Oxyfunctionalization of Non-Natural Targets by Dioxiranes. 3. Efficient Oxidation of Buckminsterfullerene C₆₀ with Methyl(trifluoromethyl)dioxirane

By employing methyl(trifluoromethyl)dioxirane (1b), the stepwise oxyfunctionalization of C60 can be carried out with high conversions (>90%) under mild conditions (0 °C); the products have been compared with those produced by the oxidation of C60 with m-chloroperoxybenzoic acid. Along with the previously characterized oxide C60O, a wider set of higher oxidation products is obtained by using 1b; among these, regioisomeric dioxides C60O2 are isolated in good overall yield (40%). One of the dioxides is predominant (yield 23%), corresponding to a Cs-symmetry dioxide previously well characterized and presenting the epoxide functionalities in close proximity over the 6:6 ring junctions. The oxidation with dioxirane 1b also produces sufficient quantities of trioxides, so that mixtures of C60O3 regioisomers can be isolated. The main trioxide fraction was found amenable to spectroscopic characterization; the 13C NMR spectra indicates that the sample consists of two possible regioisomers, one having Cs, and the other C2 symmetry. In both, the three epoxide rings are assembled over 6:6 ring junctions and in close proximity to each other; this shows that, in the ensuing sequential O-transfers from the dioxirane to the fullerene framework, the 6:6 carbon−carbon double bonds adjacent to an existing epoxide functionality are more easily oxidized. The whole of the spectroscopic data indicate that the fullerene core remains intact and no rupture of the cage occurs following oxidation at the trioxide level

An iron(II) diamine diketonate molecular complex: synthesis, characterization and application in the CVD of Fe2O3 thin films

<div>Green open access version of the paper:</div><div><div>An iron(II) diamine diketonate molecular complex: synthesis, characterization and application in the CVD of Fe2O3 thin films</div></div><div><br></div><div>published in:</div><div><div>Inorganica Chimica Acta, 2012, 380, 161–166  </div><div><div>http://dx.doi.org/10.1016/j.ica.2011.10.036</div></div><div>which should be cited to refer to this work</div></div><div><br></div><div>Short non-technical summary of this paper: https://goo.gl/Fpwws7</div><div><br></div><div><div>This contribution was uploaded during the Open Access Week 2016 and is meant to be a little concrete step to put "Open in Action".</div><div><br></div></div

Cu(II) is reduced to Cu(I) without external reductants

Movie showing  the Cu(II)-to-Cu(I) intramolecular reduction in a copper(II) complex.<div><br></div><div>The reaction involves a copper(II) complex, which bears a diamine ligand and a diketonate ligand. The complex is planar and positively charged (+1).  </div><div>Atom colors: Cu=yellow, F=green, O=red, N=blue, C=grey, H=white. The atoms of the diamine C*-H* bond (which breaks homolytically during the reaction) are highlighted as bigger spheres. The oxygen atom O* (which accepts the hydrogen atom H*) is highlighted as a bigger magenta sphere.</div><div><div><br></div><div>Description of the movie:</div><div>- In the first phases of the reduction reaction, the copper complex switches from a square-planar to a twisted-tetrahedral geometry. </div><div>-  An out-of-plane rotation (180 degrees) of the diketonate ligand occurs.</div><div>-  The C*H* bond of the diamine gradually approaches the oxygen atom O* of the diketonate, while becoming increasingly elongated and closer to the metal center. </div><div>- The  C*H*  bond, now fully activated, displaces the diketonate oxygen away from its coordination position.</div><div> Now, the H* is on the fly between the two ligands, and the diamine acts as a polydentate ligand towards the copper center.</div><div> - The binding of H* to the diketonate oxygen O* leads to a beta-diketone enol and to an alpha-dehydrogenated diamine. </div><div>- A six-membered ring is formed through the C terminal of the amine, which is coordinated to the copper center.</div><div>- The neutral diketone ligand  finally leaves the Cu-ring structure. </div><div><br></div><div>At the beginning of the reaction, Cu is in the Cu(II) oxidation state.</div><div>In the transition state, the spin density distribution showed: 1) the formation of a radical moiety, which proved that the C*-H* bond cleavage is homolytic; 2) that the O-H bond formation is accompanied by a simultaneous electron transfer to Cu, which is reduced to Cu(I)</div><div>At the end of the reaction, the oxidation state of copper is Cu(I), as proved by calculations.</div><div><br></div><div>This reaction is described in the article:</div><div>How Does Cu-II Convert into Cu-I: An Unexpected Ring-Mediated Single-Electron Reduction.</div><div><br></div><div>Published in:</div><div>Chem. Eur. J., 17: 10864–10870. </div><div>doi:10.1002/chem.201101551</div></div><div><br></div><div>A green open access version of the paper is available at this link: https://figshare.com/articles/How_Does_Cu_II_Convert_into_Cu_I_/3478880</div><div><br></div><div>Other material can be found at the links below</div

MALDI−TOF Mass Spectrometry in the Study of CO/Aromatic Olefins Terpolymers

MALDI−TOF Mass Spectrometry in the Study of CO/Aromatic Olefins Terpolymer

Cu(II) Reduction without Reductants: Insights from Theory

<p>A topic issue in sustainable technologies is the production of Cu<i>_x</i>O (<i>x</i>=1,2) nanomaterials with tailored composition and properties. They can be fabricated through bottom-up processes that involve unexpected changes in the metal oxidation state and open intriguing challenges on the copper redox chemistry. How Cu^(II) complexes can lead to Cu^(I) species in spite of the absence of any explicit reducing agent is a question only recently answered by investigating the fragmentation of a Cu^(II) precursor for Cu oxide nanostructures by computer simulations and ESI-MS with multiple collisional experiments (ESI/MS<i>n</i>). Here we show that a Cu-promoted CH bond activation leads to reduction of the metal center and formation of a Cu^I-C-NCCN six-membered ring. Such 6-ring moiety is the structural motif for a new family of cyclic Cu^(I) adducts, characterized by a bonding scheme that may shed unprecedented light on high-temperature Cu chemistry. In particular, in this contribution we describe how collisions with hot atoms may activate Cu^(II) species to a configuration prone to the reduction. Besides its relevance for the fabrication of Cu-oxide nanostructures, the hydrogen-abstraction/proton-delivery/electron-gain mechanism of Cu^(II) reduction described herein could be a general property of copper and might help to understand its redox reactivity.</p><p>Poster presented at the 39th International Conference and Expo on Advanced Ceramics and Composites - Daytona Beach (FL) 25-31 Jan 2015</p

Dinuclear Cu(II) Complexes of Isomeric Bis-(3-acetylacetonate)benzene Ligands: Synthesis, Structure, and Magnetic Properties

Highly versatile coordinating ligands are designed and synthesized with two β-diketonate groups linked at the carbon 3 through a phenyl ring. The rigid aromatic spacer is introduced in the molecules to orient the two acetylacetone units along different angles and coordination vectors. The resulting para, meta, and ortho bis-(3-acetylacetonate)­benzene ligands show efficient chelating properties toward Cu­(II) ions. In the presence of 2,2′-bipyridine, they promptly react and yield three dimers, 1, 2, and 3, with the bis-acetylacetonate unit in bridging position between two metal centers. X-ray single crystal diffraction shows that the compounds form supramolecular chains in the solid state because of intermolecular interactions. Each of the dinuclear complexes shows a magnetic behavior which is determined by the combination of structural parameters and spin polarization effects. Notably, the para derivative (1) displays a moderate antiferromagnetic coupling (J = −3.3 cm–1) along a remarkably long Cu···Cu distance (12.30 Å)

Dinuclear Cu(II) Complexes of Isomeric Bis-(3-acetylacetonate)benzene Ligands: Synthesis, Structure, and Magnetic Properties

Highly versatile coordinating ligands are designed and synthesized with two β-diketonate groups linked at the carbon 3 through a phenyl ring. The rigid aromatic spacer is introduced in the molecules to orient the two acetylacetone units along different angles and coordination vectors. The resulting <i>para</i>, <i>meta</i>, and <i>ortho</i> bis-(3-acetylacetonate)­benzene ligands show efficient chelating properties toward Cu­(II) ions. In the presence of 2,2′-bipyridine, they promptly react and yield three dimers, <b>1</b>, <b>2</b>, and <b>3</b>, with the bis-acetylacetonate unit in bridging position between two metal centers. X-ray single crystal diffraction shows that the compounds form supramolecular chains in the solid state because of intermolecular interactions. Each of the dinuclear complexes shows a magnetic behavior which is determined by the combination of structural parameters and spin polarization effects. Notably, the <i>para</i> derivative (<b>1</b>) displays a moderate antiferromagnetic coupling (<i>J</i> = −3.3 cm^–1) along a remarkably long Cu···Cu distance (12.30 Å)

A Cobalt(II) Hexafluoroacetylacetonate Ethylenediamine Complex As a CVD Molecular Source of Cobalt Oxide Nanostructures

An adduct of Co(II) 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate with N,N,N′,N′-tetramethylethylenediamine is synthesized by a simple procedure and, for the first time, thoroughly characterized by several analytical methods in order to elucidate its structure (single-crystal X-ray diffraction), chemical composition (elemental analyses, FT-IR), optical properties (UV−vis absorption spectroscopy), thermal behavior (thermogravimetric analysis and differential scanning calorimetry), and fragmentation pathways (electrospray ionization mass spectrometry and tandem mass spectrometry). The target complex is monomeric with a pseudo-octahedral Co(II) core and presents a clean decomposition pathway and a high volatility at moderate temperatures. Preliminary chemical vapor deposition (CVD) experiments highlight its very promising features as a CVD/atomic layer deposition molecular source for cobalt oxide nanosystems

A Cobalt(II) Hexafluoroacetylacetonate Ethylenediamine Complex As a CVD Molecular Source of Cobalt Oxide Nanostructures

An adduct of Co(II) 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate with N,N,N′,N′-tetramethylethylenediamine is synthesized by a simple procedure and, for the first time, thoroughly characterized by several analytical methods in order to elucidate its structure (single-crystal X-ray diffraction), chemical composition (elemental analyses, FT-IR), optical properties (UV−vis absorption spectroscopy), thermal behavior (thermogravimetric analysis and differential scanning calorimetry), and fragmentation pathways (electrospray ionization mass spectrometry and tandem mass spectrometry). The target complex is monomeric with a pseudo-octahedral Co(II) core and presents a clean decomposition pathway and a high volatility at moderate temperatures. Preliminary chemical vapor deposition (CVD) experiments highlight its very promising features as a CVD/atomic layer deposition molecular source for cobalt oxide nanosystems

A New Class of Antitumor <i>trans</i>-Amine-Amidine-Pt(II) Cationic Complexes: Influence of Chemical Structure and Solvent on in Vitro and in Vivo Tumor Cell Proliferation

The reactions of cyclopropylamine, cyclopentylamine, and cyclohexylamine with trans-[PtCl2(NCMe)2] afforded the bis-cationic complexes trans-[Pt(amine)2(Z-amidine)2]2+[Cl−]2, 1−3. The solution behavior and biological activity have been studied in different solvents (DMSO, water, polyethylene glycol (PEG 400), and polyethylene glycol dimethyl ether (PEG-DME 500)). The biological activity was strongly influenced by the cycloaliphatic amine ring size, with trans-[Pt(NH2CH(CH2)4CH2)2{N(H)C(CH3)N(H)CH(CH2)4CH2}2]2+[Cl−]2 (3) being the most active compound. Complex 3 overcame both cisplatin and MDR resistance, inducing cancer cell death through p53-mediated apoptosis. Alkaline single-cell gel electrophoresis experiments indicated direct DNA damage, reasonably attributable to DNA adducts of trans-[PtCl(amine)(Z-amidine)2][Cl] species, which can evolve to produce disruptive and nonrepairable lesions on DNA, thus leading to the drug-induced programmed cancer cell death. Preliminary in vivo antitumor studies on C57BL mice bearing Lewis lung carcinoma highlighted that complex 3 promoted a significant and dose-dependent tumor growth inhibition without adverse side effects