Search results for "cyanides"
showing 10 items of 30 documents
PdII-mediated integration of isocyanides and azide ions might proceed via formal 1,3-dipolar cycloaddition between RNC ligands and uncomplexed azide
2016
Reaction between equimolar amounts of trans-[PdCl(PPh3)2(CNR)][BF4] (R = t-Bu 1, Xyl 2) and diisopropylammonium azide 3 gives the tetrazolate trans-[PdCl(PPh3)2(N4t-Bu)] (67%, 4) or trans-[PdCl(PPh3)2(N4Xyl)] (72%, 5) complexes. 4 and 5 were characterized by elemental analyses (C, H, N), HRESI+-MS, 1H and 13C{1H} NMR spectroscopies. In addition, the structure of 4 was elucidated by a single-crystal X-ray diffraction. DFT calculations showed that the mechanism for the formal cycloaddition (CA) of N3− to trans-[PdCl(PH3)2(CNMe)]+ is stepwise. The process is both kinetically and thermodynamically favorable and occurs via the formation of an acyclic NNNCN-intermediate. The second step of the fo…
Pressure-induced magnetic switching and linkage isomerism in K0.4Fe4[Cr(CN)6]2.8 x 16 H2O: X-ray absorption and magnetic circular dichroism studies.
2008
The effect of applied pressure on the magnetic properties of the Prussian blue analogue K0.4Fe4[Cr(CN)6]2.8 x 16 H2O (1) has been analyzed by dc and ac magnetic susceptibility measurements. Under ambient conditions, 1 orders ferromagnetically at a critical temperature (T(C)) of 18.5 K. Under application of pressure in the 0-1200 MPa range, the magnetization of the material decreases and its critical temperature shifts to lower temperatures, reaching T(C) = 7.5 K at 1200 MPa. Pressure-dependent Raman and Mossbauer spectroscopy measurements show that this striking behavior is due to the isomerization of some Cr(III)-C[triple bond]N-Fe(II) linkages to the Cr(III)-N[triple bond]C-Fe(II) form. A…
Detection of mitochondrial electron chain carrier redox status by transhepatic light intensity during rat liver reperfusion.
2003
The aim of the study was to investigate mitochondrial electron transfer during rat liver reperfusion after cold storage and hypothermic machine perfusion. Livers from male Brown Norway rats were preserved (UW) for 10h either by cold storage (CS) or by hypothermic oxygenated perfusion extracorporal (HOPE). Transhepatic photometric analysis allowed determination of the redox status of mitochondrial cytochromes during preservation, rewarming and reperfusion. Mitochondrial electron chain carriers were inhibited at different sites with rotenone and cyanide in some experiments. reversed transcriptional polymerase chain reaction (RT-PCR) was performed after reperfusion concerning transcription of …
Exchange coupling across the cyanide bridge: structural and DFT interpretation of the magnetic properties of a binuclear chromium(III) complex.
2006
The reaction of [Cr(CN)6]3− with a mixture of trans-[Cr(cyclam)(OH)2]Cl, [Cr(cyclam)(OH)Cl]Cl and [Cr(cyclam)Cl2]Cl affords the cyanide bridged dimer, trans-[HO–Cr(cyclam)–NC–Cr(CN)5]−. The tetraphenylphosphonium salt of the anion crystallizes in space group P21/n and shows a bent arrangement of the Cr1–CN–Cr2 unit with the Cr1–CN bond angle at 166.9° and CN–Cr2 at 160.32°. The Cr2–O bond, trans to the hexacyanide fragment, is very short at 1.902 A. Two dimers are held together by two hydrogen bonds connecting the Cr2–OH group of each dimer with one of the NH groups of the cyclam ligand of an adjacent molecule, leading to an almost linear configuration. These dimers of dimers get packed par…
Pairing energy effects in cyanide complexes of CpCrIII
1999
International audience; The steric and electronic factors responsible for the reactivity differences between CN and Cl complexes of CpCrIII were examined by DFT/B3LYP computational techniques. The energy difference between quadruplet and doublet [CpCr(CN)2(PH3)], ΔED–Q, was calculated to be 21.2 kcal mol−1 with the LanL2DZ basis set. Although the high-spin configuration is still the ground state for the cyanide complex, the energy gap is 8.7 kcal mol−1 less than that found for the corresponding chloride species. The difference between quadruplet [CpCr(CN)2(PH3)] and doublet [CpCr(CN)2(PH3)2] less free PH3, ΔECr–P, is also smaller than for the Cl system. The components of ΔECr–P for CN and C…
Diastereoselective Insertion of Isocyanide into the Alkyl−Metal Bond of Methylbenz[ e ]indenyl ansa ‐Zirconocene Complexes
2004
Alkylation of ansa-zirconocene [Zr{(η5-C5H5)SiMe2(MBI)}Cl2] (MBI = η5-2-Me−C13H7) with MgRCl gave the dimethyl complex [Zr{(η5-C5H5)SiMe2(MBI)}Me2], but unresolvable mixtures containing mono-alkylated compounds were obtained when bulkier alkyls were used. However pure dialkyl complexes [Zr{(η5-C5H5)SiMe2(MBI)}R2] (R = CH2Ph, CH2SiMe3) were easily obtained using K(CH2Ph) and Li(CH2SiMe3) as alkylating agents. Diastereoselective insertion into the MBI-unprotected Zr−R bond was observed when all of these dialkyl complexes were treated with 2,6-xylyl isocyanide to give the iminoacyl compounds [Zr{(η5-C5H5)SiMe2(MBI)}R{CR[η2-N-(2,6-xylyl)]}] (R = Me, CH2Ph, CH2SiMe3). All of the new complexes we…
Spin-Crossover and Liquid Crystal Properties in 2D Cyanide-Bridged FeII−MI/II Metalorganic Frameworks
2010
Novel two-dimensional heterometallic Fe(II)-M(Ni(II), Pd(II), Pt(II), Ag(I), and Au(I)) cyanide-bridged metalorganic frameworks exhibiting spin-crossover and liquid crystal properties, formulated as {FeL(2)[M(I/II)(CN)(x)](y)}·sH(2)O, where L are the ligands 4-(4-alkoxyphenyl)pyridine, 4-(3,4-dialkoxyphenyl)pyridine, and 4-(3,4,5-trisalkoxyphenyl)pyridine, have been synthesized and characterized. The physical characterization has been carried out by means of EXAFS, X-ray powder diffraction, magnetic susceptibility, differential scanning measurements, and Mössbauer spectroscopy. The 2D Fe(II) metallomesogens undergo incomplete and continuous thermally induced spin transition at T(1/2) ≈ 170 …
Thermal-,Pressure-, and Light-Induced Spin Transition in Novel Cyanide-Bridged FeII-AgI Bimetallic Compounds with Three-Dimensional Interpenetrating …
2002
[EN] Low-spin, high-spin and spin-transition behaviours have been observed for the doubly interpenetrating three-dimensional bimetallic compounds {Fe-II(pz)[Ag(CN)(2)](2)}.pz (pz= pyrazine), {Fe-II(4,4'-bipy)(2)[Ag(CN)(2)](2)} (4,4'-bipy-4,4'-bipyridine), and {Fe-II-(bpe)(2)[Ag(CN)(2)](2)} (bpe = bispyridylethylene), respectively. The single crystals of the bpe derivative undergo a spin transition with a large hysteresis loop at about 95 K. After several warming and cooling cycles, the single crystals become a microcrystalline powder with 50% spin transition. Influence of pressure- as well as light-induced excited spin-state trapping (LIESST) on the thermal 50% spin transition of the microc…
High-dimensional mixed-valence copper cyanide complexes: Syntheses, structural characterizations and magnetism
2009
International audience; Reactions of CuCl 2 with different CN complexes in presence of a neutral ancillary ligand lead to two novel mixed-valence Cu complexes [Cu II (bpy)Cu I (CN) 3 ] n , 1 (bpy=2,2′-bipyridine) and {[Cu II (tn) 2 ][Cu I 4 (CN) 6 ]} n 2 (tn=1,3-diaminopropane). For compound 1, the asymmetric unit involves two Cu ions Cu1 and Cu2 (Cu I and Cu II centres, respectively) which strongly differ in their environments. The Cu1 ion presents a CuC 4 pseudo-tetrahedral geometry, while the Cu2 ion presents a CuN 5 slightly distorted square-pyramidal geometry. The extended structure of 1 is generated by three cyano ligands which differ in their coordination modes. One CN group has a μ …
Magnetic resonance imaging of the migration of neuronal precursors generated in the adult rodent brain
2006
Neural progenitor cells (NPCs) reside within the subventricular zone (SVZ) in rodents. These NPCs give rise to neural precursors in adults that migrate to the olfactory bulb (OB) along a well-defined pathway, the rostral migratory stream (RMS). Here we demonstrate that these NPCs can be labeled, in vivo, in adult rats with fluorescent, micron-sized iron oxide particles (MPIOs), and that magnetic resonance imaging (MRI) can detect migrating neural precursors carrying MPIOs along the RMS to the OB. Immunohistochemistry and electron microscopy indicated that particles were inside GFAP(+) neural progenitor cells in the SVZ, migrating PSA-NCAM(+) and Doublecortin(+) neural precursors within the …