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Dianion

Distribution by Scientific Domains

Chemistry	96%

Distribution within Chemistry

Crystallography	38%
General & Introductory Chemistry	20%
Organic Chemistry	13%
8 Other Subdomains	29%

Selected Abstracts

Bent and Linear Forms of the (,-Oxo)bis[trichloroferrate(III)] Dianion: An Intermolecular Effect , Structural, Electronic and Magnetic Properties

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 23 2003
Agustí Lledós
Abstract We have analyzed the great diversity of Fe,O,Fe angles, 140,180°, found in the X-ray structures of the (,-oxo)bis[trichloroferrate(III)] dianion [Cl3FeOFeCl3]2, from both experimental and theoretical points of view. Theoretical calculations show that only the linear isomer is found as a minimum on the potential energy surface. Detailed analysis of the crystal packing indicates that the angular form is due to attractive intermolecular interactions. Analysis of a selected reduced set of the 45 crystal structures retrieved from the Cambridge Structural Database allowed us to classify the bending of the [Cl3FeOFeCl3]2, dianion in three categories, depending on the balance and strength of the intermolecular O···H,X contacts. A crystal diffraction study on the bis(benzyltrimethylammonium) salt has shown both bent (144.6°) and linear (180°) forms of the (,-oxo)bis[trichloroferrate(III)] dianion. The magnetic susceptibility of this compound has been fitted by assuming two equally weighted contributions (Jang and Jlin) of the two forms, considering Jang , Jlin estimated by theoretical calculations. The obtained Jang and Jlin of ,117 and ,133 cm,1 respectively, agree well with B3LYP results. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

The Bicorannulenyl Dianion: A Charged Overcrowded Ethylene,

ANGEWANDTE CHEMIE, Issue 41 2010
David Eisenberg
Bicorannulenyl, ein großes Biaryl bestehend aus zwei ,schüsselförmigen" Corannulenen, wird nach Reduktion zum Dianion in ein sterisch überfrachtetes Ethylen umgewandelt (siehe Bild). DFT-Rechnungen und NMR-spektroskopische Untersuchungen lassen den Doppelbindungscharakter der zentralen Bindung zwischen den beiden Untereinheiten erkennen. Drei stabile Diastereomere, die sich durch Inversion und Rotation um die zentrale Bindung ineinander umwandeln lassen, wurden gefunden. [source]

Synthese und Charakterisierung von Digerma- closo -dodecaborat, einem höheren Homologen des ikosaedrischen ortho -Carborans,

ANGEWANDTE CHEMIE, Issue 42 2009
Claudia Nickl
Lücke gefüllt: Aus Germanium(II)-bromid, Decaboran und Triethylamin wurde das dimere 2,2,-Bis(1,2-digerma- closo -dodecaborat) synthetisiert. Reduktive Spaltung ergab das monomere Dianion [Ge2B10H10]2,. Mit Alkylhalogeniden wurden neutrale, disubstituierte Spezies erhalten (siehe Beispiel), die NMR-spektroskopisch und röntgenographisch charakterisiert wurden. Die Lücke in der Serie der Dihetero- closo -dodecaborane der Gruppe XIV ist nun geschlossen. [source]

ChemInform Abstract: A New Entry to 1,5-Keto Esters and Their 4,4-Dideuterio Derivatives via Methylene Chloride as "Methylene Dianion" Equivalents.

CHEMINFORM, Issue 42 2008
Kuo-Wei Lin
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

ChemInform Abstract: Vibrational Spectrum and Electronic Structure of the [B11H11]2- Dianion.

CHEMINFORM, Issue 5 2008
Elena G. Kononova
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Ozonic Acid and Its Ionic Salts: Ab initio Probing of the O42- Dianion.

CHEMINFORM, Issue 37 2004
Ben M. Elliot
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

ChemInform Abstract: Infrared Spectrum of the Hyponitrite Dianion, N2O22- , Isolated and Insulated from Stabilizing Metal Cations in Solid Neon.

CHEMINFORM, Issue 10 2002
Lester Andrews
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

New Templating Strategies with Salen Scaffolds (Salen=N,N,-Bis(salicylidene)ethylenediamine Dianion)

CHEMISTRY - A EUROPEAN JOURNAL, Issue 34 2008
Arjan
Abstract Templated approaches towards selective organic synthesis is a common feature in nature in which nucleic acid templated synthesis plays a crucial role in various fundamental biological processes. The key feature that allows control over the amazing selectivity found in natural processes is evidently the effective molarity of the reaction partners that is mediated by the macromolecular templation event. An ongoing challenge within many chemical sciences is to exploit similar templating principles and make use of synthetic systems that are designed for specific chemical conversions. Here, we describe the recent developments that involve (metallo)salen scaffolds that are used for diverse templating events (salen=N,N,-bis(salicylidene)ethylenediamine dianion). [source]

Stepwise Oxidation of the Stannole Dianion

CHEMISTRY - A EUROPEAN JOURNAL, Issue 13 2008
Ryuta Haga Dr.
Abstract Tin oxidation of stannole dianion 1 with 1.3,equivalents of oxygen gave terstannole-1,3-dianion 3. The non-aromatic nature of 3 was confirmed by X-ray crystallographic analysis. Treatment of 1 with 1,2-dibromoethane (3,equiv) gave poly(1,1-stannole) 4, the formation of which was proven by reduction of 4 with lithium to revert to the starting dianion 1. Reaction of 1 with 1,2-dibromoethane (3,equiv) in the presence of phenyllithium gave phenyl-capped ter(1,1-stannole) 7. The electronic absorption spectra of newly obtained stannoles were also measured. [source]

Ytterbocenes as One- and Two-Electron Reductants in their Reactions with Diazadienes: YbIII Mixed-Ligand Bent-Sandwich Complexes Containing a Dianion of Diazabutadiene

CHEMISTRY - A EUROPEAN JOURNAL, Issue 17 2007
Alexander
Abstract Ytterbocene [Yb(C5MeH4)2(thf)2] reacts with diazabutadiene 2,6- iPr2C6H3NCHCHNC6H3iPr2 -2,6 (DAD) as a one-electron reductant to afford a bis(cyclopentadienyl) YbIII derivative containing a DAD radical anion [Yb(C5MeH4)2(dad,.)]. However, ytterbocenes [YbCp*2(thf)2] (Cp*=C5Me5, C5Me4H) coordinated by sterically demanding cyclopentadienyl ligands act as two-electron reductants in their reactions with DAD. These reactions occur by abstraction of one Cp* ring and result in the formation of novel YbIII mixed-ligand bent-sandwich complexes, [YbCp*(dad)(thf)], in which the dianion of DAD has an uncommon terminal ,4 -coordination to the ytterbium atom. The variable-temperature magnetic measurements of complex [Yb(C5Me5)(dad)(thf)] suggest the existence of redox tautomerism for this compound. [source]

Synthesis, characterization of an unusual crystalline material with tartrate

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2008
Yongbing Gu
Abstract An exploration of the cobalt-tartrate system under hydrothermal conditions, has led to the isolation of crystalline framework {Co2(H2tar)2]·2H2O}n (1) (H2tar = tartrate dianion). Single-crystal X-ray analyses reveal that it crystallizes in the orthorhombic space group P21212. a = 11.0924(11) Å, b = 7.8517(8) Å, c = 9.0171(9) Å, , = 90°. A dinuclear CoII unit is formed via two different coordinated tartrate molecules. Further these units are united together through two bridging carboxylate groups of hexa-coordinated H2tar ligands to form a 2D grid layer, which exhibits a typical (6,3) topological network. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Synthesis, characterization and crystal structure of a porous crystalline material

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2008
Chun-Sheng Zhou
Abstract An exploration of the nickel-malate-bpp system under hydrothermal conditions, has led to the isolation of a novel framework {[Ni(Hmal)(bpp)]·5H2O}n (1) (Hmal = malate dianion, bpp = 1,3-bi(4-pyridyl)propane). Single-crystal X-ray analyses reveal that it crystallizes in the orthorhombic space group Pccn. a = 21.141(3) Å, b = 10.4028(16) Å, c = 19.250(3) Å. The Ni(II) ions are linked into an extended helical chain via Hmal molecules. Further these chains are united together through the bridging bpp to form a 3D porous framework, which exhibits an unusual NbO-type topological network. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Synthesis, characterization and crystal structure of a novel 2D Ni(II) complex with malate

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2008
Weiping Wu
Abstract An exploration of the nickel- malate-bpa system under hydrothermal conditions, has led to the isolation of a novel framework {[Ni(Hmal)(bpa)]·2.5H2O}n (1) (Hmal = malate dianion, bpa = 1,2-bi(4-pyridyl)ethane). Single-crystal X-ray analyses reveal that it crystallizes in the orthorhombic space group Fdd2. a = 21.9944(13) Å, b =33.3369(19) Å, c = 10.3969(5) Å, , = 90°. The NiII ions are linked into an extended helical chain via Hmal molecules. Further these chains are united together through the bridging bpa to form a 2D grid layer, which exhibits a typical (6,3) topological network. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Reactivity of Cationic Lanthanide(III) Monoporphyrinates towards Anionic Cyanometallates , Preparation, Crystal Structure, and Luminescence Properties of Cyanido-Bridged Di- and Trinuclear d,f Complexes

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 22 2008
Xunjin Zhu
Abstract The metathesis reaction between two equivalents of [Ln(tpp)(H2O)3]Cl (Ln = Yb, Er; tpp2, = tetraphenylporphyrinate dianion) and one equivalent of cyanometallate in dmf at room temperature under nitrogen for 24 hours gave the cyanido-bridged d,f trinuclear complexes [{Ln(tpp)(dmf)n}2{(,-NC)2M(CN)2}] (Ln = Yb, n = 2, M = Ni, 1; Ln = Er, n = 3, M = Ni, 2; Ln = Yb, n = 2, M = Pt, 3; Ln = Er, n = 3, M = Pt, 4), a trinuclear complex [{Er(tpp)(dmf)2}{(,-NC)2Fe(CN)4}{Er(Htpp)(dmf)2}] (5), and a dinuclear complex [{Er(tpp)(dmf)(H2O)}(,-NC)Ag(CN)] (6) when the cyanometallate used was the dianion [M(CN)4]2, (M = Ni, Pt), the trianion [Fe(CN)6]3,, and monoanion [Ag(CN)2],, respectively. The solid-state structures of these complexes were ascertained by X-ray crystallography. Photoluminescence studies of complexes 1,4 showed that these complexes displayed photophysical properties characteristic of normal metal,porphyrinato complexes. Their absorption bands and emission peaks in the visible region are typical of the intraligand ,,,* transitions of the porphyrinato ligand. Furthermore, these complexes also exhibited emission characteristic of the lanthanide(III) ion in the near-infrared (NIR) region, which was quenched by the cyanometallates. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

Novel 1,2-Dicarba- closo -dodecaborane(12) Derivatives of Selenium

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2007
Bernd Wrackmeyer
Abstract Lithiation of 1,2-dicarba- closo -dodecaborane(12) (1) followed by insertion of selenium into both C,Li bonds leads to the 1,2-diselenolato-1,2-dicarba- closo -dodecaborane(12) dianion (3), which is converted by oxidative coupling into the cyclic eight-membered bis(diselane) 4 with annellated carborane moieties. Oxidative addition of 4 to ethenebis(triphenylphosphane)platinum(0) gives the bis(triphenylphosphane)platinum(II) complex 7, which contains a chelating 1,2-diselenolato-1,2-dicarba- closo -dodecaborane(12) ligand, by symmetric cleavage of the eight-membered ring in 4 and displacement of ethene. The molecular structures of 4 and 7 were determined by X-ray analysis. The solution-state structures of the new compounds are supported by multinuclear NMR data (1H, 11B, 13C, 29Si, 31P, 77Se, 195Pt). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Reactions of Aminobis(phenolate)-Supported Dioxidotungsten(VI) and Dioxidomolybdenum(VI) Complexes

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 14 2006
Ari Lehtonen
Abstract The dioxidotungsten(VI) and -molybdenum(VI) complexes [WO2(O2NOMe)] (1), [MoO2(O2NOMe)] (2) and [{MoO2(O2NMe)}2] (3) [O2NOMe methoxyethylamino- N,N -bis(2-methylene-4,6-dimethylphenolate) dianion, O2NMe = methylamino- N,N -bis(2-methylene-4,6-dimethylphenolate) dianion] can react with chloride sources (Me3SiCl, SOCl2) to form resultant monooxido dichloro compounds [WOCl2(O2NOMe)] (4), [MoOCl2(O2NOMe)] (5) and [MoOCl2(O2NMe)] (6), respectively. The reaction of tungsten complex yields of the mixture of cis - 4 and trans - 4, which can be separated and characterized. The reactions of analogous molybdenum complexes with Me3SiCl yield trans isomers of 5 and 6 as individual products. Reaction of dioxidotungsten complex 1 with isopropyl isocyanate was found to produce a tungsten(VI) complex [W(O2NOMe)(N- iPr)(L)] (7) (L = N,N,-diisopropylureate) with a terminal imido group and a bidentate ureate ligand. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Syntheses, Crystal Structures and Magnetic Properties of Carboxylato-Bridged Polymeric Networks of MnII

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2006
Subal Chandra Manna
Abstract Three new carboxylato-bridged polymeric networks of MnII having,molecular formula [Mn(ox)(dpyo)]n (1), {[Mn2(mal)2(bpee)(H2O)2]·0.5(bpee)·0.5(CH3OH)}n (2) and {[Mn3(btc)2(2,2,-bipy)2(H2O)6]·4H2O}n (3) [dpyo, 4,4,-bipyridine N,N,-dioxide; bpee, trans -1,2 bis(4-pyridyl)ethylene; 2,2,-bipy, 2,2,-bipyridine; ox = oxalate dianion; mal = malonate dianion; btc = 1,3,5-benzenetricarboxylate trianion] have been synthesized and characterized by single-crystal X-ray diffraction studies and low temperature magnetic measurements. Structure determination of complex 1 reveals a covalent bonded 2D network containing bischelating oxalate and bridging dpyo; complex 2 is a covalent bonded 3D polymeric architecture, formed by bridging malonate and bpee ligands, resulting in an open framework with channels filled by uncoordinated disordered bpee and methanol molecules. Whereas complex 3, comprising btc anions bound to three metal centers, is a 1D chain which further extends its dimensionality to 3D via - and H-bonding interactions. Low temperature magnetic measurements reveal the existence of weak antiferromagnetic interaction in all these complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

One-Dimensional Oxalato-Bridged Metal(II) Complexes with 4 - Amino-1,2,4-triazole as Apical Ligand

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 21 2005
Urko García-Couceiro
Abstract The synthesis, chemical characterization, thermal behavior and magnetic properties of six new one-dimensional oxalato-bridged metal(II) complexes of formula [M(,-ox)(4atr)2]n [MII = Cu (1), Ni (2), Co (3), Zn (4), Fe(5)] and [Cd(,-ox)(4atr)2(H2O)]n (6) (ox = oxalato dianion, 4atr = 4-amino-1,2,4-triazole) are reported. The crystal structures of 1 and 6 have been solved by single-crystal X-ray diffraction, whereas the remaining compounds have been studied by means of X-ray powder diffraction methods. Compounds 1,5 are isomorphous and crystallize in the triclinic space group P1¯ with unit cell parameters for 1 of a = 5.538(1) Å, b = 7.663(1) Å, c = 7.711(2) Å, , = 62.21(1)°, , = 73.91(1)°, , = 86.11(1)°, and Z = 1. The crystal structures are comprised of one-dimensional linear chains in which the trans -[M(4atr)2]2+ units are sequentially bridged by bis(bidentate) oxalato ligands, resulting in an octahedral O4N2 donor set. Cryomagnetic susceptibility measurements show the occurrence of antiferromagnetic intrachain interactions for 2, 3, and 5, whereas compound 1 exhibits a weak ferromagnetic coupling in agreement with the out-of-plane exchange pathway involved. The magnetic behavior of 1 and 2 is analyzed and discussed in the light of the available magneto-structural data for analogous systems. CdII complex crystallizes in the monoclinic space group C2/c with unit cell parameters of a = 16.128(2) Å, b = 6.757(1) Å, c = 11.580(2) Å, , = 104.46(1)°, and Z = 4. Its crystal structure contains one-dimensional chains in which metal centers are heptacoodinated to four oxygen atoms from two symmetry-related bis(bidentate) oxalato bridges, two endocyclic nitrogen atoms of trans -coordinated triazole ligands and one water molecule, to give a CdO4OwN2 pentagonal-bipyramidal geometry. Thermoanalytical and variable-temperature X-ray powder diffraction analyzes show that compound 6 undergoes a reversible dehydration,hydration process in which the anhydrous residue crystallizes with a different crystal lattice retaining the dimensionality of the oxalato,metal framework. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

Bent and Linear Forms of the (,-Oxo)bis[trichloroferrate(III)] Dianion: An Intermolecular Effect , Structural, Electronic and Magnetic Properties

First Examples of Ternary Lanthanide 2,2,-Diphenyldicarboxylate Complexes: Hydrothermal Syntheses and Structures of Lanthanide Coordination Polymers of 2,2,-Diphenyldicarboxylic Acid and 1,10-Phenanthroline

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2003
Yibo Wang
Abstract In the four new lanthanide coordination polymers {[La2(2,2,-dpdc)3(phen)(H2O)]·2H2O}n (1), [Eu2(2,2,-dpdc)3(phen)(H2O)2]n (2), {[Ln2(2,2,-dpdc)3(phen)2(H2O)2]·4H2O}n [Ln = Tb (3), Yb (4)] (2,2,-dpdc = 2,2,-diphenyldicarboxylate, phen = 1,10-phenanthroline), prepared by hydrothermal synthesis, the 2,2,-dpdc dianion affords tetradentate, pentadentate, and hexadentate coordination modes. Complex 1 is a two-dimensional network of infinite 1-D chains assembled through ,,, interactions, with nine- and ten-coordinate La3+, and arranged in wave-like layers. In 2, Eu3+ possesses nine- and ten-coordinate geometries bridged by 2,2,-dpdc ligands to give a 3-D structure. The isomorphous complexes 3 and 4, in which Tb3+ and Yb3+ ions are both nine-coordinate, have two-dimensional structures of 1-D zigzag chains stacked via hydrogen bonds and ,,, interactions of phen molecules. The high-resolution emission spectrum of 2 shows two Eu3+ ion sites, which is consistent with the results of the X-ray crystal structure analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

Synthesis and Structure of Two New High Nuclearity Ru/Pt Mixed-Metal Clusters

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 7 2003
Brian F. G. Johnson
Abstract The reaction of the dianion [Ru5C(CO)14]2, with [PtCl2(MeCN)2] in the presence of silica yields [Ru5PtC(CO)16] (1) and the new compound [PPN]2[Ru10Pt2C2(CO)28] (2), while, in a related reaction, [Ru6C(CO)16]2, undergoes addition of [PtCl2(MeCN)2] to yield the cluster [Ru12PtC2(CO)32(MeCN)2] (3). The high nuclearity compounds 2 and 3 have been fully characterized and their structures determined by single crystal X-ray analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

Total Synthesis of Silyl-Protected Early Intermediates of Polyketide Biosynthesis,

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 16 2010
Karsten Krohn
Abstract The ketal- or dithioketal-protected isocoumarins 15,18 gave the corresponding 1-naphthols 21,26 in their reactions with the acetoacetate (10) or pentane-2,4-dione (19) dianions and the acetone monoanion. Subjection of the dithioketal-protected ester 28 to Baker,Venkataraman reaction conditions led to the 8-deoxy tautomeric, protected forms 29/30 of the early decaketide antibiotic intermediate 2b. However, the dithioketal protecting groups could not be removed without destruction of the molecule. Consequently the silyl-protected unstable early tri- and tetracyclic decaketide biosynthesis intermediates 37a, 37b, and 38a (precursors of angucycline and anthracycline antitumor antibiotics) were prepared through silylation of 33a and 33b, to afford 34a and 34b, and subsequent treatment with acetylacetone dianion. The ultimate synthetic goal, the silyl-protected 2,3-dialkylated naphthol derivative 41, was achieved by selective elongation of the bottom chain of the bis-silyl-protected methyl ester 36 with acetylacetone dianion. [source]

Elimination Mechanisms in the Aminolysis of Sulfamate Esters of the Type NH2SO2OC6H4X , Models of Enzyme Inhibitors

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2008
William J. Spillane
Abstract The kinetics of the reaction of 4-nitrophenyl sulfamate NH2SO2OC6H4NO2 -4 (1a) in acetonitrile (ACN) with a series of pyridines (pKa range ca. 8 units) and alicyclic amines (pKa range ca. 3.6 units) has been studied in the presence of excess amine at various temperatures. The compounds 1a,1f are important as model substrates for the medicinally important sulfamate esters 667-coumate and emate and analogues. Pseudo-first-order rate constants (kobsd.) have been obtained mainly by the release of 4-nitrophenol/4-nitrophenoxide. Slopes of plots of kobsd. vs. [amine] gave second-order rate constants (k2), and Brönsted plots were biphasic for the aminolysis (with alicyclic amines) with an initial slope ,1 = 0.53 and a subsequent slope ,2 = 0.19. The change in slope occurs near the first pKa of 1a (17.9) in ACN. Leaving-group effects were probed by using the same series of phenyl sulfamates, i.e. 1a,f and the alicyclic amines N -formylpiperazine and pyrrolidine. The reactions were considered to be dissociative in nature involving E2- and E1cB- type mechanisms with the phenyl sulfamate anion 2 being involved in pyridine and in the weaker alicyclic amines (,1 segment) and a phenyl sulfamate dianion 3 being involved with the stronger alicyclic bases (,2 segment). The calculation of Leffler indices (,) for bond-forming (base···H+) and bond-breaking (S,OAr) steps allows fuller interpretation of the mechanisms occurring, which are seen as having the N -sulfonylamines, HN=SO2 and ,N=SO2 on the reaction pathways leading to products. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

Efficient Routes to Acenaphthylene-Fused Polycyclic Arenes/Heteroarenes and Heterocyclic Fluoranthene Analogues

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 10 2005
Kausik Panda
Abstract The acenaphthenone-derived , -oxoketene dithioacetal 2 has been subjected to various [3 + 3] aromatic and heteroaromatic annulation and other heterocyclization reactions previously developed in our laboratory, providing short and efficient routes to a diverse range of known and unknown acenaphtho-annulated linear and angular PAHs, heteroaromatics and five-membered heterocycles in good yields. Thus, benzo- and naphthoannulation of 2 with various allyl and benzyl Grignard reagents afforded substituted fluoranthenes 4a,c and benzo[k]fluoranthene 8, respectively, in good yields. Similarly, the parent benzo[j]fluoranthene 15a and its substituted derivative 16b have been synthesized by base-induced conjugate 1,4-addition of arylacetonitriles to 2, followed by acid-induced cyclization of the conjugate adducts 12a,b to give 13a,b and subsequent further transformations. The adducts obtained by 1,4-addition of anions derived from acetophenone and acenaphthenone were subjected toheterocyclization in the presence of ammonium acetate to give 8-arylacenaphtho[1,2- b]pyridines 18a,b and bis(acenaphtho)-annulated pyridine 20. Heterocyclization of 2 with bifunctional nucleophiles such as 2-picolyllithium and guanidinium nitrate afforded the corresponding acenaphtho[1,2- b]quinolizinium salt 23 and acenaphtho[1,2- d]pyrimidine 24, respectively, in high yields. Finally, acenaphtho[1,2- c]-fused five-membered heterocycles such as 7-(methylthio)acenaphtho[1,2- c]thiophene (25), 7-(methylthio)acenaphtho[1,2- c]furan (27) and 7-(methylthio)acenaphtho[1,2- c]pyrrole-2-carboxylic acid (30) were obtained in good yields by subjection of 2 to Simmons,Smith reaction conditions or by treatment with dimethylsulfonium methylide or glycinate dianion. Some of these newly synthesized PAHs or fused heterocycles were subjected to Raney Ni desulfurization to furnish sulfur-free compounds. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

Tetrakis(trimethysilyl)hypophosphate P2O2(OTMS)4: Synthesis, reactivity and application as flame retardant

HETEROATOM CHEMISTRY, Issue 7 2007
Catherine Ruflin
The preparation of tetrakis(trimethy- silyl)hypophosphate, P2O2(OTMS)4 (TMS = SiMe3), which is easily obtained from cheap starting materials, is reported. Reaction with protic substrates (H2O, alcohols) proceeds under stepwise cleavage of silylethers, ROTMS, and formation of hypophosphoric acid, P2O2(OH)4. Amines in the presence of molecular sieves lead to desilylation and formation of ammonium salts of the [P2O2(OTMS)2(O,)2] dianion. On cotton fabrics, P2O2(OTMS)4 hydrolyzes to give P2O2(OH)4 within about 1 h when exposed to air, and this compound acts as an efficient flame retardant (limiting oxygen index >26%) even at low loadings (P content <3%). © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:721,731, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20373 [source]

Synthesis of polyetherols with isocyanuric ring.

INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 8 2009
Kinetics, ethylene carbonate, mechanisms of reactions, part 1: Reaction between isocyanuric acid
The reaction between isocyanuric acid and ethylene carbonate results in the formation of polyetherols. The kinetic and mechanistic studies revealed that the initial step of the reaction is zero order related to ethylene carbonate. The rate-limiting step is the decomposition of an intermediating dianion of ethylene dicarbonate into ethane-1,2-diolate dianion and carbon dioxide. Imide groups of isocyanuric acid inhibit the reaction. The mechanism of reaction was confirmed by spectroscopic methods. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 512,522, 2009 [source]

A facile synthesis of substituted 3-amino-1H -quinazoline-2,4-diones

JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2005
Tuan P. Tran
A new synthesis of a series of 3-amino-1H -quinazoline-2,4-diones is described. The 1H -quinazoline-2,4-dione 10 was made starting with fluorobenzoic acid in three high yielding steps. The key step of this synthesis involved the generation of the dianion of urea 7 and the subsequent intramolecular nucleophilic displacement of the 2-fluoro to form the quinazolinedione ring. The 3-amino moiety was incorporated using (2,4-dinitro-phenyl)-hydroxylamine as the aminating reagent. [source]

Raman spectra of a pseudo-oxocarbon anion in ionic liquids

JOURNAL OF RAMAN SPECTROSCOPY, Issue 5 2010
Humberto C. Garcia
Abstract Raman and electronic spectra of the [3,5-bis(dicyanomethylene)cyclopentane-1,2,4-trionate] dianion, the croconate violet (CV), are reported in solutions of ionic liquids based on imidazolium cations. Different normal modes of the CV anion, , (CO), , (CO) + , (CC) + , (CCN), and ,(C,N), were used as probes of solvation characteristics of ionic liquids, and were compared with spectra of CV in common solvents. The spectra of CV in ionic liquids are similar to those in dichloromethane solution, but distinct from those in protic solvents such as ethanol or water. The UV,vis spectra of CV in ionic liquids strongly suggest ,,, interactions between the CV anion and the imidazolium cation. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Polymorphism in the spin-crossover ferric complexes [(TPA)FeIII(TCC)]PF6

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 4 2009
Eric Collet
We have identified two polymorphs of the molecular complex [(TPA)Fe(III)(TCC)]PF6 [TPA = tris(2-pyridylmethyl)amine and TCC = 3,4,5,6-tetrachlorocatecholate dianion]: one is monoclinic and the other is orthorhombic. By lowering the temperature both undergo a thermal spin-crossover between a high-spin (S = 5/2) and a low-spin (S = 1/2) state, which we detected by magnetic, optical and X-ray diffraction measurements. The thermal crossover is only slightly shifted between the polymorphs. Their crystalline structures consist of similar cation layers alternating with PF6 anion layers, packed differently in the two polymorphs. The magnetic and optical properties of the polymorphs are presented. [source]

Hexaaquanickel(II) disulfato(1,4,8,11-tetraazacyclotetradecane)nickelate(II) dihydrate

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2010
Andrew James Churchard
The title compound, [Ni(H2O)6][Ni(SO4)2(C10H24N4)]·2H2O, is an unusual compound in that it is composed of a hexaaqua complex, formally a dication, and a mixed-donor complex (four N and two O atoms), formally a dianion, with substantial charge separation between the two nickel centres (6.536,Å). The homoleptic dication complex consists of the weaker-field ligands, whilst the dianion retains the coordination of all the higher-field donors. Both nickel ions are located at centres of symmetry. This rare compound is placed in the context of previously reported structures which emphasizes its peculiarity. [source]