Search results for "Ordination"
showing 10 items of 1367 documents
Syntheses, crystal structures and magnetic properties of one- and two-dimensional pap-containing copper(II) complexes (pap = pyrazino[2,3- f ][4,7]…
2001
Three polynuclear complexes containing copper(II) and pyrazino[2,3-f][4,7]phenanthroline (pap) as the basic building blocks have been prepared [Cu2(pap)(H2O)2(NO3)3]n[NO3]n1, [Cu4(pap)4Cl7]nCln·15nH2O 2, and [Cu4(pap)4(H2O)4(C4O4)2]n[C4O4]n[NO3]2n·12nH2O 3, and their crystal structures and variable-temperature magnetic susceptibilities determined. Compound 1 is a single stranded zigzag chain where pap and nitrate alternate as bridges between the copper atoms. The copper coordination geometry is to a first approximation distorted square pyramidal, but with an additional semi-coordinated oxygen from non-bridging nitrate groups. The bridging nitrate coordinates in the apical position to both c…
White Phosphorus Is Air-Stable Within a Self-Assembled Tetrahedral Capsule
2009
Molecular Fire Quencher Cage-shaped molecular assemblies can regulate the reactivity of smaller molecules trapped within them. Mal et al. (p. 1697 ) extend this approach to enable the protection of elemental white phosphorus (P 4 ), a substance that rapidly ignites on contact with oxygen. The tetrahedral cages self-assemble in aqueous solution through coordination of six ligands to four iron ions, and efficiently capture phosphorus from a suspension. The water-soluble host-guest constructs were stable in air for at least 4 months, but released intact P 4 rapidly on displacement by added benzene.
Synthesis, crystallographic and electrochemical study of ethynyl[2.2]paracyclophane derived cobalt metallatetrahedranes
2012
Abstract A series of alkynyl cobalt complexes [Co2(μ-η2-HCC–PCP)(CO)6−nLn] [n = 0 (2); n = 2, L2 = dppa (3), dppm (4), dcpm (6), 2 P(OPh)3 (7)] and [Co2(CO)4L2]2(μ-η2:μ-η2-HCC–PCP–CCH)] (L2 = dppm (8), dcpm (9); (PCP = [2.2]paracyclophane) has been prepared and characterized. The molecular structures of 3 and 4, as well as that of [Co2(CO)4(μ-CO)2(μ2-dcpm)] (5), have been determined by X-ray diffraction. Electrochemical studies (Cyclic Voltammetry, Rotating Disk Electrode) and luminescence spectroscopy have been used to evaluate the extent of the electronic communication through the PCP motif using the “Co2C2” centres as a probe. No electronic coupling between the Co2(CO)n centres via the b…
Phospholylmethano P-chirogenic-phosphine-borane as P-(η2-BH3)-chelating ligands of rhodium (I): Synthesis, characterization and asymmetric hydrogenat…
2021
International audience; The stereoselective synthesis of new phospholylmethano P-chirogenic-phosphine-borane was achieved by P-C bond formation of the bridge, using electrophilic or nucleophilic P*-building blocks. These P1CH2P2*.BH3 ligands behaved as chelating (κ1-P1)-(η2-BH3) entities towards the cationic rhodium(I) centre. The resulting chiral rhodium complexes were tested in asymmetric rhodium catalyzed hydrogenation of methyl 2-(acetamido)acrylate.
Oxalate, squarate and croconate complexes with bis(2-pyrimidylcarbonyl)amidatecopper(II): synthesis, crystal structures and magnetic properties
2005
Abstract The preparation and magnetic properties of three copper(II) compounds of formulae [Cu2(bpcam)2(H2O)2(C2O4)] (1), [Cu2(bpcam)2(H2O)4(C4O4)] · 10 H2O (2) and Cu2(bpcam)2(C5O5)(H2O)3 (3) [bpcam = bis(2-pyrimidyl)amidate, C 2 O 4 2 - = dianion of oxalic acid , C 4 O 4 2 - = dianion of 3 , 4 - dihydroxycyclobut - 3 - ene - 1 , 2 - dione and C 5 O 5 2 - = dianion of 4 , 5 - dihydroxycyclopent - 4 - ene - 1 , 2 , 3 - trione ] are reported. The structures of two of them (1 and 2) have been solved by single crystal X-ray diffraction and consists of centrosymmetric discrete copper(II) dinuclear units bridged by bis-bidentate oxalate (1) and bis-monodentate squarate (2), with the bpcam group …
Structure and magnetic properties of a linear oximato-bridged tetranuclear copper(II) complex
1998
Abstract The tetranuclear copper(II) complex of formula [Cu2(dmg)(Hdmg)(terpy)]2(ClO4)2 (1) (H2dmg = dimethylglyoxime and terpy = 2,2′:6′,2″-terpyridine) has been synthesized and its crystal structure determined by X-ray diffraction methods. It crystallizes in the triclinic system, space group P(−1), with a = 14.382(3), b = 13.728(3), c = 8.979(2) A, α = 96.99(2), β = 111.85(2), γ = 111.22(3)°, V = 1465.0(9) A3, Z = 1, Dc = 1.607 g cm−3, Mr = 1418.0, F(000) = 719, λ(Mo Kα) = 0.71073 A, μ(Mo Kα) = 16.61 cm−1 and T = 298 K. A total of 4891 reflections were measured over the range 2 ≤ θ ≤ 25° and 4393 of them were unique (I > 2.5σ(I) and used in the structural analysis. The structure of 1 may …
Applications and stereoselective syntheses of P-chirogenic phosphorus compounds.
2016
International audience; Phosphorus compounds bearing chirality on the P-center are usually qualified as P-chirogenic or P-stereogenic. This chemical class concerns natural products, agrochemistry, molecular materials, biology and pharmacy, although it is certainly in coordination chemistry and in asymmetric catalysis using chiral transition metal complexes that P-chirogenic phosphorus compounds are the most used. The chiral phosphine ligands and their uses in asymmetric metal-catalyzed reactions have been widely reviewed in literature. However, an overview covering the applications as well as the stereoselective syntheses of all classes of phosphorus compounds has not yet been provided. Thi…
Bidirectional Chemo-Switching of Spin State in a Microporous Framework
2009
The ins and outs of spin: Using the microporous coordination polymer {Fe(pz)[Pt(CN)(4)]} (1, pz=pyrazine), incorporating spin-crossover subunits, two-directional magnetic chemo-switching is achieved at room temperature. In situ magnetic measurements following guest vapor injection show that most guest molecules transform 1 from the low-spin (LS) state to the high-spin (HS) state, whereas CS(2) uniquely causes the reverse HS-to-LS transition.
Polyamines : études et applications
2008
International audience
Synthèse et étude physico-chimique de ligands macrocycliques, macrobicycliques et macrotricycliques dérivés du 5,12-dioxocyclame
2002
The synthesis and the physico-chemical studies of macropolycyclic ligands based on 5,12-dioxocyclam L1 are presented. The first part of this dissertation presents the structural and physico-chemical properties of L1 and its N-substituted derivatives L2 and L3. A potentiometric study reveald a cooperative protonation of the two macrocyclic ligands L1 and L2 whereas the study of the macrotricycle L3 in a methanol-water mixture revealed a sequential cooperative diprotonation of the four tertiary amines. The square planar nickel and copper complexes were synthesized and characterized using infrared, UV-vis and ESR spectgroscopy. The spectroscopic studies showed the presence of intermolecular hy…