Search results for "Tripodal ligand"
showing 10 items of 14 documents
Cis- and trans molybdenum oxo complexes of a prochiral tetradentate aminophenolate ligand : Synthesis, characterization and oxotransfer activity
2020
Abstract Reaction of [MoO2Cl2(dmso)2] with the tetradentate O2N2 donor ligand papy [H2papy = N-(2-hydroxybenzyl)-N-(2-picolyl)glycine] leads to formation of the dioxomolybdenum(VI) complex [MoO2(papy)] (1) as a mixture of cis and trans isomers. Recrystallization from methanol furnishes solid cis-1, whereas the use of a dichloromethane-hexane mixture allows for the isolation of the trans-1 isomer. Both isomers have been structurally characterized by X-ray crystallography and the energy difference between the isomeric pair has been investigated by electronic structure calculations. Optimization of two configurational isomers in the gas phase predicts the trans isomer to lie 2.5 kcal/mol lower…
The [Pd(bipy)]2+ “merry-go-round”: Insights into the lability of the Pd–N bond
2009
Abstract Two tripods (1 and 2) featuring pyrimidinyl pendant arms have been synthesized from 5-(1H-pyrazol-3-yl)-pyrimidine (5) and 1,3,5-tribromomethylbenzene derivatives. Reaction with three equivalents of [Pd(bipy)](NO3)2 to form a macrotricycle closed by palladium coordination unexpectedly afforded the mononuclear species [Pd(1)(bipy)]2+ and [Pd(2)(bipy)]2+. These complexes show fluxional behavior on the 1H NMR timescale, the [Pd(bipy)]2+ fragment hopping between the pyrimidinyl coordinating moieties. The ΔGc‡’s estimated by the coalescence method are temperature independent, which means that ΔSc‡ = 0. This indicates that the “merry-go-round” process of [Pd(bipy)]2+ occurs intramolecula…
Ti(iv)-amino triphenolate complexes as effective catalysts for sulfoxidation
2010
C 3 -symmetric Ti (IV) amino triphenolate complexes efficiently catalyze, without previous activation and in excellent yields, the oxidation of sulfides at room temperature, using both CHP and the more environment friendly aqueous hydrogen peroxide as terminal oxidants, with catalyst loadings down to 0.01%. The Ti(IV) catalysts and the intermediate Ti(IV)-peroxo complexes have been characterized in solution by 1H NMR and ESI-MS techniques and via density functional studies.
Stepwise formation of a pentanuclear Ni4Cu heterometallic complex exhibiting a vertex-sharing defective double-cubane core and diphenoxo- and phenoxo…
2013
Sequential reaction of a N5O3 octadentate tripodal ligand with Ni(2+) and subsequently with Cu(2+) and azide ligand afforded the first example of a heterobridged (phenoxo/μ(1,1)-azido) pentanuclear heterometallic (Ni4Cu) compound, which exhibits a centrosymmetric vertex-sharing defective double-cubane structure. The study of the magnetic properties reveals that the compound shows ferromagnetic interaction interactions, leading to an S = 9/2 spin ground state. Density functional theory calculations on the X-ray structure and model compounds predict ferromagnetic interactions through the magnetic exchange pathways involving each couple of metal ions.
Reversible coordination of dioxygen by tripodal tetraamine copper complexes incorporated in a porous silica framework.
2010
The present study reports the synthesis and rational design of porous structured materials by using a templating method. A tetraethoxysilylated tripodal tetraamine (TREN) was covalently incorporated in a silica framework with a double imprint: A surfactant template and a metal ion imprint. The presence of a cationic surfactant (CTAB) endowed the material with a high porosity, and the tripodal or square-pyramidal topology of the ligand was preserved thanks to the use of the silylated Cu(II) complex. After removal of the surfactant and de-metalation, the incorporated tetraamine was quantitatively complexed by CuCl(2) and the material has shown after thermal activation that a reversible bindin…
A New Rhodium(III) Complex with a Tripodal Bis(imidazolylidene) Ligand. Synthesis and Catalytic Properties
2003
A new bis(imidazolylidene) tripodal ligand has been obtained by a simple method. The coordination of this ligand to Rh provides the first Rh(III) complex with a bis(carbene) ligand in a tripodal coordination, and its catalytic properties toward hydrogen transfer have been examined.
Kinetic study of the oxidation of [Fe(CN)6]4− by [Co(NH3)4pzCO2]2+ and S2O82- in the presence of the tripodal ligand Tren Aminopropil
2011
Abstract Oxidations (electron transfers) of [Fe(CN)6]4− by [Co(NH3)4pzCO2]2+ and S 2 O 8 2 - have been studied in solutions containing the receptor N,N′,N″-(aminopropil)-tris (2-aminoetil) amina [Tren Aminopropil, TAL], which can incorporate [Fe(CN)6]4− and S 2 O 8 2 - but not the cobalt complex. The results can be explained using the Bronsted equation that allows to obtain the binding constant of the transition state, a parameter that the Pseudophase Model cannot provide.
The construction of open GdIII metal–organic frameworks based on methanetriacetic acid: New objects with an old ligand
2010
11 páginas, 11 figuras, 2 esquemas.-- et al.
Mononuclear and binuclear copper(II) complexes with bis(2-imidazolyl)(bis(methoxycarbonyl)methylmethane) (BIBM), a tripodal bis(imidazole) based liga…
2013
Two new Cu(II) complexes with bis(2-imidazolyl) (bis(methoxycarbonyl)methylmethane) (BIBM), a tridentate bis(imidazole) based ligand with the formula [Cu(BIBM) 2 ](ClO 4 ) 2 ( 1 ) and [{Cu(BIBM)(H 2 O)} 2 (μ 1,2,3,4 -C 2 O 4 )](C 4 O 4 )·6H 2 O ( 2 ) have been synthesized and characterized. Compound 1 shows mononuclear cationic [Cu(BIBM) 2 ] 2+ units and perchlorate ions. The coordination around the Cu(II) ion shows a tetragonally-elongated octahedral geometry. The BIBM ligand acts as a k 3 -N,N’,O tripodal ligand, through two imidazole N atoms and a weak Cu–O(carboxymethyl) axial interaction. In the crystal structure cations and anions connect through H-bonds generating linear chains. Line…
A chiral diamine bis-phenolate complex of dioxomolybdenum(VI)
2009
Abstract A new dioxomolybdenum(VI) complex with a chiral tetradentate ligand is reported. The tripodal ligand containing two nitrogen atoms and two phenolic oxygen atoms was synthesized starting from a chiral diamine precursor. Further reaction with [MoO2(acac)2] yielded a monomeric molybdenum complex as a bright yellow solid. The structures of the molybdenum complex and the free diamine bis-phenol ligand were determined by X-ray diffraction.