The complexes (η5-C5R5)MoO2Cl (R = H, CH3 (Me), CH2Ph (Bz)) are readily prepared from the parent carbonyls (η5-C5R5)Mo(CO)3Cl upon reaction with t-BuOOH (TBHP) in n-decane. The compounds are ...characterized by vibrational spectroscopy, 1H, 13C, and 95Mo NMR spectroscopy, and elementary analysis and are compared to their (η5-C5R5)ReO3 homologues. The Mo−C5R5 force constants have been determined. (η5-C5Bz5)MoO2Cl can be stored and handled at room temperature without decomposition, in contrast to the more temperature sensitive Cp (R = H) and Cp* (R = Me) analogues. The (η5-C5R5)MoO2Cl complexes catalyze the epoxidation of cyclooctene, styrene, and 1-octene with TBHP as oxidizing agent. The highest activity is found for (η5-C5Bz5)MoO2Cl: TOF 21000 mol/(mol × h) for cyclooctene in CH2Cl2 at 55 °C with a ratio catalyst:substrate:TBHP = 0.0001:1:2.5. This activity even surpasses that of the well-known MeReO3/H2O2 system. The stable parent carbonyls (η5-C5R5)Mo(CO)3Cl can be used as catalyst precursors since they are transformed into (η5-C5R5)MoO2Cl under the operating catalytic conditions.
The temperature−composition phase diagrams of 40 binary mixtures composed of a haloalkane dissolved in either 1-ethyl-3-methylimidazolium ethylsulfate or 1-ethyl-3-methylimidazolium ethylsulfonate ...were measured from ambient temperature to the boiling point temperature of the solute. The coexistence curves corresponding to liquid−liquid equilibria (LLE) boundaries were visually determined and the experimental results have been correlated using either the nonrandom two-liquid (NRTL) model or a set of empirical equations capable of describing the corresponding upper critical solution temperatures (UCSTs) loci. The different types of LLE behavior were discussed in terms of the type of ionic liquid solvent, the alkyl-chain length of the solute, and the type and pattern of halogen substitution present in the haloalkane. Auxiliary simulation data (obtained by ab initio or by molecular dynamics methods) were used to corroborate some of the experimental findings. Also, they correlate in a semiquantitative way the observed LLE behavior with the dipole moments of the different solutes.
The following information was missing from the Funding section: "The article processing charge was funded by the German Research Foundation (DFG) and the Albert Ludwigs University Freiburg in the ...funding programme "Open Access Publishing". (2013) Correction: Carbon Monoxide Abrogates Ischemic Insult to Neuronal Cells via the Soluble Guanylate Cyclase-cGMP Pathway.
The dissolution of the indenyl (Ind) complex {(η5‐Ind)Mo(CO)2(μ‐Cl)}2 (1) in N,N′‐dimethylformamide (DMF) gives the ring‐slipped complex (η3‐Ind)Mo(CO)2Cl(DMF)2 (2). The aerial oxidation of 2 leads ...to the formation of the dinuclear oxomolybdenum(V) chloride Mo2O2(DMF)4(μ‐O)2Cl2 (3). The structures of 2 and 3·DMF have been determined by single‐crystal X‐ray diffraction. Compounds 1 and 3 were examined as promoters of phosphoester bond hydrolysis in para‐nitrophenylphosphate (pNPP), which was used as a model substrate. The reactions were performed in aqueous solution at 55 °C and followed by 1H NMR spectroscopy. For assays performed with 30–100 mol‐% of 1 or 3 relative to pNPP, both compounds promote the production of para‐nitrophenol (pNPh) from pNPP. Compound 3 is especially active in promoting the hydrolytic cleavage of the phosphoester bond (t1/2 < 80 min).
The dissolution of {(η5‐Ind)Mo(CO)2(μ‐Cl)}2 (Ind = indenyl) in N,N‐dimethylformamide (DMF) results in the formation of (η3‐Ind)Mo(CO)2Cl(DMF)2, the aerial oxidation of which leads to Mo2O2(DMF)4(μ‐O)2Cl2. {(η5‐Ind)Mo(CO)2(μ‐Cl)}2 and Mo2O2(DMF)4(μ‐O)2Cl2 are examined as promoters of phosphoester bond hydrolysis of para‐nitrophenylphosphate (pNPP) in aqueous solution at 55 °C.
The endogenously produced gaseous molecule carbon monoxide is able to promote organ protection after ischemia-reperfusion injuries (IRI). The impact of carbon monoxide releasing molecules (CORM) ...regarding inflammation in neuronal tissues has not been studied in detail. In this investigation, we aimed to analyze the effects of the CORM ALF-186 on neuro-inflammation and hypothesized that the soluble guanylate cyclase (sGC) is playing a decisive role.
Retinal ischemia-reperfusion injury was performed for 60 min in Sprague-Dawley rats. Thereafter, the CORM ALF-186 (10 mg/kg) in the presence or absence of the sGC inhibitor ODQ was injected via a tail vein. Retinal tissue was harvested 24 h later to analyze mRNA or protein expression of sGC-β1 subunit, transcription factors NF-κB and CREB, the inflammatory cytokines TNF-α and IL-6, as well as the heat shock proteins (HSP) HSP-70 and HSP-90. Immunohistochemistry was performed on frozen sections of the retina. The overall neuroprotective effect of ALF-186 was assessed by counting fluorogold-pre-labeled retinal ganglion cells (RGC) 7 days after IRI.
Ischemia-reperfusion mediated loss of vital RGC was attenuated by the administration of ALF-186 after injury. ALF-186 treatment after IRI induced sGC-ß
leading to a decreased NF-κB and CREB phosphorylation. Consecutively, ALF-186 mitigated IRI induced TNF-α and IL-6 expression in the retina and in the rats' serum. Moreover, ALF-186 attenuated heat shock protein 70 (Hsp-70) while increasing Hsp-90. The sGC-inhibitor ODQ attenuated the anti-inflammatory effects of ALF-186 and increased retinal loss of ganglion cells. These results were confirmed by immunohistochemistry.
The CORM ALF-186 protected RGC from IRI induced loss. Furthermore, ALF-186 reduced IRI mediated neuroinflammation in the retina and in the serum by activating sGC. Inhibition of sGC stopped the beneficial and protective effects of ALF-186. ALF-186 may present a promising therapeutic alternative in treating inflammation after neuronal IRI.
The Nature of the Indenyl Effect Calhorda, Maria José; Romão, Carlos C.; Veiros, Luis F.
Chemistry : a European journal,
02/2002, Letnik:
8, Številka:
4
Journal Article
Recenzirano
The η5‐to‐η3 coordination shift of cyclopentadienyl (Cp=C5H5−) and indenyl (Ind=C9H7−) ligands in molybdenocene complexes, (η5‐Cp′)(η5‐Cp)Mo(CO)22+ (Cp′=Cp or Ind), driven by a two‐electron reduction ...of those species, was studied and compared by means of molecular orbital calculations (B3LYP HF/DFT hybrid functional, DZP basis sets). The results obtained, in terms of optimized geometries, relative energies, and bond analysis parameters, compare well with the experimental data, and verify the well‐known indenyl effect, that is, a significantly more facile η5‐to‐η3 rearrangement for the indenyl ligand when compared to cyclopentadienyl. However, the study of the folding of free Cp and Ind, combined with the (η5/3‐Cp′)−M bond analysis, shows that the observed difference is not the result of an intrinsic characteristic of the indenyl ligand, such as the traditionally accepted aromaticity gain in the benzene ring formed in η3‐Ind complexes. Instead, it is directly related to the Cp′−M bond strength. While the difference in the energy required to fold the two free ligands is negligible (≤1 kcal mol−1 for folding angles up to 20°), the (η5‐Cp)−M bond is stronger than that of (η5‐Ind)−M; however, the opposite situation is found for the η3 coordination mode. The net result, for Cp′=Ind, is a destabilization of the η5 complexes and a stabilization of the η3 intermediates or transition states yielding smaller activation energies and faster reaction rates for processes in which that is the rate‐determining step.
A new interpretation for the indenyl effect, which is based on based on the stability of both the η5 reactants and the η3 intermediates (see plot) is derived from a density funtional theory/B3LYP study of the two‐electron reduction of (η5‐Cp′)(η5‐Cp)Mo(CO)22+ (Cp′ = Cp, Ind).
A series of cis-Mo(CO)4(amine)2 complexes (NR3 = morpholine 1; 4-Me–piperazine, 2; H2NCH2CH2NH2, 3; H2NCH2CH2–morpholine (4) R2NCH2CH2–piperazine–4-Me (R = H, 5); R = Me, 6); Me2NCH2CH2NMe2, 7) was ...prepared in good yields, in a one-step microwave-assisted synthesis. The X-ray diffraction structures of the complexes 4, 5 and 6 are reported. The stability of the complexes 1–7 in aqueous, aerobic media was studied by UV–Vis spectrophotometry, RP-HPLC and gas chromatography at several pH values. Stability beyond 1 h requires bidentate ligands with at least one tertiary amine ligand and increases in the order 4 < 5 < 6. Stability is approximately the same at pH 7.5 and pH 3.9 for 5 and 6 in solutions acidified with HCl. Acidification with CF3COOH induces decomposition. The order of CO transfer rate to deoxy-Mb and haemoglobin in whole blood is 1 > 2 > 3 > 4 > 5 > 6 >> 7, but it is much faster to whole blood. The haemolytic index of some compounds increases in a similar order: 1 < 2 < 5 < 6; with the exception of 1, the complexes are not toxic to RAW264.7 cells up to a concentration of 100 μM.
The biological stability and compatibility of the CORM scaffold Mo(CO)4(NR3)2 can be tuned by installing increased alkyl substitution in the inner sphere and distal charged functions in the outer sphere. Display omitted
•Mo(CO)4(NR3)2 complexes can be tuned for stability and solubility in aerobic, biological media and blood.•Such complexes are made by one-step microwave-assisted synthesis.•Stability to air, water and blood requires bidentate, tertiary amines with distal charged functions.•Cytotoxicity is negligible for stable, soluble complexes.•Haemolytic Index decreases with increasing stability and solubility.
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