe2+ or Fe3+ ions results in a degree of cation exchange at the trinuclear carboxylate-based clusters and metalation at the pillar bispyrazolate sites. The results demonstrate the versatility of the Mn3 L3 structure type toward both metal and ligand substitutions, and the potential utility of site-specific functionalisations in achieving even greater precision in the tuning of MOFs. [ABSTRACT FROM AUTHOR]- Published
- 2016
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14. Probing post-synthetic metallation in metal–organic frameworks: insights from X-ray crystallography.
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Bloch, Witold M., Burgun, Alexandre, Doonan, Christian J., and Sumby, Christopher J.
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METAL-organic frameworks , *ACETONITRILE synthesis , *MANGANESE chlorides , *ORGANOMETALLIC chemistry , *X-ray crystallography - Abstract
For post-synthetic metallation (PSMet) of a metal–organic framework (MOF, [Mn3(L2)(L′)] = 1) we show a solvent dependency for the form of the metallated product. PSMet of 1 with MnCl2 in ethanol leads to a single metal entity per coordinating site while acetonitrile yields a remarkably complex multiply metallated product; thus, determining the extent of metallation requires an intimate understanding of the chemistry occurring in the MOF pores. [ABSTRACT FROM AUTHOR]
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- 2015
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15. A 3-D diamondoid MOF catalyst based on in situ generated [Cu(L)2] N-heterocyclic carbene (NHC) linkers: hydroboration of CO2.
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Burgun, Alexandre, Crees, Rachel S., Doonan, Christian J., Sumby, Christopher J., and Cole, Marcus L.
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DIAMONDOIDS , *METAL-organic frameworks , *CARBENES , *HYDROBORATION , *CARBON dioxide - Abstract
A new MOF, [Zn4O{Cu(L)2}2] (1), with a 4-fold interpenetrated 3D diamondoid structure was synthesised from in situ generated [Cu(L)2] NHC linkers. MOF 1 possesses tetrahedral Zn4O nodes, which are unusually coordinated by four pairs of carboxylates from four [Cu(L)2] linkers, and 14 Å 1-D pore channels lined with [Cu(L)2] moieties that catalyse the hydroboration of CO2 [ABSTRACT FROM AUTHOR]
- Published
- 2014
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16. A 3-D diamondoid MOF catalyst based on in situ generated [Cu(L)2] N-heterocyclic carbene (NHC) linkers: hydroboration of CO2.
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Burgun, Alexandre, Crees, Rachel S., Doonan, Christian J., Sumby, Christopher J., and Cole, Marcus L.
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DIAMONDOIDS ,METAL-organic frameworks ,CARBENES ,HYDROBORATION ,CARBON dioxide - Abstract
A new MOF, [Zn
4 O{Cu(L)2 }2 ] (1), with a 4-fold interpenetrated 3D diamondoid structure was synthesised from in situ generated [Cu(L)2 ] NHC linkers. MOF 1 possesses tetrahedral Zn4 O nodes, which are unusually coordinated by four pairs of carboxylates from four [Cu(L)2 ] linkers, and 14 Å 1-D pore channels lined with [Cu(L)2] moieties that catalyse the hydroboration of CO2 [ABSTRACT FROM AUTHOR]- Published
- 2014
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17. From Molecular Wires to Molecular Resistors: TCNE,a Class-III/Class-II Mixed-Valence Chemical Switch.
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Burgun, Alexandre, Ellis, Benjamin G., Roisnel, Thierry, Skelton, Brian W., Bruce, Michael I., and Lapinte, Claude
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NANOWIRES , *MIXTURES , *VALENCE (Chemistry) , *COMPLEX compounds synthesis , *NUCLEAR magnetic resonance spectroscopy - Abstract
The binuclear complexes {Cp*(dppe)M}2{μ-CCC[C(CN)2]C[C(CN)2]CC} (2Fe, M = Fe; 2Ru,M = Ru) and {Cp*(dppe)Fe}{CCC[C(CN)2]C[C(CN)2]CC}{Ru(dppe)Cp*} (2FeRu) were obtainedby treatment of the binuclear precursorsCp*(dppe)M-CCCCCC-M′(dppe)Cp* (M =M′ = Fe, 1Fe; M = M′ = Ru, 1Ru; M = Fe, M′ = Ru, 1FeRu) with TCNE in CH2Cl2at 20 °C. Complexes 2Feand 2FeRuwere isolated as deep purple powders (82% and 87% yields,respectively), and 2Ruwas isolated as a brown-yellowsolid (55%). The paramagnetic salt [2FeRu][C3(CN)5]was also isolated in 51% yield. The structural and electronic propertiesof the new compounds were investigated by 1H, 13C, and 31P NMR, XRD analysis, cyclic voltammetry, IR andUV–vis, EPR, and NIR spectroscopies. The experimental dataclearly show that the insertion of the central −CC–triple bond of [M]–C6–[M] into tetracyanoethene(TCNE) dramatically decreases the electronic interaction between themetal termini. NIR spectroscopy of the salt [2FeRu][C3(CN)5]demonstrated that the coupling between the iron andruthenium centers is not completely removed by addition of TCNE to [1FeRu]+, but has produced a very strong attenuationof the electronic coupling from Hab=0.50 eV to Hab= 0.03 eV. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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18. Hexatriynediyl Chain Spanning Two Cp*(dppe)M Termini(M = Fe, Ru): Evidence for the Dependence of Electronic and MagneticCouplings on the Relative Orientation of the Termini.
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Burgun, Alexandre, Gendron, Frédéric, Sumby, Christopher J., Roisnel, Thierry, Cador, Olivier, Costuas, Karine, Halet, Jean-François, Bruce, Michael I., and Lapinte, Claude
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MAGNETIC coupling , *SPANNING trees , *IRON chlorides , *DELOCALIZATION energy , *ELECTRONS , *SINGLE crystals - Abstract
The binuclear complexes Cp*(dppe)FeCCCCCCM(dppe)Cp*(6, M = Fe; 8, M = Ru) were obtained ingood yield by treatment of the iron chloro complex Cp*(dppe)Fe–Cl(5) in the presence of KF with the bis(silylated) hexatriyneMe3SiCCCCCCSiMe3andthe ruthenium complex Cp*(dppe)RuCCCCCCSiMe3(7), respectively. The oxidized species 6(PF6)n(n= 1, 2) and 8(PF6)were obtained in ca. 80%yield by treatment of the parent neutral compounds with 1 or 2 equivof [Cp2Fe](PF6) in THF or dichloromethane at−78 °C. The CV of these compounds show three reversiblewaves with a separation larger than 0.5 V. The salts 6(PF6)n(n= 1, 2), and 8(PF6)were characterized by XRD. Quantumchemistry calculations performed at the DFT level on the oxidizedspecies show a strong contribution of the −C6–spacer to the delocalization of the spin density. IR spectra analyzedwith the support of TD-DFT calculations are consistent with the delocalizationof the odd electron on the fast IR time scale for the two mixed-valencecomplexes 6(PF6)and 8(PF6). CombinedESR measurements on rigid glass and on single crystal samples clearlyestablish that the electronic properties of MV species and particularlytheir magnetic anisotropies depend on the conformation of the molecules.In the case of the doubly oxidized species 6(PF6)2, which carriestwo unpaired electrons, it is shown that the singlet vs triplet groundstates can be inverted by the rotation of one metal end with respectto the other around the all-carbon chain axis. Very strong NIR bandsare found for the symmetric 6(PF6)and nonsymmetric 8(PF6)MV (mixed-valence) derivatives allowing thedetermination of very large electronic couplings (Hab= 3070 and 4025 cm–1, respectively). [ABSTRACT FROM AUTHOR]
- Published
- 2014
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19. Straightforward Access to Tetrametallic Complexes with a Square Array by Oxidative Dimerization of Organometallic Wires.
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Burgun, Alexandre, Gendron, Frédéric, Schauer, Phil A., Skelton, Brian W., Low, Paul J., Costuas, Karine, Halet, Jean-François, Bruce, Michael I., and Lapinte, Claude
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METAL complexes , *DIMERIZATION , *ORGANOMETALLIC chemistry , *BIMETALLIC catalysts , *RUTHENIUM , *CYCLIC voltammetry - Abstract
The bimetallic ruthenium complex {Cp(dppe)Ru}2(μ-C≡CC≡CC≡C) (3; Cp = cyclopentadienyl, dppe = 1,2-bis(diphenylphosphino)ethane) has been prepared and the molecular structure determined. The cyclic voltammogram of 3 is characterized by three reversible one-electron events with a large potential difference between the two first waves (ΔE° = 0.44 V), indicating the large thermodynamic stability of the MV (mixed-valence) 3(PF6), which can be considered as a class III MV complex. The complex 3(PF6) was quantitatively prepared by treatment of 3 with 1 equiv of [FeCp2](PF6) at −78 °C and characterized by EPR spectroscopy. Above −10 °C, solutions of 3(PF6) provide the asymmetric tetranuclear complex {cyclo-C([Ru])C(CCCC[Ru])C(CC[Ru])C(CC[Ru])}(PF6)2 (4(PF6)2; [Ru] = Cp(dppe)Ru) which was formed regiospecifically and isolated in 92% yield. Thus, despite the thermodynamic stability of the monocation radical 3(PF6) as evidenced by the electrochemical data, and the extensively delocalized electronic structure, a slow dimerization reaction takes place, affording a stable, tetranuclear complex. The new compound was characterized by a single-crystal X-ray diffraction study, cyclic voltammetry, and multinuclear NMR, IR, UV-vis, and near-IR spectroscopy, and the data were analyzed with the support of quantum chemical investigations at the DFT level of theory. The regiospecificity of the dimerization reaction is controlled by a balance of steric and electronic factors, which favors intermolecular (Cα + Cγ) radical coupling. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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20. Some Ruthenium Derivatives of Penta-1,4-diyn-3-one.
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Bruce, Michael I., Burgun, Alexandre, Fox, Mark A., Jevric, Martyn, Low, Paul J., Nicholson, Brian K., Parker, Christian R., Skelton, Brian W., White, Allan H., and Zaitseva, Natasha N.
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RUTHENIUM compounds , *CHEMICAL derivatives , *OXALYL chloride , *METHYLATION , *CHEMICAL reactions , *CRYSTAL structure - Abstract
Thereaction between Ru(CCH)(dppe)Cp* (1)and oxalyl chloride affords ({Ru(dppe)Cp*}CC)2CO(2) in 72% yield. Methylation (MeOTf) of 2occurs first on the carbonyl oxygen, affording [({Ru(dppe)Cp*}CC)2C(OMe)]OTf ([3]OTf). A second methylation of[3]+on the alkynyl Cβproceedsslowly, affording [{Cp*(dppe)Ru}CCMeC(OMe)CC{Ru(dppe)Cp*}][OTf]2([4][OTf]2), whereas protonationof [3]+occurs readily to give crystallographicallycharacterized [{Cp*(dppe)Ru}CCHC(OMe)CC{Ru(dppe)Cp*}][OTf]2([5][OTf]2). The molecular structures of[3]OTf and [5][OTf]2suggestthat polarization by the CO group results in significant contributionsfrom the alkynyl-allenylidene or alkynyl-carbyne mesomers, respectively.Reaction of 2in refluxing MeOH containing [NH4]PF6results in partial methanolysis to give Ru{CCC(O)CHCH(OMe)}(dppe)Cp*(6). Knövenagel condensation of 2with CH2(CN)2affords {[Ru(dppe)Cp*]CC}2CC(CN)2(7). The related asymmetriccomplex {Cp*(dppe)Ru}CC[CC(CN)2]CCCC{Ru(dppe)Cp*}(8) was obtained from the reaction between Ru{CCC(CN)C(CN)2}(dppe)Cp* and lithiated Ru(CCCCH)(dppe)Cp*.Single-crystal structural determinations of 2, [3]OTf, [5][OTf]2, 6, 7, and 8are reported, together with a supportingcomputational study of relevant electronic structures. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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21. Triazolium-Containing Metal]Organic Frameworks: Control of Catenation in 2D Copper(II) Paddlewheel Structures.
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Burgun, Alexandre, Doonan, Christian J., and Sumby, Christopher J.
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METAL-organic frameworks , *COPPER structure-activity relationships , *CATALYSIS , *TRIAZOLES synthesis , *RING formation (Chemistry) - Abstract
One approach to exploit metal-organic frameworks (MOFs) as heterogeneous catalyst platforms requires the development of materials containing groups that can be utilised to anchor a catalytic moiety into the links within the structure. Here we report the synthesis of the first integrated triazolium-containing MOF linker and the first MOFs containing linkers of this type. 1,4-Bis(4-benzoic acid)-1-methyl-1H-1,2,3-triazolium chloride, H[sub 2]L1[sup Me], was synthesised in three steps by a 'click' reaction of methyl 4-ethynylbenzoate with methyl 4-azidobenzoate, methylation using methyl triflate, followed by ester hydrolysis in overall 74% yield. The equivalent neutral triazole precursor, 1,4-bis(4-benzoic acid)-1 H-1,2,3-triazole hydrochloride, H[sub 2]L1(HCl), was also prepared and a comparison of the chemistry with Zn(NO[sub 3])[sub 2]-6H[sub 2]O and Cu(NO3)[sub 2] л 3H[sub 2]O is presented. The results support the use of reaction conditions to control interpenetration and provide additional evidence that the charge on structurally similar ligands can drastically alter the types of structures that are accessible due to the requirements for charge balance in the final product. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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22. Oxidative Activation of Aryldiynyl–Iron Complexes: Regioselective Dimerization.
- Author
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Burgun, Alexandre, Gendron, Frédéric, Roisnel, Thierry, Sinbandhit, Sourisak, Costuas, Karine, Halet, Jean-François, Bruce, Michael I., and Lapinte, Claude
- Published
- 2013
- Full Text
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23. Kinetically Controlled Porosity in a Robust Organic Cage Material.
- Author
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Avellaneda, Antonio, Valente, Peter, Burgun, Alexandre, Evans, Jack D., Markwell ‐ Heys, Adrian W., Rankine, Damien, Nielsen, David J., Hill, Matthew R., Sumby, Christopher J., and Doonan, Christian J.
- Abstract
Geschwindigkeit ist alles: Ein neuer kristalliner mikroporöser Feststoff wurde hergestellt, der aus diskreten organischen Käfigen besteht, die ausschließlich aus Kohlenstoff ‐ Kohlenstoff ‐ Bindungen aufgebaut sind. Die Porosität des Materials kann leicht über die Abscheidungskinetik eingestellt werden, wodurch wahlweise poröse oder nichtporöse Polymorphe erhältlich sind. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
24. Iron and Ruthenium Ï-Polyynylsof theGeneral Formula [{M(dppe)Cp*}â(Cî¼C)nâR]0/(M = Fe, Ru): An Experimental andTheoretical Investigation.
- Author
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Gendron, FreÌdeÌric, Burgun, Alexandre, Skelton, Brian W., White, Allan H., Roisnel, Thierry, Bruce, Michael I., Halet, Jean-François, Lapinte, Claude, and Costuas, Karine
- Subjects
- *
RUTHENIUM compounds , *CHEMICAL synthesis , *ANISOTROPY , *FREE radical reactions , *CHEMICAL kinetics , *CHEMICAL stability - Abstract
Two series of metal-polyynyl complexes of iron and rutheniumofgeneral formula [{M(dppe)Cp*}â(Cî¼C)nâR]0/(M = Fe, Ru; R = H, Ph, SiMe3, Au(PPh3); n= 1â3), have beensynthesized, characterized, and theoretically analyzed. The resultsprovide a comprehensive description of the effect of the length ofthe conjugated carbon chain and the role of the nature of the metalatom and the terminal substituent on their neutral and oxidized states.For the latter, the spin density found on the carbon chain is a sourceof instability; e.g., for R = Au(PPh3), the oxidized compoundsare much more accessible electrochemically than the rest of the seriesbut are susceptible to radical attack. Of particular interest is theuse of joint experimental and theoretical EPR studies, which allowelucidation of the differences of behavior within the two series.It reveals that the atomic spin density on the metal is not a sufficientcriterion to evaluate EPR anisotropy but that the specific nodal propertiesof the frontier spinâorbitals highly influence the EPR components.The localization of the spin density on specific carbon atoms of theconjugated chain (even numbered) opens up the possibility of buildingextended systems by targeted radical reactions. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
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25. Reactions of 7,7,8,8-TetracyanoquinodimethanewithPoly-ynyl Ruthenium and Iron Complexes.
- Author
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Bruce, Michael I., Burgun, Alexandre, Grelaud, Guillaume, Lapinte, Claude, Parker, Christian R., Roisnel, Thierry, Skelton, Brian W., and Zaitseva, Natasha N.
- Subjects
- *
CHEMICAL reactions , *TETRACYANOQUINODIMETHANE , *RUTHENIUM compounds , *IRON compounds , *COMPLEX compounds , *OXIDATION-reduction reaction , *SINGLE crystals - Abstract
The reaction of tetracyanoquinodimethane (TCNQ) withRu(Cî¼CCî¼CH)(dppe)Cp*(5) at the outer (from Ru) Cî¼C triple bond givesη1-(butadienyl)ethynyl Ru{Cî¼CC[CHî»C(CN)2]î»C6H4î»C(CN)2}(dppe)Cp (8), which reacts with a second equivalentof diynyl-Ru complex to give {Ru(dppe)Cp*}{Cî¼CC[î»C6H4î»C(CN)2]CHî»CHC[î»C(CN)2]Cî¼C}{Ru(dppe)Cp*} (9). The Ph-substitutedcomplexes M{Cî¼CCî¼CPh}(dppe)Cp* (M = Fe 6-Fe, Ru 6-Ru) and Ru{(Cî¼C)3Ph}(PPh3)2Cp (7) react with TCNQ to give theη1-(butadienyl)ethynylsM{Cî¼CC[CPhî»C(CN)2]î»C6H4î»C(CN)2}(dppe)Cp (10-Fe, 10-Ru) and Ru{Cî¼CC[C(Cî¼CPh)î»C(CN)2]î»C6H4î»C(CN)2}(PPh3)2Cp (11), respectively.Single-crystal X-ray diffraction molecular structure determinationsfor 8â11have been carried out. Inthe Fe series, we suggest that the initial step of the mechanism involveselectron transfer to form the [TCNQ]ââ¢saltof the diynyl-iron cation, followed by CâC bond formation togive a zwitterionic intermediate. Isolated products can be rationalizedby further reaction involving [2 2]-cycloaddition of one of theCî»C(CN)2groups of TCNQ to a Cî¼C triple bondof the metal poly-ynyl complex and a subsequent ring-opening reactionof the resulting (unobserved) cyclobutenyl intermediate. On the basisof X-ray diffraction data, redox potential determinations, and 57Fe MoÌssbauer and UVâvis spectroscopies, theelectronic structures of the new compounds contain significant contributionsfrom polarized mesomers involving charge transfer from the electron-richmetalâligand fragment to the cyanocarbon ligand via the conjugatedunsaturated carbon linker. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
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26. Reactions of 7,7,8,8-Tetracyanoquinodimethane (TCNQ) with Alkynyl-Iron- and -Ruthenium Complexes: Synthesis of Ru{C=CC(CN)=C[sub 6]H[sub 4]=C(CN)[sub 2]}(PPh[sub 3])[sub 2]Cp, a New Donor-Acceptor Molecular Array*.
- Author
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Bruce, Michael I., Burgun, Alexandre, Grelaud, Guillaume, Lapinte, Claude, Skelton, Brian W., and Zaitseva, Natasha N.
- Subjects
- *
TETRACYANOQUINODIMETHANE , *CHEMICAL reactions , *RUTHENIUM compounds , *POLYZWITTERIONS , *HYDROGEN-ion concentration , *TRANSITION metals - Abstract
Reactions of 7,7,8,8-tetracyanoquinodimethane (TCNQ) with the alkynyl-iron and ruthenium complexes [M](C=CR) {[M] = Fe(dppe)Cp*, Ru(PPh[sub 3])[sub 2]Cp; R = H, Ph} are described. The iron complex Fe(C=CPh)(dppe)Cp* (2a) is oxidized by TCNQ to give the kinetically stable salt [2a[sup * +]][TCNQ][sup * -] . Displacement of [TCNQ][sup * -] is achieved by ionic metathesis upon addition of KPF[sub 6] to produce [2a[sup * +]]PF[sub 6]. In contrast, Fe(C=CH)(dppe)Cp* (2b) reacted with TCNQ to give a mixture of compounds containing Fe(=C=CH[sub 2])(dppe)Cp* (3a), {Fe(dppe)Cp*}[sub 2](μ-C=CHCH=C) (3b), and the zwitterionic complex Fe[sup +]{=C=CHC(CN)[sub 2]C[sub 6]H[sub 4]C[sup -](CN)[sub 2]}(dppe)Cp* (3c). In contrast, the reaction of TCNQ with Ru(C=CR)(PPh[sub 3])[sub 2]Cp (4a, R = Ph; 4b, R = H) gave selectively the zwitterionic vinylidenes Ru[sup +]{=C=CRC(CN)[sub 2]C[sub 6]H[sub 4]C[sup -](CN)[sub 2]}(PPh[sub 3])[sub 2]Cp (5a, R = Ph; 5b, R = H), in which the Ru centres are positively charged and the counter-anion is located on the further C(CN)[sub 2] group. On heating 5b, elimination of HCN affords Ru{C=CC(CN)=C[sub 6]H[sub 4]=C(CN)[sub 2]}(PPh[sub 3])[sub 2]Cp (1), while similar treatment of 5a gives Ru{[sup 3]-C(CN)[sub 2]CPh=C[sub 6]H[sub 4]=C(CN)[sub 2]}(PPh[sub 3])Cp (6) with loss of PPh[sub 3]. X-ray structures of 1, 5a, and 6, cyclic voltammetry, and UV-vis spectroscopy of 1 provided evidence for the electronic structures of the new complexes. Organometallics with various donor-bridge-acceptor arrangements allow investigation of the key factors affecting the properties of these multifunctional molecular systems. Herein, reactions of 7,7,8,8-tetracyanoquinodimethane (TCNQ) with Fe(C=CR)(dppe)Cp* and Ru(C=CR)(PPh[sub 3])[sub 2]Cp (R = H, Ph) are described. Formed are the mono-cation (by oxidation in the iron series), zwitterionic complexes, and complexes formed by regioselective [2 + 2]-cycloaddition and subsequent ring-opening reactions; elimination of HCN (in the ruthenium series) was also observed. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
27. Polarized Complexes Obtained by Regiospecific Substitution of a CN Group in Ru{CCC(CN)C(CN)2}(dppe)Cp* (Cp* = η-C5Me5).
- Author
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Bruce, Michael I., Burgun, Alexandre, Nicholson, Brian K., Parker, Christian R., Skelton, Brian W., and White, Allan H.
- Subjects
- *
ISOMERIZATION , *MESITYLENE , *PHOSPHINE oxides , *NUCLEOPHILES , *X-ray diffraction - Abstract
The complex Ru{CCC(CN)C(CN)2}(dppe)Cp* (1), containing the new tricyanovinylethynyl (3,4,4-tricyanobut-3-en-1-ynyl) ligand, undergoes ready substitution of the 3-cyano group by nucleophiles (Nu) such as H, Me, Pri, Bu, But, mesityl, OMe, OBut, OCH2CHCH2, NHEt, NEt2, and PPh2 to give Ru{CCC(Nu)C(CN)2}(dppe)Cp*. The X-ray diffraction structures of several of the resulting complexes are reported and, for the mesityl and PPh2 products, show that isomerization to the 3,5-dimethylbenzyl and oxidation to the phosphine oxide have respectively occurred. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
28. Polarized Complexes Obtained by Regiospecific Substitution of a CN Group in Ru{CCC(CN)C(CN)2}(dppe)Cp* (Cp* = η-C5Me5).
- Author
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Bruce, Michael I., Burgun, Alexandre, Nicholson, Brian K., Parker, Christian R., Skelton, Brian W., and White, Allan H.
- Published
- 2012
- Full Text
- View/download PDF
29. Syntheses and Structural Studies of Several Diynyl-Ruthenium Complexes and their Adducts with Cyano-Alkenes.
- Author
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Bruce, Michael I., Burgun, Alexandre, Grelaud, Guillaume, Jevric, Martyn, Nicholson, Brian K., Skelton, Brian W., White, Allan H., and Zaitseva, Natasha N.
- Published
- 2011
- Full Text
- View/download PDF
30. Some ruthenium complexes of fluorinated alkynylcyclopentenes
- Author
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Bruce, Michael I., Burgun, Alexandre, Parker, Christian R., and Skelton, Brian W.
- Subjects
- *
METAL complexes , *ORGANORUTHENIUM compounds , *CYCLOALKANES , *HYDROLYSIS , *MOLECULAR structure , *FLUOROCARBONS , *LIGANDS (Chemistry) , *ELECTROCHEMICAL analysis - Abstract
Reactions between 1,2-dichlorohexafluorocyclopentene and Ru(C≡CH)(dppe)Cp∗ or Ru(C≡CC≡CLi)(dppe)Cp∗ have given Ru(C≡C-c-C5F6Cl-2)(dppe)Cp∗ 4 and Ru(C≡CC≡C-c-C5F6Cl-2)(dppe)Cp∗ 7, respectively. Ready hydrolysis of 4 to the ketone Ru{C≡C[c-C5F4Cl(O)]}(dppe)Cp∗ 5 occurs, which can be converted to Ru{C≡C(c-C5F4Cl[=C(CN)2])}(dppe)Cp∗ 6 by treatment with CH2(CN)2/basic alumina. Spectroscopic, electrochemical and XRD structural studies for 4–7 are reported: for 6, these suggest that the cyanated fluorocarbon ligand is a very powerful electron-withdrawing group. [Copyright &y& Elsevier]
- Published
- 2010
- Full Text
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31. A Facile Synthesis Procedure for Sulfonated Aniline Oligomers with Distinct Microstructures.
- Author
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Karunagaran, Ramesh, Coghlan, Campbell, Tran, Diana, Tung, Tran Thanh, Burgun, Alexandre, Doonan, Christian, and Losic, Dusan
- Subjects
ANILINE ,OLIGOMERS ,MICROSTRUCTURE ,CHEMICAL reactions ,MONOMERS - Abstract
Well-defined sulfonated aniline oligomer (SAO) microstructures with rod and flake morphologies were successfully synthesized using an aniline and oxidant with a molar ratio of 10:1 in ethanol and acidic conditions (pH 4.8). The synthesized oligomers showed excellent dispersibility and assembled as well-defined structures in contrast to the shapeless aggregated material produced in a water medium. The synergistic effects among the monomer concentration, oxidant concentration, pH, and reaction medium are shown to be controlling parameters to generate SAO microstructures with distinct morphologies, whether micro sheets or micro rods. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
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