| 1. |
- Ekengard, Erik, et al.
(författare)
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Antimalarial activity of ruthenium(ii) and osmium(ii) arene complexes with mono- and bidentate chloroquine analogue ligands.
- 2015
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9234 .- 1477-9226. ; 44:44, s. 19314-19329
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Tidskriftsartikel (refereegranskat)abstract
- Eight new ruthenium and five new osmium p-cymene half-sandwich complexes have been synthesized, characterized and evaluated for antimalarial activity. All complexes contain ligands that are based on a 4-chloroquinoline framework related to the antimalarial drug chloroquine. Ligands are salicylaldimine derivatives, where = N-(2-((2-hydroxyphenyl)methylimino)ethyl)-7-chloroquinolin-4-amine, and contain non-hydrogen substituents in the 3-position of the salicylaldimine ring, viz. F, Cl, Br, I, NO2, OMe and (t)Bu for , respectively. Ligand is also a salicylaldimine-containing ligand with substitutions in both 3- and 5-positions of the salicylaldimine moiety, i.e. N-(2-((2-hydroxy-3,5-di-tert-butylphenyl)methyl-imino)ethyl)-7-chloroquinolin-4-amine, while is N-(2-((1-methyl-1H-imidazol-2-yl)methylamino)ethyl)-7-chloroquinolin-4-amine) The half sandwich metal complexes that have been investigated are [Ru(η(6)-cym)()Cl] (Ru--Ru-, cym = p-cymene), [Os(η(6)-cym)()Cl] (Os--Os-, Os-, and Os-), [M(η(6)-cym)()Cl2] (M = Ru, Ru-; M = Os, Os-) and [M(η(6)-cym)()Cl]Cl (M = Ru, Ru-; M = Os, Os-). In complexes Ru--Ru- and Ru-, Os--Os-, Os- and Os- and Os-, the ligands were found to coordinate as bidentate N,O- and N,N-chelates, while in complexes Ru- and Os-, monodentate coordination of the ligands through the quinoline nitrogen was established. The antimalarial activity of the new ligands and complexes was evaluated against chloroquine sensitive (NF54 and D10) and chloroquine resistant (Dd2) Plasmodium falciparum malaria parasite strains. Coordination of ruthenium and osmium arene moieties to the ligands resulted in lower antiplasmodial activities relative to the free ligands, but the resistance index is better for the ruthenium complexes compared to chloroquine. Overall, osmium complexes appeared to be less active than the corresponding ruthenium complexes.
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| 2. |
- Hizbullah, Lintang, et al.
(författare)
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Synthesis of phosphine derivatives of [Fe2(CO)6(μ-sdt)] (sdt = SCH2SCH2S) and investigation of their proton reduction capabilities
- 2023
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Ingår i: Journal of Inorganic Biochemistry. - 0162-0134. ; 246
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Tidskriftsartikel (refereegranskat)abstract
- The reactions of [Fe2(CO)6(μ-sdt)] (1) (sdt = SCH2SCH2S) with phosphine ligands have been investigated. Treatment of 1 with dppm (bis(diphenylphosphino)methane) or dcpm (bis(dicyclohexylphosphino)methane) affords the diphosphine-bridged products [Fe2(CO)4(μ-sdt)(μ-dppm)] (2) and [Fe2(CO)4(μ-sdt)(μ-dcpm)] (3), respectively. The complex [Fe2(CO)4(μ-sdt)(κ2-dppv)] (4) with a chelating diphosphine was obtained by reacting 1 with dppv (cis-1,2-bis(diphenylphosphino)ethene). Reaction of 1 with dppe (1,2-bis(diphenylphosphino)ethane) produces [{Fe2(CO)4(μ-sdt)}2(μ-κ1-dppe)] (5) in which the diphosphine forms an intermolecular bridge between two diiron cluster fragments. Three products were obtained when dppf (1,1′-bis(diphenylphosphino)ferrocene) was introduced to complex 1; they were [Fe2(CO)5(μ-sdt)(κ1-dppfO)] (6), the previously known [{Fe2(CO)5(μ-sdt)}2(μ-κ1-κ1-dppf)] (7), and [Fe2(CO)4(μ-sdt)(μ-dppf)] (8), with complex 8 being produced in highest yield. Single crystal X-ray diffraction analysis was performed on compounds 2, 3 and 8. All structures reveal the adoption of an anti-arrangement of the dithiolate bridges, while the diphosphines occupy dibasal positions. Infra-red spectroscopy indicates that the mono-substituted complexes 5, 6, and 7 are inert to protonation by HBF4.Et2O, but complexes 2, 3, 4 and [Fe2(CO)5(μ-sdt)(κ1-PPh3)] (9) show shifts of their ν(C-O) resonances that indicate that protons bind to the metal cores of the clusters. Addition of the one-electron oxidant [Cp2Fe]PF6 does not lead to any discernable shift in the IR resonances. The redox chemistry of the complexes was investigated by cyclic voltammetry, and the abilities of complexes to catalyze electrochemical proton reduction were examined.
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| 3. |
- Hossain, Md Kamal, et al.
(författare)
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An experimental and theoretical study of a heptacoordinated tungsten(VI) complex of a noninnocent phenylenediamine bis(phenolate) ligand
- 2018
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Ingår i: Inorganic Chemistry Communications. - : Elsevier BV. - 1387-7003. ; 93, s. 149-152
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Tidskriftsartikel (refereegranskat)abstract
- [W(N2O2)(HN2O2)] (H4N2O2 = N,N′-bis(3,5-di-tert-butyl-2-hydroxyphenyl)-1,2-phenylenediamine) with a noninnocent ligand was formed by reaction of the alkoxide precursor [W(eg)3] (eg = the 1,2-ethanediolate dianion) with two equivalents of ligand. The phenol groups on one of the ligands are completely deprotonated and the ligand coordinates in a tetradentate fashion, whereas the other ligand is tridentate with one phenol having an intact OH group. The molecular structure, magnetic measurements, EPR spectroscopy, and density functional theory calculations indicate that the complex is a stable radical with the odd electron situated on the tridentate amidophenoxide ligand. The formal oxidation state of the metal center is W(VI), with the paramagnetic properties being due to the unpaired electron on the ligand.
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| 4. |
- Hossain, Md Kamal, et al.
(författare)
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Oxidovanadium(V) complexes with tridentate hydrazone ligands as oxygen atom transfer catalysts
- 2024
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Ingår i: Polyhedron. - 0277-5387. ; 258
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Tidskriftsartikel (refereegranskat)abstract
- Four isostructural oxovanadium(V) complexes with hydrazone ligands have been synthesised, characterised, and evaluated as epoxidation and sulfoxidation catalysts. The reactions between [VO(acac)2] (acac– = acetylacetonate) and H2Ln (n = 1–4), precursors for monoanionic tridentate hydrazone ligands, afford complexes formulated as [VO(Ln)(bzh)·MeOH] (1–4) when bidentate benzohydroxamic acid (Hbzh) is included as a co-ligand. Single crystal X-ray structure analyses showed that complexes 1–3 have a distorted octahedral coordination geometry with an O5N coordination environment. Cyclic voltammetry showed that all complexes undergo two quasi-irreversible reduction peaks and a single irreversible oxidation peak. The bonding in 1 has been investigated by electronic structure calculations, and these data are discussed with respect to the electrochemical results. Complexes 1–4 were tested as catalysts for the epoxidation of cis-cyclooctene at 50 °C and sulfoxidation of methyl-p-tolylsulfide at room temperature using tert-butyl hydroperoxide (tBuOOH) and aqueous H2O2 as the terminal oxidants.
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| 5. |
- Hossain, Md Kamal, et al.
(författare)
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Oxovanadium(V) complexes with tripodal bisphenolate and monophenolate ligands : Syntheses, structures and catalytic activities
- 2019
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Ingår i: Inorganica Chimica Acta. - : Elsevier BV. - 0020-1693. ; 487, s. 112-119
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Tidskriftsartikel (refereegranskat)abstract
- The reactions between [VO(acac)2] (acac– = acetylacetonate) and the tripodal amino bisphenols 6,6′-(((2-morpholinoethyl)azanediyl)bis(methylene))bis(2,4-di-tert-butylphenol) (H2L1) and 6,6′-(((thiophen-2-ylmethyl)azanediyl)bis(methylene))bis(2,4-di-tert-butylphenol) (H2L2) as well as the tetradentate amino phenol 2,2′-((3,5-di-tert-butyl-2-hydroxybenzyl)azanediyl)bis(ethan-1-ol) (H3L3) afford the complexes [VO(L1)(OMe)] (1), [VO(L2)(acac)] (2) and [VO(L3)] (3), correspondingly. Complexes 1 and 3 can also be prepared using VOSO4·xH2O or [VO(OPr)3] as vanadium precursors. When [VO(acac)2] or VOSO4·xH2O is used, mononuclear oxovanadium(V) complexes are formed upon oxidation of the metal precursor. Single crystal X-ray structure analysis show that complexes 1 and 2 have distorted octahedral coordination spheres, in which the amino bisphenolate coordinates in a tetradentate or tridentate manner, respectively, and the coordination spheres are completed by methoxy or acetylacetonato ligands. Complex 3 has a slightly distorted trigonal bipyramidal geometry with an NO4 coordination environment. All three complexes can catalyze epoxidation of cis-cyclooctene at 50 °C with tert-butyl hydroperoxide (TBHP) or H2O2 as an oxygen source, and sulfoxidation of thioanisole or methyl-p-tolylsulfide proceeds at 25 °C using the same oxidants.
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| 6. |
- Li, Yong, et al.
(författare)
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Non-heme FeIV=O complexes supported by four new pentadentate ligands : reactivity towards H- and O-atom transfer processes
- 2023
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Ingår i: Inorganic Chemistry. - 1520-510X. ; 62:45, s. 18338-18356
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Tidskriftsartikel (refereegranskat)abstract
- Four new pentadentate N5-donor ligands, [N-(1-methyl-2-imidazolyl)methyl-N-(2-pyridyl)-methyl-N-(bis-2-pyridylmethyl)-amine] (L1), [N-bis(1-methyl-2-imidazolyl)methyl-N-(bis-2-pyridylmethyl)amine] (L2), (N-(isoquinolin-3-ylmethyl)-1,1-di(pyridin-2-yl)-N-(pyridin-2-ylmethyl)methanamine (L3) and N,N-bis(isoquinolin-3-ylmethyl)-1,1-di(pyridin-2-yl)methanamine (L4), have been synthesized based on the N4Py ligand framework, where one or two pyridyl arms of the N4Py parent are replaced by (N-methyl)imidazolyl or N-(isoquinolin-3-ylmethyl) moieties. Using these four pentadentate ligands, the mononuclear complexes [FeII(CH3CN)(L1)]2+ (1a), [FeII(CH3CN)(L2)]2+ (2a), [FeII(CH3CN)(L3)]2+ (3a) and [FeII(CH3CN)(L4)]2+ (4a) have been synthesized and characterized. The half-wave potentials (E1/2) of the complexes become more positive in the order: 2a < 1a < 4a 3a [Fe(N4Py)(CH3CN)]2+. The order of oxidation potentials correlates well with the Fe-Namine distances observed by crystallography, which are 2a 1a 4a 3a [Fe(N4Py)(CH3CN)]2+. The corresponding ferryl complexes [FeIV(O)(L1)]2+ (1b), [FeIV(O)(L2)]2+ (2b), [FeIV(O)(L3)]2+ (3b), and [FeIV(O)(L4)]2+ (4b) could be prepared by reaction of the ferrous complexes with isopropyl 2-iodoxybenzoate (IBX ester) in acetonitrile. The greenish complexes 3b and 4b could also be isolated in the solid state by reaction of the ferrous complexes in CH3CN with ceric ammonium nitrate in water. Mössbauer spectroscopy and magnetic measurements (SQUID) show that the four complexes 1b, 2b, 3b and 4b are low-spin (S = 1) FeIV=O complexes. UV/Vis spectra of the four FeIV=O complexes in acetonitrile show typical long wavelength absorptions around 700 nm, which are expected for FeIV=O complexes with N4Py-type ligands. The wavelengths of these absorptions decrease in the following order: 721 nm (2b) > 706 nm (1b) > 696 nm (4b) > 695 nm (3b) = 695 nm ([FeIV(O) (N4Py)]2+), indicating that the replacement of pyridyl arms with (N-methyl) imidazolyl moieties makes L1 and L2 exert weaker ligand fields than the parent N4Py ligand, while the ligand field strengths of L3 and L4 are similar to the N4Py parent despite the replacement of pyridyl arms with N-(isoquinolin-3-ylmethyl) moieties. Consequently, complexes 1b and 2b tend to be less stable than the parent [FeIV(O)(N4Py)]2+ complex: the half-life sequence at room temperature is 1.67 h (2b) < 16 h (1b) < 45 h (4b) < 63 h (3b) ≈ 60 h ([FeIV(O)(N4Py)]2+). Compared to the parent complex, 1b and 2b exhibit enhanced reactivity in both oxidation of thioanisole by oxygen atom transfer (OAT) reaction and oxygenation of C-H bonds of aromatic and aliphatic substrates, presumed to occur via an oxygen rebound process. Furthermore, second-order rate constants for hydrogen atom transfer (HAT) reactions affected by the ferryl complexes can be directly related to the C-H bond dissociation energies of a range of substrates that have been studied. Using either IBX ester or H2O2 as oxidant, all four new FeII complexes display good performance in catalytic reactions involving both HAT and OAT reactions.
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| 7. |
- Mitra, Mainak, et al.
(författare)
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Nonheme Fe(IV) Oxo Complexes of Two New Pentadentate Ligands and Their Hydrogen-Atom and Oxygen-Atom Transfer Reactions
- 2015
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 1520-510X .- 0020-1669. ; 54:15, s. 7152-7164
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Tidskriftsartikel (refereegranskat)abstract
- Two new pentadentate {N5} donor ligands based on the N4Py (N4Py = N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine) framework have been synthesized, viz. [N-(1-methyl-2-benzimidazolyl)methyl-N-(2-pyridyl)methyl-N-(bis-2-pyridyl methyl)amine] (L1) and [N-bis(1-methyl-2-benzimidazolyl)methyl-N-(bis-2-pyridylmethyl)amine] (L2), where one or two pyridyl arms of N4Py have been replaced by corresponding (N-methyl)benzimidazolyl-containing arms. The complexes [FeII(CH3CN)(L)]2+ (L = L1 (1); L2 (2)) were synthesized, and reaction of these ferrous complexes with iodosylbenzene led to the formation of the ferryl complexes [FeIV(O)(L)]2+ (L = L1 (3); L2 (4)), which were characterized by UV–vis spectroscopy, high resolution mass spectrometry, and Mössbauer spectroscopy. Complexes 3 and 4 are relatively stable with half-lives at room temperature of 40 h (L = L1) and 2.5 h (L = L2). The redox potentials of 1 and 2, as well as the visible spectra of 3 and 4, indicate that the ligand field weakens as ligand pyridyl substituents are progressively substituted by (N-methyl)benzimidazolyl moieties. The reactivities of 3 and 4 in hydrogen-atom transfer (HAT) and oxygen-atom transfer (OAT) reactions show that both complexes exhibit enhanced reactivities when compared to the analogous N4Py complex ([FeIV(O)(N4Py)]2+), and that the normalized HAT rates increase by approximately 1 order of magnitude for each replacement of a pyridyl moiety; i.e., [FeIV(O)(L2)]2+ exhibits the highest rates. The second-order HAT rate constants can be directly related to the substrate C–H bond dissociation energies. Computational modeling of the HAT reactions indicates that the reaction proceeds via a high spin transition state.
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| 8. |
- Nelana, Simphiwe M, et al.
(författare)
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Unconjugated diimine palladium complexes as Heck coupling catalysts
- 2008
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Ingår i: Journal of Molecular Catalysis A: Chemical. - : Elsevier BV. - 1381-1169. ; 285:1-2, s. 72-78
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Tidskriftsartikel (refereegranskat)abstract
- Four unconjugated diimine palladium complexes have been synthesized, and spectroscopically and structurally characterized. All four palladium complexes were used as catalysts in the Heck coupling reaction between iodobenzene and methyl acrylate or butyl acrylate with very good conversion to either methyl (2E)-3-phenylacrylate or butyl (2E)-3-phenylacrylate.
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| 9. |
- Nilsson, Jessica, et al.
(författare)
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Bis- and tris(pyridyl)amine-oxidovanadium complexes: characteristics and insulin-mimetic potential.
- 2009
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9234 .- 1477-9226. ; :38, s. 7902-7911
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Tidskriftsartikel (refereegranskat)abstract
- Two novel vanadium complexes, [V(IV)O(bp-O)(HSO4)] (1) and [V(IV)O(bp-OH)Cl2] x CH3OH (2 x CH3OH), where bp-OH is 2-{[bis(pyrid-2-yl)methyl]amine}methylphenol, were prepared and structurally characterised. EPR spectra of methanol solutions of 2 suggest exchange of Cl- for CH3OH and partial conversion to [VO(bp-OH)(CH3OH)3]2+. Speciation studies on the VO2+-bpOH system in a water/dmso mixture (4:1 v/v) revealed [VO(bp-O)(H2O)n]+ as the dominating species in the pH range 2-7. The insulin-mimetic properties of 1 and 2, [V(IV)O(SO4)tpa] (3), [V(IV)O(pic-trpMe)2] (5) and the new mixed-ligand complexes [V(V)O(pic-trpH)tpa]Cl2 (4Cl2) and [V(V)O(pic-OEt)tpa]Cl2 (6Cl2), tpa = tris(pyrid-2-yl)methylamine, picH-trpH = 2-carboxypyridine-5-(L-tryptophan)carboxamide (picH-trpMe is the respective tryptophanmethyl ester), pic-OEt = 5-carboethoxypyridine-2-carboxylic acid, were evaluated with rat adipocytes, employing two lipolysis assays (release of glycerol and free fatty acids (FFA)), respectively and a lipogenesis assay (incorporation of glucose into lipids). The IC50 values for the inhibition of lipolysis in the FFA assay vary between 0.41 (+/-0.03) (5) and 21.2 (+/-0.6) mM (2), as compared to 0.81 (+/-0.2) mM for VOSO4.
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| 10. |
- Rahaman, Ahibur, et al.
(författare)
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Chalcogenide-capped triiron clusters [Fe3(CO)9(μ3-E)2], [Fe3(CO)7(μ3-CO)(μ3-E)(μ-dppm)] and [Fe3(CO)7(μ3-E)2(μ-dppm)] (E = S, Se) as proton-reduction catalysts
- 2019
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Ingår i: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X. ; 880, s. 213-222
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Tidskriftsartikel (refereegranskat)abstract
- Chalcogenide-capped triiron clusters [Fe3(CO)7(μ3-CO)(μ3-E)(μ-dppm)] and [Fe3(CO)7(μ3-E)2(μ-dppm)] (E = S, Se) have been examined as proton-reduction catalysts. Protonation studies show that [Fe3(CO)9(μ3-E)2] are unaffected by strong acids. Mono-capped [Fe3(CO)7(μ3-CO)(μ3-E)(μ-dppm)] react with HBF4.Et2O but changes in IR spectra are attributed to BF3 binding to the face-capping carbonyl, while bicapped [Fe3(CO)7(μ3-E)2(μ-dppm)] are protonated but in a process that is not catalytically important. DFT calculations are presented to support these protonation studies. Cyclic voltammetry shows that [Fe3(CO)9(μ3-Se)2] exhibits two reduction waves, and upon addition of strong acids, proton-reduction occurs at a range of potentials. Mono-chalcogenide clusters [Fe3(CO)7(μ3-CO)(μ3-E)(μ-dppm)] (E = S, Se) exhibit proton-reduction at ca. -1.85 (E = S) and -1.62 V (E = Se) in the presence of p-toluene sulfonic acid (p-TsOH). Bicapped [Fe3(CO)7(μ3-E)2(μ-dppm)] undergo quasi-reversible reductions at -1.55 (E = S) and -1.45 V (E = Se) and reduce p-TsOH to hydrogen but protonated species do not appear to be catalytically important. Current uptake is seen at the first reduction potential in each case, showing that [Fe3(CO)7(μ3-E)2(μ-dppm)]- are catalytically active but a far greater response is seen at ca. -1.9 V being tentatively associated with reduction of [H2Fe3(CO)7(μ3-E)2(μ-dppm)]+. In general, selenide clusters are reduced at slightly lower potentials than sulfide analogues and show slightly higher current uptake under comparable conditions.
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