Search results for "graph"
showing 10 items of 55700 documents
Aza and cyanobridged tripodal dinuclear copper(II) complexes: Electrochemical studies and structural evidence for an original azacyanocarbanion
2014
International audience; The reactivity of the mononuclear [Cu(TMPA)(L)] n+ complex (TMPA: tris(2-methylpyridine) amine, L: CH3CN, H2O) towards two different bridging species (tetracyanoethylene, 4,40-bipyridine) was investigated. The dinuclear complex [(mu-4,40-bipy)Cu-II(TMPA)(2)](CF3SO3)(4) (1) was synthesised and analysed by Xray diffraction (XRD). Magnetic studies revealed that this derivative displays very weak antiferromagnetic interactions between the two metal centres (2J = -0.69 cm(-1)). Solution studies (EPR spectroscopy and voltammetry) evidenced the lability of the bridged neutral bipyridine ligand in acetonitrile. The reaction of TCNE (TCNE: tetracyanoethylene) with the copper(…
Synthesis, crystal structure and magnetic properties of [Co(bpcam)2]ClO4·dmso·H2O, [Co(bpcam)2]2[Co(NCS)4]·dmso·H2O and [Ni(bpcam)2]·H2O [Hbpcam = bi…
2017
The preparation, spectroscopic characterization, structural study and magnetic investigation of three new complexes of formula [Co(bpcam)2]ClO4·dmso·H2O (1), [Co(bpcam)2]2[Co(NCS)4]·dmso·H2O (2) and [Ni(bpcam)2]·H2O (3) [Hbpcam = bis(2-pyrimidylcarbonyl)amide] are reported. Each bpcam group in 1–3 acts as a tridentate ligand being coordinated to the cobalt(III) (1 and 2)/nickel(II) (3) ions through three nitrogen atoms in a mer-arrangement. Six-coordinate cobalt(III) and nickel(II) occur in 1 and 3 respectively, whereas six-coordinate cobalt(III) and four-coordinate cobalt(II) coexist in 2. Cyclic voltammetry of 1 in acetonitrile shows the occurrence of one quasi reversible CoIII ↔ CoII pro…
Halogen bonds in 2,5-dihalopyridine-copper(II) chloride complexes
2018
Ten coordination complexes obtained through a facile reaction between 2,5-dihalopyridines and copper(II) chloride (CuCl2) are characterized using single crystal X-ray diffraction. Two series of dihalopyridine complexes based on 2-chloro-5-X-pyridine and 2-bromo-5-X-pyridine (X = F, Cl, Br and I) were prepared to analyze the C–X2/X5⋯Cl–Cu halogen bonds (XB). The influence of X2- and X5-substituents on the respective interactions was examined by comparing them to the X2/X3⋯Cl–Cu XBs found in mono-substituted halopyridine complexes, (n-X-pyridine)2·CuCl2 (n = 2, 3 and X = Cl, Br and I). Varying the X5-halogens in (2,5-dihalopyridine)2·CuCl2, the C5–X5⋯Cl–Cu XBs follow the order F5 1 and they c…
The C–I···–O–N+ Halogen Bonds with Tetraiodoethylene and Aromatic N-Oxides
2020
The nature of C–I⋯⁻O–N⁺ interactions, first of its kind, between non-fluorinated tetraiodoethylene XB-donor and pyridine N-oxides (PyNO) are studied by single-crystal X-ray diffraction (SCXRD) and ...
Two-Photon Absorption Properties and Structures of BODIPY and Its Dyad, Triad and Tetrad.
2018
A series consisting of a dyad, a triad and a tetrad containing either two, three and four BODIPY units, respectively, has been synthesized and fully characterized and compared to two mono-BODIPY analogs (used as references). The one- and two-photon photophysical properties have been measured and the X-ray structures of four of the BODIPY derivatives have been determined. In the 700-900 nm range, the two-photon absorption (TPA) cross sections range from 30 GM to 160 GM for these compounds.
Switching of Slow Magnetic Relaxation Dynamics in Mononuclear Dysprosium(III) Compounds with Charge Density
2016
The symmetry around a Dy ion is recognized to be a crucial parameter dictating magnetization relaxation dynamics. We prepared two similar square-antiprismatic complexes, [Dy(LOMe)2(H2O)2](PF6) (1) and Dy(LOMe)2(NO3) (2), where LOMe = [CpCo{P(O)(O(CH3))2}3], including either two neutral water molecules (1) or an anionic nitrate ligand (2). We demonstrated that in this case relaxation dynamics is dramatically affected by the introduction of a charged ligand, stabilizing the easy axis of magnetization along the nitrate direction. We also showed that the application of either a direct-current field or chemical dilution effectively stops quantum tunneling in the ground state of 2, thereby increa…
Oxotris(oxalate)niobate(V): An oxalate delivery agent in the design of building blocks
2018
This work concerns the oxalate delivery process that occurs when using (NH4)3[NbO(C2O4)3]·6H2O as a suitable oxalate source in the synthesis of two compounds, [Cu(dmphen)(C2O4)(H2O)] (1) and [{Cu(dmphen)(CH3OH)}2(μ-C2O4)](ClO4)2 (2) (dmphen = 2,9-dimethyl-1,10-phenanthroline). {[Fe{HB(pz)3}(CN)2(μ-CN)]2[{Cu(dmphen)}2(μ-C2O4)]}∙xCH3OH (3) (2.0 ≤ x ≤ 2.4) was obtained by reacting 2 and PPh4[Fe{HB(pz)3}(CN)3]∙H2O [ = tetraphenylphosphonium and = tris(pyrazolyl)borate]. Crystal structures of 1–3 have been determined by single-crystal X-ray diffraction experiments: 1 is a mononuclear trigonal bipyramidal copper(II) species, 2 is a centrosymmetric oxalato-bridged dicopper(II) complex, and 3 consi…
Mixed phenoxo and azido bridged dinuclear nickel(II) and copper(II) compounds with N,N,O-donor schiff bases: Synthesis, structure, DNA binding, DFT a…
2019
Abstract Two dinuclear complexes, µ-phenoxo, µ1,1-azido bridged [Ni2(L)2(µ1,1-N3)(N3)(CH3OH)] (1) and µ-phenoxo, µ1,1-azido bridged [Cu2(L)2(µ1,1-N3)(N3)] (2) bearing HL as a blocking co-ligand produced by the 1:1 condensation of N-methyl 1,3 propanediamine with o-vanillin have been synthesized and successfully characterized by elemental analyses, IR and electronic spectroscopy, single-crystal X-ray diffraction for 1 and DFT optimization for 2. X-ray crystal structure discloses that the asymmetric unit of 1 consists of two nickel(II) ions exhibiting a six-coordinate octahedral coordination with µ-phenoxo, µ1,1-azido bridging dimeric structure. The DFT optimization of 2 reveals the five-coor…
Synthesis, molecular structures and EPR spectra of the paramagnetic cuboidal clusters with Mo3S4Ga cores
2017
Electron precise [Mo3(l3-S)(l-S)3(diphos)3Br3]Br (diphos = dppe, dmpe) incomplete cuboidal clusters with six cluster skeletal electrons (CSE) were converted into paramagnetic cuboidal [Mo3(GaBr)(l3-S)4- (diphos)3Br3] clusters by treatment with elemental Ga. The new heterobimetallic complexes with nine CSE possess a doublet ground state with the unpaired electron density delocalized over the three molybdenum atoms.
Electron Accumulative Molecules.
2018
With the goal to produce molecules with high electron accepting capacity and low reorganization energy upon gaining one or more electrons, a synthesis procedure leading to the formation of a B–N(aromatic) bond in a cluster has been developed. The research was focused on the development of a molecular structure able to accept and release a specific number of electrons without decomposing or change in its structural arrangement. The synthetic procedure consists of a parallel decomposition reaction to generate a reactive electrophile and a synthesis reaction to generate the B–N(aromatic) bond. This procedure has paved the way to produce the metallacarboranylviologen [M(C2B9H11)(C2B9H10)-NC5H4-…