Showing papers in "European Journal of Inorganic Chemistry in 2018"

Metal-to-Metal Electron Transfer : a powerful tool for the design of switchable coordination compounds

Abstract: Since the report of photomagnetic effects in Prussian blue Fe/Co networks 20 years ago by the japanese group of Hashimoto, a substantial family of molecular analogs have been obtained and characterized. These compounds offer a unique opportunity to follow metal-to-metal electron transfer by investigating their structural, spectroscopic, electrochemical and magnetic properties. We propose an overview of recent results in order to highlight the common features of these coordination compounds, as well as the differences, with the well-known class of photomagnetic coordination compounds based on spin crossover.

N-Heterocyclic Carbene-Phosphinidene Adducts: Synthesis, Properties, and Applications

Abstract: Syntheses, properties, and reactivity of N-heterocyclic carbene-phosphinidene adducts are reviewed. These adducts, formally built by combining a phosphinidene with a carbene, are characterized by high nucleophilicity at the phosphorus atom. The main types of reactivity these adducts exhibit are: Lewis-base reactivity towards main group and organic compounds as well as transition-metal complexes, substitution reactions at the phosphorus atom with main group compounds and transition-metal complexes, and phosphinidene transfer reactions resulting in C-P bond cleavage. These differ substantially from the classic phosphaalkenes.

Mechanistic Considerations on Homogeneously Catalyzed Formic Acid Dehydrogenation

Abstract: This work was supported by the Spanish Ministry of Economy and Competitiveness [“Ramon y Cajal” programme (M. I.)] and the DGA/FSE-E07. The support from the KFUPM-University of Zaragoza research agreement and the Centre of Research Excellence in Petroleum Refining & KFUPM is gratefully acknowledged

Synthesis, Transformation, Catalysis, and Gas Sorption Investigations on the Bismuth Metal–Organic Framework CAU-17

Abstract: Very few microporous bismuth metal-organic frameworks have been discovered to date. Of these, no detailed experimental characterization of the synthesis and properties have been reported until now for the only one which can be prepared from inexpensive starting materials: CAU-17 [Bi(BTC)(H2O)], with H3BTC = trimesic acid. In-situ powder X-ray diffraction during solvothermal synthesis of CAU-17 revealed that it crystallizes rapidly within 2 minutes, and if the reaction is not stopped, the MOF transforms into a nonporous dense purely inorganic material within one hour, revealing that CAU-17 is a crystalline intermediate phase. Synthesis scale-up employing more concentrated reaction mixtures resulted in another Bi trimesate of composition [Bi(HBTC)(NO3)(MeOH)]MeOH, which structurally decomposes upon storage under ambient conditions. Sorption experiments showed that CAU-17 is microporous with a BET surface area of 530 m(2)/g. As a potential greenhouse gas sorbent, CAU-17 showed high SF6/N-2 and CO2/N-2 selectivity > 31 and 29, respectively. Furthermore, the catalytic activity of CAU-17 was studied in the regioselective ring-opening of styrene oxide by methanol to obtain 2-methoxy-2-phenylethanol, thus demonstrating the existence of coordinatively unsaturated sites in the crystal structure of CAU-17.

Design of Magnetic Coordination Polymers Built from Polyoxalamide Ligands: A Thirty Year Story

Abstract: The aim of this review is to pay tribute to the attractive legacy of O. Kahn. Kahn's credo was to synthesize magnetic compounds with predictable structure and magnetic properties. This is illustrated herein on results obtained by Kahn's group during his Orsay period thirty years ago but also on the basis of our recent results on the synthesis of coordination polymers with oxamate ligands. The first part of this review is devoted to a short description of the necessary knowledge in physics and theoretical chemistry that Kahn and his group have used to select oxamate ligands, the complex-as-ligand strategy and the synthesis of heterobimetallic systems. Then, we describe the strategies we have later used to obtain the desired target compounds. The use of complexes as building-blocks, associated to a control of the metal ions chirality and stoichiometry, allowed us to obtain coordination polymers with predictable dimensionality. For the synthesis of Single-Chain Magnets we show that the ligand chemical flexibility makes the isolation of the chains in the solid and the occurence of slow magnetic relaxation possible. For 1D and 2D Molecule-Based Magnets the magnetic ordering strongly depends on the interchain or interplane interactions which are difficult to control. Again the flexibility of the oxamate ligands allowed their strengthening in the solid sate, yielding MBMs with critical temperatures up to 30K. We will also present our results on 3D coordination polymers, particularly on the porous magnets displaying large octagonal channels. This family of porous MBMs possess outstanding chemical properties, such as post-synthetic transformation in the solid state. Finally, we will also show that oxamate ligands allows the design of multifunctional materials, as in the case of the first chiral SCM. Overall, the results presented in this review show the impressive potential the oxamate ligands have for the design of coordination

Zinc Ferrite Anchored Multiwalled Carbon Nanotubes for High‐Performance Supercapacitor Applications

Abstract: Recently, thin-film supercapacitors have received much interest because they can achieve both high energy densities and high power densities, which make them suitable for practical applications. Here, thin films consisting of zinc ferrite (ZnFe2O4) anchored on multiwalled carbon nanotubes (CNT) were prepared through a simple and inexpensive successive ionic layer adsorption and reaction (SILAR) method. This method has the advantage of direct electrode formation without the use of any binder. The synergy of the composite electrode (ZnFe2O4-CNT) yields a high specific capacity of 217 mAhg(-1) at 5 mVs(-1), which is realized by contributions from the inner and outer active surfaces of the hybrid ZnFe2O4-CNT electrode. Furthermore, a solid-state symmetric device exhibits a highest specific energy of 12.80 Whkg(-1) and a specific power of 377.86 Wkg(-1), which clearly demonstrates that our hybrid ZnFe2O4-CNT electrode is promising and innovative for energy-storage applications.

Regioselective Nucleophilic Additions to Diiron Carbonyl Complexes Containing a Bridging Aminocarbyne Ligand: A Synthetic, Crystallographic and DFT Study

Abstract: Diiron µ-aminocarbyne compounds, 1a–e, are prepared in two steps from Fe2Cp2(CO)4, negating the need for difficult purification procedures of intermediate species; they are efficiently isolated by alumina chromatography. Minor amounts of µ-aminocarbyne aryl isocyanide compounds, 2a–c, are obtained as side products. The structures of the cations in 1a,c,e are calculated using DFT; the carbyne carbon is generally predicted to be the thermodynamic site of hydride addition, in agreement with a previous experimental finding concerning 1a. Accordingly, the reaction of 1e with NaBH4 affords a bridging aminocarbene complex, 4, in 85 % yield. Otherwise, the reaction of 1c with NaBH4 yields the aminocarbyne–cyclopentadiene derivative 3 (70 %), presumably as a consequence of the steric protection exerted by the xylyl–methyl groups towards the carbyne moiety. The sequential treatment of 1a,c with Li2CuCNMe2 and MeSO3CF3 affords 5a,b, comprising both aminocarbyne and alkoxycarbene ligands. In accordance with DFT calculations, the alkoxycarbene moiety in 5a is the most favourable site for nucleophilic attack. Thus, the reactions of 5a with NH2R (R = Et, iPr) and NBu4CN, respectively, give the aminocarbyne/aminocarbene complexes, 6a,b, and the aminocarbyne-α-cyanoalkyl 7. All the products are fully characterized by spectroscopic and analytical methods; moreover, the structures of 1a, 1d, 6a and 7 are elucidated by single-crystal X-ray diffraction studies.

Application of [Co(Corrole)]- Complexes in Ring-Closing C-H Amination of Aliphatic Azides via Nitrene Radical Intermediates

Abstract: The synthesis, characterisation and application of anionic [CoII(Cor)]– (Cor = corrole) metalloradicals in the ring‐closing C–H amination of an aliphatic azide in the presence of Boc2O (Boc = tert‐butyloxycarbonyl) to give the corresponding Boc‐protected N‐heterocyclic product tert‐butyl 2‐phenylpyrrolidine‐1‐carboxylate are reported. This is the first example of the use of metalloradical cobalt(II) corrole complexes in nitrene‐transfer reactions. On the basis of DFT calculations, the reaction is proposed to proceed via discrete open‐shell nitrene radical intermediates bearing most of their spin density at the nitrene nitrogen atom. The [CoII(Cor)]– complexes are substantially faster catalysts than the corresponding neutral [CoII(porphyrin)] complexes when applied in the same ring‐closing C–H amination reaction under identical reaction conditions. Increasing the electron density at cobalt(II) therefore has a positive influence on the reaction rate.

In situ Carbothermal Synthesis of Nanoscale Zero-Valent Iron Functionalized Porous Carbon from Metal–Organic Frameworks for Efficient Detoxification of Chromium(VI)

Abstract: Owing to the high toxicity of CrVI species to human health and the ecosystem, much attention has been paid to the development of efficient adsorbents for CrVI Herein, MIL-100(Fe) was successfully utilized as a precursor for the carbothermal reductive synthesis of nanoscale zero-valent iron functionalized porous carbon (nZVI@C) for the effective removal of CrVI The organic ligands in MIL-100(Fe) were transformed into a porous carbon matrix, whereas the Fe–O clusters were reduced in situ to nZVI owing to the strong reducibility of pyrolytic carbon Additionally, the nZVI was distributed uniformly in the carbon support with a high loading and controllable particle size Highly toxic CrVI species were efficiently degraded into less toxic CrIII species at the nZVI reductive sites, and then the CrIII species precipitated as (CrxFe1–x)(OH)3 in the porous hybrids The CrVI adsorption capacity of the developed nZVI@C reached 206 mg g–1 under optimal conditions Furthermore, the excellent magnetic performance of nZVI@C makes it convenient for CrVI remediation through simple magnetic separation These outstanding characteristics indicate the promising potential of the developed material as an adsorbent for the efficient removal of CrVI from industrial wastewater