Search results for "Crystal"
showing 10 items of 22886 documents
Diferratricarbaboranes of thesubcloso-[(η5-C5H5)2Fe2C3B8H11] Type, the First Representatives of the 13-Vertex Dimetallatricarbaborane Series
2003
Treatment of the [2-Cp-9-tBuNH-closo-2,1,7,9-FeC 3 B 8 H 1 0 ] (1) ferratricarbollide (Cp = η 5 -C 5 H 5 -) with Na + C 1 0 H 8 - in 1,2-dimethoxyethane (DME) at room temperature produced an air-sensitive transient anion with a tentatively identified nido-[tBUNH-CpFeC 3 B 8 H 1 0 ] 2 - constitution. In-situ reaction of this low-stability ion with [CpFe(CO) 2 I] or [CpFe(CO) 2 ] 2 generated three violet diferratricarbaboranes identified as paramagnetic subcloso complexes [4,5-Cp 2 - -4,5,1,6,7-Fe 2 C 3 B 8 H 1 1 ] (2; yield 2%), [4,5-Cp 2 - -4,5,1,7,12-Fe 2 C 3 B 8 H 1 1 ] (3; yield 2%), and [7-tBuNH-4,5-Cp 2 - -4,5,1,7,12-Fe 2 C 3 B 8 H 1 0 ] (4; yield 14%). These first representatives of t…
Chiral and Racemic Spin Crossover Polymorphs in a Family of Mononuclear Iron(II) Compounds
2017
[EN] Understanding the origin of cooperativity and the equilibrium temperature of transition (T1/2) displayed by the spin-crossover (SCO) compounds as well as controlling these parameters are of paramount importance for future applications. For this task, the occurrence of polymorphism, presented by a number of SCO complexes, may provide deep insight into the influence of the supramolecular organization on the SCO behavior. In this context, herein we present a novel family of mononuclear octahedral FeII complexes with formula cis- [Fe(bqen)(NCX)2], where bqen is the chelating tetradentate ligand N,N¿-bis(8-quinolyl)ethane-1,2-diamine and X = S, Se. Depending on the preparation method, these…
Electron-Sponge Behavior, Reactivity and Electronic Structures of Cobalt-Centered Cubic Co9Te6(CO)8 Clusters
2008
Extended investigations of the reaction sequence [Cp′2Nb(Te2)H]/CH3Li/[Co2(CO)8] (Cp′ = tBuC5H4) led to the identification of Lin[3] {3 = [Co9Te6(CO)8]; n = 1, 2} salts through their transformation with [PPN]Cl into [PPN]n[3] (PPN = Ph3PNPPh3). These compounds form in the solid state columnar ([PPN][3]) or undulated 2D ([PPN]2[3]) supramolecular networks. Electrochemical studies of [Cp*2Nb(CO)2][3] (Cp* = C5Me5) or [Na(THF)6][3] revealed the presence of the redox couples [3]–/[3]2–/[3]3–/[3]4–/[3]5– regardless of the nature of the cation, whereas in the anodic part oxidative degradation of the cluster takes place. This behavior is in agreement with the observation that [3]– containing salts…
A hybrid magnet with coexistence of ferromagnetism and photoinduced Fe(iii) spin-crossover
2011
International audience; The insertion of a [Fe(sal2-trien)]+ complex cation into a 2D oxalate network results in a hybrid magnet with coexistence of magnetic ordering and photoinduced spin-crossover (LIESST effect) in compound [FeIII(sal2-trien)][MnIICrIII(ox)3]*(CH2Cl2) (1). A complete photomagnetic characterization together with a detailed structural analysis of the low-spin (LS) and high-spin (HS) structures of 1 is presented in order to understand such unusual behavior. This very rare and unexpected property in a FeIII spin-crossover complex, has been attributed to the strong distortion exhibited by the metastable HS state. Furthermore, 1 has shown that, in contrast to what has been pre…
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…
Combining Cyanometalates and Coordination Clusters: An Alternative Synthetic Route toward Original Molecular Materials
2013
International audience; With the discovery of molecules or molecule-based compounds that can display blocked magnetization, magnetic ordering or switchable magnetic bistability, the research efforts devoted to molecular magnetic materials have considerably increased over the past two decades, fully exploiting the advantages of the bottom-up approach. 1-4 This research field focuses on promising properties for potential technological applications such as information storage, quantum computing and spintronics at the molecular scale, but it also provides fundamental insights into original quantum phenomena. 5,6 Coordination chemists have developed efficient synthetic tools for the preparation …
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…
Systematic Investigation of Resorcin[4]arene-Based Cavitands as Affinity Materials on Quartz Crystal Microbalances.
2017
Resorcin[4]arene cavitands are well-known supramolecular hosts, and their outstanding guest-binding abilities in solution have been studied in detail in recent decades. In a systematic approach, different resorcin[4]arene cavitands and container molecules are characterized as affinity materials for gravimetric sensing using high-fundamental-frequency quartz crystal microbalances. Analysis of their affinity toward a series of various analytes reveals a remarkable dependence of both selectivity and sensitivity on the shape, accessibility, and size of the cavity, along with their supramolecular interactions with the host molecules.
Supramolecular chemistry of metalloporphyrins
2009
International audience