Search results for "Unpaired electron"
showing 10 items of 60 documents
2,2’Bipyrimidine: A Useful Tool in Designing Polynuclear Complexes of Controlled Nuclearity
1996
The versatility of a simple ligand such as 2,2’-bipyrimidine (bpym) which can adopt chelating and bis(chelating) coordination modes facilitates the preparation of both mononuclear and polynuclear complexes whose nuclearity can be controlled by playing with the metal to bpym molar ratio, the nature of the counterion and the presence of additional ligands. In this work, we summarize our results dealing with the preparation and the structural and magnetic characterization of complexes between first-row transition metal ions and bpym. Examples of orbital reversal and tunable exchange in bpym-containing copper(II) complexes are presented and discussed. The influence of the number of unpaired ele…
Chemical and spectroscopical evidence for an electron‐transfer mechanism in the reaction of arenesulfonyl chlorides with anions
1989
The reaction of amide and amidate anions 2 with p-toluenesulfonyl chloride (1) under different reaction conditions gives rise to the total or partial reduction of the acyl halide to p-toluenesulfinic acid (5) and acylation compounds in variable amounts depending on the crowding at the anionic center. This indicates that a Single-Electron Transfer (SET) mechanism is involved in the reactions of 1 with anions. Unpaired electron species are detected by ESR in the course of the reactions.
Organic/inorganic molecular conductors based upon perylene and Lindquist-type polyoxometalates
2001
The preparation, structures and physical properties of the organic/inorganic radical salts based upon perylene (per) and Lindquist type polyoxometalates (POMs) are reported. Three new hybrid salts have been prepared: (per)5[Mo6O19] (1), (per)5[W6O19] (2), and (per)5[VW5O19] (3). Only structures 1 (P, Z = 2) and 3 (P, Z = 2) were fully determined as compound 2 was found to have unit cell parameters practically identical to 1 and, therefore, is considered isostructural with the latter. The structures consist of interpenetrated organic and mixed organic/inorganic layers in the ac plane alternating along the a direction. The organic layers present a novel packing mode of the perylene molecules …
Copper(II) complexes with sulfonamides derived from 2-picolylamine and their use as chemical nucleases
2006
Reaction between 2-picolylamine (2-aminomethylpyridine) with 2-mesitylenesulfonyl and 4- tert -butylbenzene sulfonyl chlorides leads to the formation of 2,4,6-trimethyl- N -[pyridin-2-ilmethyl]benzenesulfonamide (Hpmesa) and 4-ter-butyl- N -[pyridin-2-ilmethyl]benzenesulfonamide (Hptbsa). These compounds react with Cu(II) salts to yield coordination compounds with CuL 2 stoichiometry. The immediate environment of the metal ion is a highly distorted tetrahedron, the sulfonamide ligands acting in a bidentate fashion. Compound Hpmesa crystallizes in monoclinic space group P 2 1 /c (number 14), with Z = 4; complex [Cu(pmesa) 2 ] crystallizes in monoclinic space group P 1 ¯ (number 2), with Z …
Polyradikale mit verdazyl-gruppen
1968
Um Polyradikale mit Verdazylgruppen zu gewinnen, wurden verschiedene Wege erprobt. Die Methylierung von Polyacrolein-formazan fuhrte nicht zum Ziel. Herstellung und Eigenschaften von 1.5-Diphenyl-3-(p-vinylphenyl)-verdazyl werden beschrieben; eine radikalische Polymerisation dieser Verbindung war nicht moglich. Ausgehend von Poly-p-vinylbenzaldehyd gelang es aber, durch polymeranaloge Umsetzungen Polymere mit Verdazylgruppen darzustellen. Diese Polyradikale enthalten in jedem zweiten Grundbaustein ein ungepaartes Elektron. For the synthesis of polymeric verdazyles different routes were investigated. Methylation of poly(acroleinformazanes) was not successful. Synthesis and properties of 1.5-…
Hexanuclear copper(ii) cage with {Cu3O⋯H⋯OCu3} core supported by a dicompartmental oxime ligand with m-xylyl spacer: synthesis, molecular structure a…
2010
A new dicompartmental dioxime ligand (H(2)L) with m-xylyl spacer between the donor sites has been synthesised by Schiff-base condensation of α,α'-diamino-m-xylene and diacetyl monooxime. The ligand reacts with copper(ii) salts giving rise to hexanuclear tricationic copper(II) cage complexes [Cu(II)(6)(μ(3)-O···H···O-μ(3))L(3)(H(2)O)(6)]X(3) (X = BF(4), 1a; X = ClO(4), 1b). The complexes have been characterised by different analytical and spectroscopic techniques and confirmed the hexanuclear structure even in solution. Single crystal X-ray diffraction studies of both the complexes revealed a very similar core structure with three dicompartmental ligands supporting two triangular Cu(3)O core…
Gas phase behavior of radical cations of perfluoroalkyl-1,2,4-triazines: an experimental and theoretical study
2009
Electron ionization mass spectrometry and low-energy collision-induced decomposition reactions occurring in a tridimensional ion trap, together with density functional theory (DFT) calculations on neutrals, even- and odd-electron cations, have been used to study the gas-phase ion chemistry of a series of perfluoroalkyl-1,2,4-triazines. Loss of oxygen, due to thermal degradation occurring before ionization, likely involving the hydroxylamino group, has been observed. Compounds having a carbonyl group at position 6 of the triazine ring fragment in the source by elimination of NO followed by HF or CO. The decomposition pathways occurring due to CID experiments have shown interesting features d…
Three-dimensional bimetallic octacyanidometalates $[M^{IV}{(\mu-CN)_{4}Mn^{II}(H_{2}O)_2}_2 \cdot 4H_{2}O]_{n}$ (M=Nb,Mo,W) : synthesis, single-cryst…
2008
Abstract We report the synthesis, the single-crystal X-ray crystallographic structures and the magnetic properties of three new isostructural cyanido-bridged networks: [M IV {(μ-CN) 4 Mn II (H 2 O) 2 } 2 ·4H 2 O] n [M IV = Nb IV ( 1 ), Mo IV ( 2 ), W IV ( 3 )]. For compound 1 , the magnetic properties reveal a ferrimagnetic phase below 50 K. In contrast, compounds 2 and 3 show a paramagnetic behaviour with no magnetic ordering down to 2 K. The only electronic difference between the two kinds of compounds is the presence of two paired electrons on Mo IV ( 2 ) and W IV ( 3 ) (d 2 electronic configuration, S = 0) with no possible exchange interactions with Mn II ions (d 5 electronic configur…
A magnetic look into the protecting layer of Au25 clusters
2016
The field of molecular metal clusters protected by organothiolates is experiencing a very rapid growth. So far, however, a clear understanding of the fine interactions between the cluster core and the capping monolayer has remained elusive, despite the importance of the latter in interfacing the former to the surrounding medium. Here, we describe a very sensitive methodology that enables comprehensive assessment of these interactions. Pulse electron nuclear double resonance (ENDOR) was employed to study the interaction of the unpaired electron with the protons of the alkanethiolate ligands in four structurally related paramagnetic Au25(SR)0 18 clusters (R ¼ ethyl, propyl, butyl, 2-methylpro…
An experimental and theoretical study of a heptacoordinated tungsten(VI) complex of a noninnocent phenylenediamine bis(phenolate) ligand
2018
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 ox…