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Ligand Containing (ligand + containing)
Selected AbstractsCobalt(III) Complexes of a Tripodal Ligand Containing Three Imidazole Groups: Properties and Structures of Racemic and Optically Active SpeciesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 8 2008Hirofumi Nakamura Abstract The complex [Co(H3L)](ClO4)3·H2O (1), where H3L {tris[2-(4-imidazoylmethylideneamino)ethyl]amine} is a tripodal ligand obtained by condensation of tris(2-aminoethyl)amine and 4-formylimidazole in a 1:3 molar ratio, was synthesized and optically resolved by fractional crystallization of the diastereomeric salt with [Sb2{(R,R)-tart}2]2, [(R,R)-tart = (2R,3R)-tartrate(4,) ion]. From the less soluble part, ,-[Co(H2L)][Sb2{(R,R)-tart}2]·4H2O (2) was isolated. Starting from 2, two optically active complexes, ,-[Co(H3L)](ClO4)3·1.5H2O (,- 1) and ,-[Co(L)] (,- 3), were obtained. The crystal structures of these complexes are compared with those of the racemic structures. ,- 1 shows an unusually strong circular dichroism (, = 488 nm, ,, = ,7.74 M,1,cm,1) in the first d,d absorption band region. The effects of deprotonation,reprotonation of the uncoordinated imidazole NH groups of ,-[Co(H3L)]3+ on the UV/Vis and CD spectra and on the cyclic voltammograms were studied in methanol. Although the deprotonation,reprotonation reactions are reversible, the redox couple for the completely deprotonated species [CoIII/II(L)]0/, is not observed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] A Novel Tripodal Ligand Containing Three Different N -Heterocyclic Donor Functions and Its Application in Catechol Dioxygenase MimickingCHEMISTRY - A EUROPEAN JOURNAL, Issue 22 2009Marit Wagner Dipl.-Chem. Abstract Prominent donors: A pyridyl, an imidazolyl, and a pyrazolyl donor function are part of the novel tripodal ligand depicted, which thus combines three of the most prominent donors applied in ligands for bioinorganic chemistry within one coordination unit. To exploit its behaviour and potential, first investigations have been carried out in relation to catechol dioxygenase mimicry. We describe a novel chiral ligand, L, in which three different N -donor functions are linked to a methoxymethine unit: a methylpyrazole derivative, a methylimidazole unit, and a pyridyl residue. Complexes with FeCl2, FeBr2, and FeCl3 have been synthesized and fully characterized, including with respect to their molecular structures. While in combination with FeCl3L coordinates in a tripodal fashion, with FeX2 (X=Cl, Br) it binds only through two functions and the pyridyl unit remains dangling. For potential modelling of intradiol and extradiol catechol dioxygenase reactivity, the complexes [LFeCl2], 1, and [LFeCl3], 3, have been treated with 3,5-di- tert -butylcatechol, triethylamine, and O2. Both complexes yielded similar results in such investigations, since the LFeII,catecholate complex reacts with O2 through one-electron oxidation in the first step. Employing 3 in acetonitrile solution, intradiol cleavage occurred, although the undesired quinone was formed as the main product. If reagents were added (NaBPh4, H+) or reaction conditions were chosen (CH2Cl2 instead of CH3CN as the solvent) that made the coordination sphere at the iron centre more accessible for a third substrate donor function, an alternative reaction route, presumably involving O2 binding at the metal, became more important, which led to extradiol cleavage. In the extreme case (CH2Cl2 as the solvent and with the addition of NaBPh4), mainly the extradiol cleavage products were formed; the intradiol products were only observed as side products then and quinone formation became negligible. Protonated base functions in the second coordination sphere increased the efficiency of extradiol cleavage only slightly. The obtained results are in line with current understanding of the function of intradiol/extradiol dioxygenases. [source] Modular Routes Towards New N,O-Bidentate Ligands Containing an Electronically Delocalised ,-Enaminone Chelating BackboneEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2008Udo Beckmann Abstract Polyketones are synthesised by a transition-metal-catalysed copolymerisation of olefins and carbon monoxide. Nickel complexes with N,O-chelating ligands turned out to be promising catalysts in that field. In this work a series of new N,O ligands with an electronically delocalised ,-enaminone backbone were synthesised and fully characterised. The ligand design was inspired by the ligand found in the most efficient nickel catalyst for polyketone synthesis and developed to a highly modular LEGO® -like arsenal of reactions to versatile substituted ,-enaminone ligands. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Preparation of New Ferrocenylmonophosphine Ligands Containing Two Planar Chiral Ferrocenyl Moieties and Their Use for Palladium-Catalyzed Asymmetric Hydrosilylation of 1,3-Dienes.CHEMINFORM, Issue 15 2003Jin Wook Han Abstract For Abstract see ChemInform Abstract in Full Text. [source] | ||||||||||