Search results for "cobalt."
showing 10 items of 969 documents
Trans-dicyanobis(acetylacetonato)ruthenate(III) as a precursor to build novel cyanide-bridged RuIII–MII bimetallic compounds [M=Co and Ni]
2006
Abstract The use of the mononuclear complex trans-[Ru(acac)2(CN)2]− as a ligand towards the preformed species [Ni2L(H2O)2Cl2], [Co(dmphen)](NO3)2, [Ni(dmphen)](NO3)2 and [Co(H2O)6](NO3)2 afforded the novel cyanide-bridged bimetallic compounds of formula [{Ru(acac)2(CN)2}{Ni2(L)(H2O)2}]{Ru(acac)2(CN)2}·2H2O (1), [{Ru(acac)2(CN)2}{Co(dmphen)(NO3)}]·H2O (2) and [{Ru(acac)2(CN)2}{Ni(dmphen)(NO3)}]·H2O (3) and [{Ru(acac)2(CN)2}2Co] (4) [Hacac = acetylacetone, dmphen = 2,9-dimethylphenanthroline and H2L = 11,23-dimethyl-3,7,15,19-tetrazatricyclo[19.3.1.19,13]hexacosa-2,7,9,11,13(26),14,19,21(25),22,24-decaene-25,26-diol]. Their syntheses, X-ray crystal structures and magnetic properties are repor…
C–S bond cleavage by cobalt: synthesis, characterization and crystal structure determination of 1,2-di-(o-salicylaldiminophenylthio)ethane and its Co…
2002
1,2-Di-(o-salicylaldiminophenylthio)ethane reacts with Co(II) salts to form a complex with oxidative cleavage of the C–S bond, to result in the formation of a Co(III) complex of the cleaved ligands.
Supramolecular 2D/3D isomerism in a compound containing heterometallic Cu(II)2Co(II) nodes and dicyanamide bridges.
2014
Three new heterometallic copper(II)-cobalt(II) complexes [(CuL(2))2Co{dca}2]·H2O(1), [(CuL(1))2Co{dca}2]n (2a), and [(CuL(1))2Co{dca}2]n (2b) [dca(-) = dicyanamide = N(CN)2(-)] have been synthesized by reacting the "metallo-ligand" [CuL(1)] or [CuL(2)] with cobalt(II) perchlorate and sodium dicyanamide in methanol-water medium (where H2L(1) = N,N'-bis(salicylidene)-1,3-propanediamine and H2L(2) = N,N'-bis(α-methylsalicylidene)-1,3-propanediamine). The three complexes have been structurally and magnetically characterized. Complex 1 is a discrete trinuclear species in which two metallo-ligands coordinate to a cobalt(II) ion through the phenoxido oxygen atoms along with two terminally coordina…
Synthesis of μ-C2S44− Cobalt Complexes by Activation of the 1,3,4,6-tetrathiapentalene-2,5-dione, and Electrochemical Study of [(Cp*Co)2(μ-C2S4)]
2002
The bimetallic complex [Cp(*)Co)2(μ-C2S4)] in which the two metal centres are linked by an ethylenetetrathiolate C2S44− unit, was synthesized in high yield by oxidative addition of 1,3,4,6 tetrathiapentalene-2,5-dione to [Cp(*)Co(CO)2]. The X-ray crystal structure of the intermediate product Cp*Co(dmid) (dmid2− = 4,5-disulfanyl-1,3-dithiol-2-onate) is presented. The electrochemical behaviour of the [(Cp*Co)2(μ-C2S4)] complex was studied in detail in the oxidative range. This study has shown that the nature of the product obtained after oxidation depends on the presence of complexing agent in the solution. The mechanism has been elucidated in a CH2Cl2 solution in the presence of P(OMe)3. In …
Magnetic Properties of End-to-End Azide-Bridged Tetranuclear Mixed-Valence Cobalt(III)/Cobalt(II) Complexes with Reduced Schiff Base Blocking Ligands…
2019
Two tetranuclear mixed-valence cobalt(III/II) complexes having the general formula [(μ1,3-N3){CoII(Ln)(μ-O2CC6H4NO2)CoIII(N3)}2]PF6 (where H2L1 and H2L2 are two reduced Schiff base ligands) have been synthesized and characterized. The structures of both complexes show cobalt(II) and cobalt(III) centers with a distorted octahedral geometry with cobalt(III) and cobalt(II) centers located at the inner N2O2 and outer O4 cavities of the reduced Schiff base ligands, respectively. The oxidation states of both cobalt centers have been confirmed by bond valence sum (BVS) calculations. The magnetic properties show that both compounds behave as cobalt(II) dimers connected through an end-to-end azido b…
Theoretical Insights into the Ferromagnetic Coupling in Oxalato-Bridged Chromium(III)-Cobalt(II) and Chromium(III)-Manganese(II) Dinuclear Complexes …
2012
Two novel heterobimetallic complexes of formula [Cr(bpy)(ox)(2)Co(Me(2)phen)(H(2)O)(2)][Cr(bpy)(ox)(2)]·4H(2)O (1) and [Cr(phen)(ox)(2)Mn(phen)(H(2)O)(2)][Cr(phen)(ox)(2)]·H(2)O (2) (bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline, and Me(2)phen = 2,9-dimethyl-1,10-phenanthroline) have been obtained through the "complex-as-ligand/complex-as-metal" strategy by using Ph(4)P[CrL(ox)(2)]·H(2)O (L = bpy and phen) and [ML'(H(2)O)(4)](NO(3))(2) (M = Co and Mn; L' = phen and Me(2)phen) as precursors. The X-ray crystal structures of 1 and 2 consist of bis(oxalato)chromate(III) mononuclear anions, [Cr(III)L(ox)(2)](-), and oxalato-bridged chromium(III)-cobalt(II) and chromium(III)-manganese(II) din…
Identification of lipid binders in paintings by gas chromatography
2001
Abstract The influence of the presence and the type of pigments in the lipid binding media of paintings were studied by gas chromatography with flame ionization detector. The drying oils were linseed stand oil, poppy oil and sunflower oil, and the pigments studied were cadmium red, cobalt blue, tin white, lead white, chalk and plaster of Paris, commonly used in paintings. The results indicate that the stearic/palmitic ratio and the presence of pigments are quite stable during ageing. However, some differences in the oleic acid/palmitic acid ratio were found, depending on the type of pigment present in the lipid binding media. These variations are related to the drying effect of the pigments…
A new selective fluorogenic probe for trivalent cations.
2012
[EN] A new selective chromo-fluorogenic probe for Fe 3+, Cr 3+ and Al 3+ is reported. Detection limits are in the ¿M range and the fluorogenic sensing ability could be observed by the naked eye when illuminated with UV-light. No response is observed with divalent cations. © 2012 The Royal Society of Chemistry.
Ferromagnetic coupling and magnetic anisotropy in oxalato-bridged trinuclear chromium(iii)-cobalt(ii) complexes with aromatic diimine ligands
2010
Two novel heterotrinuclear chromium(III)-cobalt(II) complexes of formula {[Cr(III)(bpy)(ox)(2)](2)Co(II)(Me(2)bpy)}.2H(2)O (1) and {[Cr(III)(phen)(ox)(2)](2)Co(II)(Me(2)bpy)}.1.5H(2)O (2) [ox = oxalato, bpy = 2,2'-bipyridine, Me(2)bpy = 6,6'-dimethyl-2,2'-bipyridine, and phen = 1,10-phenanthroline] have been synthesized using the "complex-as-ligand/complex-as-metal" strategy. The X-ray crystal structure of 2 consists of neutral oxalato-bridged Cr(III)(2)Co(II) bent entities formed by the coordination of two anionic [Cr(III)(phen)(ox)(2)](-) complexes through one of their oxalato groups toward a cationic cis-[Co(II)(Me(2)bpy)](2+) complex. The three tris(chelated), six-coordinated metal atom…
Pauson-Khand reaction of internal dissymmetric trifluoromethyl alkynes. Influence of the alkene on the regioselectivity.
2014
Abstract: The scope of the Pauson-Khand reaction (PKR) of internal trifluoromethyl alkynes, previously described with norbornadiene, is expanded to norbornene and ethylene. A thorough structural analysis of the resulting PK adducts has been carried out to unveil that α-trifluoromethylcyclopentenones are preferred in all cases, independently of the electronic properties of the alkyne. The regioselectivity observed with norbornadiene and ethylene is higher than in the case of norbornene.