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Malonate Anion (malonate + anion)
Selected AbstractsRing Closure of Alkoxycarbonyl(tetracarbonyl)pyruvoyliron Complexes into Metallalactones Induced by Nucleophilic Attack of CarbanionsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 7 2006Patrice Cabon Abstract The reaction of carbanions with the pyruvoyl-substituted iron complex [(CO)4Fe(CO2CH3){C(O)C(O)CH3}] (1) affords the anionic trifunctionalized metallalactones [(CO)3Fe{C(O)C(CH3)(CRR,R,)OC4(O)(Fe,C4)}(CO2CH3)], (3), whose formation results from the addition of the nucleophile to the , carbonyl of the pyruvoyl moiety, followed by attack of the oxygen of this , carbonyl on a terminal carbonyl ligand. These anionic lactones react, at low temperature, with HCl to give rise to the neutral lactones [(CO)4Fe{C(O)C(CH3)(CRR,R,)OC4(O)(Fe,C4)}] (2), which were previously obtained by addition of NuH nucleophiles to 1. Complex 3(3), whose lactonic ring formation has been performed using the diethyl malonate anion (R = R, = CO2C2H5; R, = H), and the dimethyl-substituted neutral lactone 2(1) (R = R, = R, = H) have been characterized by X-ray diffraction studies. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Hexaazamacrocycle Containing Pyridine and Its Dicopper Complex as Receptors for Dicarboxylate AnionsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 22 2005Feng Li Abstract The host,guest binding interactions of the hexaazamacrocycle [26]py2N4, in its tetraprotonated form H4[26]py2N44+ as well as in its dicopper(II) complex [Cu2([26]py2N4)(H2O)4]4+, with dicarboxylate anions of different stereoelectronicrequirements, such as oxalate (ox2,), malonate (mal2,), succinate (suc2,), fumarate (fu2,) and maleate (ma2,), were evaluated. The association constants were determined using potentiometric methods in aqueous solution, at 298.0 K and 0.10 mol·dm,3 KCl. These values for the tetraprotonated ditopic receptor with the dicarboxylate anions revealed that the main species in solution corresponds to the formation of {H4[26]py2N4(A)}2+ (pH , 4,9), A being the substrate anion. The values determined are not especially high, but the receptor exhibits selectivity for the malonate anion. The study of the cascade complexes revealed several species in solution, involving mononuclear and dinuclear complexes, mainly protonated and hydrolysed species, as well as the expected complexes [Cu2([26]py2N4)(A)(H2O)x]2+ or [Cu2([26]py2N4)(A)2(H2O)y]. Ox2, and mal2, form cascade complexes with only one anion, which will necessarily bridge the two copper atoms because of the symmetrical arrangement of the dinuclear complex. The two other studied anions, suc2, and ma2,, form species involving two substrate anions, although species with only one suc2, anion were also found. UV/Vis and EPR spectroscopy have shown that the dicopper complex can operate as a sensor to detect and quantitatively determine oxalate spectrophotometrically because of the red shift of the maximum of the visible band observed by addition of ox2, to an aqueous solution of the dinuclear copper complex. However the selectivity of [Cu2([26]py2N4)(H2O)4]4+ as a receptor for ox2, in the studied series is not sufficiently high to detect ox2, spectrophotometrically in the presence of the other anions. Molecular dynamics simulations indicated that the H4[26]py2N44+ receptor provides a large and flexible cavity to accommodate the studied anions. Molecular recognition is based in electrostatic interactions rather than in multiple hydrogen-bonding interactions acting cooperatively. By contrast, the [Cu2([26]py2N4)]4+ receptor has a well-shaped cavity with adequate size to uptake these anions as bridging ligands with formation of four Cu,O bonds. The ox2, anion is encapsulated within the cascade complex while the remaining anions are located above the N6 macrocyclic plane, suggesting a selective coordination behaviour of this receptor. In spite of our molecular simulation being carried out in gas phase, the modelling results are consistent with the solution studies. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Preparation of planar-chiral multidonor phosphanylferrocene carboxamides and their application as ligands for palladium-catalysed asymmetric allylic alkylationAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 4 2010Martin Lama Abstract Amide coupling of (Sp)-2-(diphenylphosphanyl)ferrocene-1-carboxylic acid with appropriate terminal amines mediated by 1-hydroxybenzotriazole and a carbodiimide affords multi-donor amides terminally functionalized with planar-chiral (Sp)-2-(diphenylphosphanyl)ferrocen-1-yl moieties in good to excellent yields. Palladium catalysts based on these ligands efficiently promote asymmetric allylic alkylation of 1,3-diphenylallyl acetate with in situ generated dimethyl malonate anion to give the C-alkylated product with ees up to 93% at room temperature. Copyright © 2010 John Wiley & Sons, Ltd. [source] New Dihydroxy Bis(Oxazoline) Ligands for the Palladium-Catalyzed Asymmetric Allylic Alkylation: Experimental Investigations of the Origin of the Reversal of the EnantioselectivityCHEMISTRY - A EUROPEAN JOURNAL, Issue 3 2004Hassan Aït-Haddou Dr. Abstract The origin of the reversal of the enantioselectivity in the palladium-catalyzed allylic alkylation of rac -1,3-diphenyl-2-propenyl acetate with dimethyl malonate anion using chiral dihydroxy bis(oxazoline) "BO" ligands derived from (1S,2S)-(+)-2-amino-1-phenyl-1,3-propanediol was investigated. To determine the structural effects of the dihydroxy BO ligand on this unique phenomenon, new homochiral dihydroxy BO ligands were prepared from L -threonine and L -serine and were assessed in the transformation. The results obtained with these novel BO ligands, compared with the one obtained by using the dihydroxy BO ligands derived from (1S,2S)-(+)-2-amino-1-phenyl-1,3-propanediol, reveal that the reversal in the enantioselectivity observed with the dihydroxy BO ligand depends on the structure of the ligand. The effect of different bases used to generate the dimethyl malonate anion was also examined. The results are discussed in terms of the interaction of one hydroxy group in the intermediate ,-allyl palladium complex with the dimethyl malonate anion. [source] Two Multi-armed Neutral Receptors for ,,, -Dicarboxylate AnionsCHINESE JOURNAL OF CHEMISTRY, Issue 4 2006Jin-Long Wu Abstract Two new multi-armed neutral receptors 1 and 2 containing thiourea and amide groups were synthesized by simple steps in good yields. Receptors 1 and 2 have a better selectivity and higher association constants for malonate anion than other anions examined by the present work. In particular, distinct color changes were observed upon addition of dicarboxylate anions to the solution of 1 in DMSO. The UV-Vis and fluorescence spectra data indicate that a 1:2 stoichiometry complex was formed between compound 1 or 2 and dicarboxylate anions of shorter carbon chain, and a 1:1 stoichiometry complex was formed between compound 1 or 2 and dicarboxylate anions of longer carbon chain through hydrogen bonding interactions. [source] The crucial role of C,H...O and C=O..., interactions in the building of three-dimensional structures of dicarboxylic acid,biimidazole compoundsACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2009Xiao-Li Gao The supramolecular architectures of three dicarboxylic acid,biimidazole compounds, namely, 2,2,-biimidazolium malonate, C6H8N42+·C3H2O42,, (I), 2,2,-bi(1H -imidazole) succinic acid, C6H6N4·C4H6O4, (II), and 2,2,-biimidazolium 2,2,-iminiodiacetate chloride, C6H8N42+·C4H6NO4,·Cl,, (III), are reported. The crystal structures are assembled by the same process, namely double conventional N,H...O or O,H...N hydrogen bonds link the dicarboxylates and biimidazoles to form tapes, which are stacked in parallel through lone-pair,aromatic interactions between carbonyl O atoms and biimidazole groups and are further linked via weak C,H...O interactions. The C=O..., interactions involved in stacking the tapes in (II) and the C,H...O interactions involved in linking the tapes in (II) and (III) demonstrate the crucial role of these interactions in the crystal packing. There is crystallographically imposed symmetry in all three structures. In (I), two independent malonate anions have their central C atoms on twofold axes and two biimidazolium dications each lie about independent inversion centres; in (II), the components lie about inversion centres, while in (III), the unique cation lies about an inversion centre and the iminiodiacetate and chloride anions lie across and on a mirror plane, respectively. [source] | ||||||||||