Hypervalence and the delocalizing versus localizing propensities of H 3– , Li 3– , CH 5– and SiH 5–

Lithium and silicon have the capability to form hypervalent structures, such as Li₃^– and SiH₅^–, which is contrasted by the absence of this capability in hydrogen and carbon, as exemplified by H₃^– and CH₅^– which, although isoelectronic to the former two species, have a distortive, bond-localizing propensity. This well-known fact is nicely confirmed in our DFT study at BP86/TZ2P. We furthermore show that the hypervalence of Li and Si neither originates from the availability of low-energy 2p and 3d AOs, respectively, nor from differences in the bonding pattern of the valence molecular orbitals; there is, in all cases, a 3-center-4-electron bond in the axial X–A–X unit. Instead, we find that the discriminating factor is the smaller effective size of C compared to the larger Si atom, and the resulting lack of space around the former. Interestingly, a similar steric mechanism is responsible for the difference in bonding capabilities between H and the effectively larger Li atom. This is so, despite the fact that the substituents in the corresponding symmetric and linear dicoordinate H₃^– and Li₃^– are on opposite sides of the central atom. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.

Die halbquantitative Bestimmung von Cl?, Br?, J?, SCN?, AsO43?, Cr2O72? und [Fe(CN)6]3?

Ohne Zusammenfassung     

Zum schnellen Nachweis der Kationen Cu++, Ni++, Co++, Fe++ und Mn++, der AnionenSCN?,OCN?,CN?,S2O82?,J?und Br? sowie tert.aliphatischer Amine und Pyridine

Ohne Zusammenfassung     

Die quantitative Trennung der Halogenide Cl?, Br? und J? durch Ionenaustauscn-Chromatographie

Ohne Zusammenfassung     

Bestimmung von Halogenidionen (Cl?, Br?, J?) in Halogenidgemischen

Zusammenfassung Es wird über eine Methode zur Bestimmung von Halogenidionen in Halogenidgemischen berichtet. Die Endpunktindikation erfolgt nach dem Prinzip der Polarisationsspannungstitration und liefert scharf ausgeprägte Titrationsendpunkte in der Reihenfolge der Schwerlöslichkeit der Ag-Halogenide. Insbesondere wird auch der für Serienanalysen erforderlichen Einfachheit und geringen Störanfälligkeit Rechnung getragen. Das Verfahren eignet sich für die Analyse anorganischer Halogenidgemische, für die Bestimmung von CN^–- und SCN^– -Ionen und für die Analyse organischer Halogenverbindungen im Makro- und Halbmikromaßstab nach deren Aufschluß. Die Meßanordnung kann außerdem für die Bestimmung von Kalium und für die Endpunktindikation einiger chelatometrischer Titrationen eingesetzt werden.

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Summary A method is described for the determination of halogenide in mixtures of halogenides. End points are sharply indicated by the polarisation titration technique in the order of solubility of the silver halogenides. The method is suitable for the analysis of mixtures of inorganic halogenides, for the determination of CN^– and SCN^–ions, and for the analysis of organic halogen compounds in macro and semimicro scale after decomposition. For routine analyses it offers the advantage of being simple and only slightly liable to interferences. Moreover, the assembly can be used for the determination of potassium and for the end point indication in some chelatometric titrations.

     

Ionophoretische Trennung von ReCl62?, ReBr62? und ReO4?

Zusammenfassung Es wurde die ionophoretische Trennung von ReCl₆ ^2–, ReBr₆ ^2– und ReO₄ ^– unter Verwendung verschiedener Papiersorten untersucht. Am geeignetsten erwies sich das Papier 2045 b Gl von Schl. & Sch.

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Summary The ionophoretic separation of ReCl₆ ^2–, ReBr₆ ^2–, and ReO₄ ^– has been examined using different kinds of paper. Best results have been obtained with the paper 2045 b Gl from Schleicher & Schüll.

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Herrn Prof. G. Brauer danke ich für Förderung. Für die Überlassung von Rheniumverbindungen bin ich der Fa. W. C. Heraeus, Hanau, verpflichtet. Die Neutronenaktivierung wurde freundlicherweise von den Herren Dr. Marth und Dr. Köhler von der Reaktorstation in Garching bei München vorgenommen. Das Bundesministerium für Atomkernenergie und Wasserwirtschaft unterstützte die Untersuchung durch eine Sachbeihilfe.     

Eine titrimetrische Bestimmung von ClO?, ClO2? und ClO3? aus einer Probe

Ohne Zusammenfassung     

Modification of supramolecular assemblies based on C4H7(CH3)Te heterocycle and cooperative participation of intermolecular I···I, Te···I, Te···O secondary bonds; C(sp3)–H···O and C(sp2)–H···O hydrogen bonds

2-Methyl-1,1-dicarboxylato-1-telluracyclopentanes C₄H₇(CH₃)Te(OCOR)₂ (R=OCO, C₆H₅, 4-NO₂C₆H₄, 3,5-(NO₂)₂C₆H₃, C₆H₅CH=CH, 4-OCH₃C₆H₄) (2–7) were synthesised from the reactions of 2-methyl-1,1-diiodo-1-telluracyclopentane (1) and corresponding silver salts and characterised by (IR &¹HNMR) spectroscopy. The structures of C₄H₇(CH₃)TeI₂ (1), C₄H₇(CH₃)Te(OCOC₆H₅)₂ (3) and C₄H₇(CH₃)Te(4-NO₂C₆H₄OCO)₂ (4) were established by single crystal X-ray diffraction studies. The structures of 1, 3 & 4 (the immediate environment about tellurium is that of distorted trigonal bipyramidal geometry with a stereochemically active electron lone pair) are described in the context of their ability to generate intermolecular I···I, Te···I, Te···O secondary bonds; C(sp³)–H···O and C(sp²)–H···O hydrogen bonds leading to the formation of polymeric, tetrameric and trimeric supramolecular assemblies. The modification of supramolecular assembly present in the precursor 1 is demonstrated and the cooperative participation of C(sp²)–H···O & C(sp³)–H···O hydrogen bonds, probably, helpful in strengthening the supramolecular assembly is discussed.

Multiple-layer heterometallic MnII–AgI coordination polymers constructed from [Ag 2I (CN)3]? and [AgI(CN)2]? units

Two multiple-layer heterometallic Mn^II–Ag^I coordination polymers, {Mn^II(ampyz)(H₂O)[Ag₂^I(CN)₃][Ag^I(CN)₂]·ampyz} _n (1) and {[Mn^II(benzim)₂[Ag^I(CN)₂]₂][(benzim)Ag^I(CN)]·H₂O} _n (2) where ampyz = 2-aminopyrazine and benzim = benzimidazole, have been prepared and structurally characterized. Compound 1 reveals a multiple-layer two-dimensional network with strong hexanuclear argentophilic interactions leading to an infinite three-dimensional framework. Compound 2 has an unprecedented double-layer two-dimensional squared grid-type network with (4,4) topology through Ag^I···Ag^I and π–π interactions between two adjacent squared layers. These double-layer networks of 2 are linked to others by π–π interactions, leading to a three-dimensional framework.     

Polyatomic anion versus acetonitrile in coordinating ability: structural properties of AgX-bearing 1,4-bis(2-isonicotinoyloxyethyl)piperazine (X??=?NO3?, CF3SO3?, ClO4?, BF4?, and PF6?)

Type studies on competitive polyatomic anion versus acetonitrile coordination in the self-assembly of a series of [Ag₂(X) _m (bip)(NCCH₃) _n ](X)_2−m (X⁻ = NO₃ ⁻, CF₃SO₃ ⁻, ClO₄ ⁻, BF₄ ⁻, and PF₆ ⁻; m = 0, 2; n = 0, 2, 4; bip = 1,4-bis(2-isonicotinoyloxyethyl)piperazine) were carried out. Each bip spacer acts as an N₄ tetradentate ligand and is linked to four silver(I) centers through two pyridine and two piperazine moieties, producing a double strand consisting of two 20-membered ring units. The coordinating environment around the silver(I) center is subtly determined by the competition of the polyatomic anions with acetonitrile, that is, by the Ag···NCCH₃ versus Ag···X interactions. The coordinating ability of acetonitrile is inversely proportional to the order of the coordination ability of the Hoffmeister series of polyatomic anions, NO₃ ⁻ ≫ CF₃SO₃ ⁻ > ClO₄ ⁻ > BF₄ ⁻ ≫ PF₆ ⁻.     

Crystal structure of C17H20FN3O 32+ ·CuBr 42? ·H2O

A new compound C₁₇H₂₀FN₃O₃²⁺·CuBr₄²⁻·H₂O is synthesized in the crystal form, where C₁₇H₁₈FN₃O₃ (CfH, ciprofloxacin) is 4-oxo-7-(1-piperazinyl)-6-fluoro-1-cyclopropyl-1,4-dihydroquinoline-3-carboxylic acid. Crystallographic data of ciprofloxacinium tetrabromocuprate(II) monohydrate, C₁₇H₂₂Br₄CuFN₃O₄: a = 8.214(1) ?, b = 10.781(2) ?, c = 13.703(2) ?, α = 85.144(2)°, β = 79.119(2)°, γ = 84.018(2)°, V = 1182.5(4) ?³, P [`1]\bar 1 space group, Z = 2. Supramolecular architecture of the crystal differs from that established for C₁₇H₂₀FN₃O₃²⁺·CuCl₄²⁻·H₂O by the absence of π-π interactions of the aromatic rings of CfH₃²⁺ ions and also the structural motifs formed by intermolecular hydrogen bonds.     

Structure of the C17H20FN3O 32+ ·2HSO 4? · H2O compound

A new compound of C₁₇H₂₀FN₃O₃²⁺ · 2HSO₄⁻·H₂O [ciprofloxacindi-um bis(hydrosulfate) monohydrate], C₁₇H₁₈FN₃O₃ 1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinolinecarboxylic acid (CfH, ciprofloxacin) is obtained and its crystal structure is determined. The crystal contains CfH₃²⁺ and HSO₄⁻ ions and crystallization water molecules. Hydrogen (H3), which forms an intramolecular hydrogen bond with oxygen O2 of the carboxyl group, is attached to the carbonyl O1 atom. Hydrogen H4 of the carboxyl group is hydrogen bonded to the crystallization water molecule which links CfH₃²⁺ with two HSO₄⁻ groups by hydrogen bonds. Both H atoms at N3 of the piperazine ring form hydrogen bonds with two oxygen atoms of other HSO₄⁻ anions. Intramolecular hydrogen bonds of two types are present in the CfH₃²⁺ cation. One of them forms a six-membered ring, bonding O1 and O2 atoms, while the other, also enclosing a six-membered ring, links fluorine and carbon C14 atoms. Original Russian Text Copyright ? 2009 by A. D. Vasiliev, N. N. Golovnev, and I. A. Baidina __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 1, pp. 165–168, January–February, 2009.     

Modeling Ar and Kr matrix effect on the ν s (Cl–H) and ν l (Cl–H) of Cl–H···NH3 by the IEF-PCM method

Ar and Kr matrix effect on the geometry and Cl–H stretching (ν _s (Cl–H)) and librational (ν _l (Cl–H)) frequencies of the hydrogen-bonded complex Cl–H···NH₃ are simulated within the framework of polarizable continuum model with integral equation formalism (IEF-PCM) at B3LYP and MP2 levels of theory with the basis set 6-311++G(2df,2pd). Within the framework of B3LYP and IEF-PCM, the simulated gas phase, Ar, and Kr matrix ν _s (Cl–H) of the complex are 2140, 1684, and 1550 cm⁻¹, respectively, which deviate from the experimental values (~2200, 1371, and 1218 cm⁻¹) by −60, 313, and 332 cm⁻¹. Within the framework of MP2 and IEF-PCM, the gas phase, Ar, and Kr matrix ν _s (Cl–H) are calculated as 2366, 2037, and 1957 cm⁻¹ by the harmonic approximation, and as 2177, 1876, and 1665 cm⁻¹ by the full-dimensional anharmonic correction. The matrix effect modeling is of greater importance than the anharmonic correction in accounting for the large experimental gas phase to Ar or Kr matrix shift of the ν _s (Cl–H) (−829 or −982 cm⁻¹). Our calculations do not support the assignment of the 733.8 and 736.9 cm⁻¹ bands to the Ar and Kr matrix ν _l (Cl–H).     

Unactivated C(sp3)–H functionalization via vinyl cations

Direct functionalization of inert C(sp³)–H bonds is a topic of immense contemporary interest and exceptional value in organic synthesis.The recent research has established a novel and practical protocol which features the engagement of vinyl cation species to functionalize C(sp³)–H bonds.The discussion of the topic is arranged by the strategies to generate the reactive intermediates,including ionization of vinyl triflates,addition of electrophiles to alkynes,tandem cyclization of enynes or diynes,and decomposition ofβ-hydroxy-α-diazo ketones.This review closes with a personal perspective on the dynamic research area of unactivated C(sp³)–H functionalization via vinyl cations.Hopefully,it will provide timely illumination and beneficial guidance for organic chemists who are interested in this area.Meanwhile continued development of the field is strongly anticipated in the future.     

Salt effects in the reaction between IrCl62? and MnEDTA2?

The oxidation of MnEDTA^2–. (EDTA=ethylenediaminetetra-acetate) by hexachloroiridate(IV) has been studied in concentrated electrolyte solutions at 298 K. The estimation of the activity coefficients of the species from the Stokes-Robinson hydration theory indicates that the observed salt effects have their origin in a greater destabilization of the initial state with respect to the transition state when increasing salt concentration. MnEDTA^2– (EDTA= ) (IV) . -, , .     

Crystal structure of [MnII (1,10-C12H8N2)3]2+[(B9C2H11)CoIII(B8C2H10)CoIII(B9C2H11)]2?·CH3CN

A novel compound, [MnPhen₃][(B₉C₂H₁₁)Co(B₈C₂H₁₀)Co(B₉C₂H₁₁)]· CH₃CN (Phen = 1,10-phenantroline), comprising a Co(III) dicobaltacarborane cluster anion has been prepared and characterized by single crystal X-ray diffraction. Crystal data are the following: C₄₄H₅₉B₂₆N₇Co₂Mn, M = 1139.84, triclinic, space group , unit cell parameters: a = 13.2465(11) Å, b = 14.521(2) Å, c = 15.2536(15) Å; α = 77.027(9)°, β = 88.500(8)°, γ = 77.274(9)°; V = 2788.5(5) ų, Z = 2, d _calc = 1.358 g/cm³, T = 295 K, F(000) = 1162, μ = 0.853 mm⁻¹. The structure was solved by the direct and Fourier methods and refined anisotropically (isotropically for hydrogen atoms) using the full-matrix technique to final factors R ₁ = 0.0374, wR ₂ = 0.0915 for 7397 I _hkl ≥2σ_I of 9779 I _hkl measured (diffractometer Enraf-Nonius CAD-4, λMoK _α , graphite monochromator, θ/2θ-scanning). The structure is formed from [MnPhen₃]²⁺ cations, [(B₉C₂H₁₁)×Co(B₈C₂H₁₀)Co(B₉C₂H₁₁)]₂₋ anions, and acetonitrile molecules CH₃CN. Central Mn atom in the cation has a distorted octahedral coordination environment formed by six nitrogen atoms of three bi-dentate Phen ligands, average Mn-N bond length being 2.263(2) Å. The anion has a chain-like structure built from three icosahedra sharing common vertices occupied by the cobalt atoms. The central icosahedron including ten light atoms (8B, 2C) provides two vertices for the cobalt atoms shared with the other icosahedra having 11 light atoms (9B, 2C). The arrangement of-C₂-groups in the anion corresponds to a quasi-gauche-configuration of asymmetric sandwich complexes of both cobalt atoms. Original Russian Text Copyright ? 2005 by T. M. Polyanskaya, V. V. Volkov, and M. K. Drozdova __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 46, No. 4, pp.730–740, July–August, 2005.     

Kinetic model for the Bray-Liebhafsky process without the reaction IO3?+I?+2H+?HIO+HIO2

Oscillations in the concentration of intermediates were obtained when a model without reaction IO ₃ ^– +I^–+2H⁺HIO+HIO₂ was used for the simulation of the Bray-Liebhafsky process.     

Crystal structure of pefloxancindium tetrabromidozinkate C17H22FN3O 32+ · ZnBr 42?

A new compound, namely pefloxancindium tetrabromidozincateC₁₇H₂₂FN₃O₃²⁺ · ZnBr₄²⁺ where C₁₇H₂₀FN₃O₃ is 1-ethyl-N-methyl-6-fluoro-1,4-dihydro-4-oxo-7-(4-methyl-1-piperazinyl)-3-quinoline carboxylic acid (PefH, pefloxacin), has been synthesized and its crystal and molecular structure has been solved. It contains PefH₃²⁺ and ZnBr₄²⁻ ions. The latter is a slightly distorted tetrahedron. The supramolecular architecture of a crystal has been analyzed.     

Bismuth compounds [Ph3BuP]+I?, [Ph3BuP] 2+ [Bi2I8 · 2Me2C=O]2?, and [Ph3BuP] 2+ [Bi2I8 · 2Me2S=O]2?: Syntheses and crystal structures

The complexes [Ph₃BuP]₂⁺[Bi₂I₈ · 2Me₂C=O]²⁻ (II) and [Ph₃BuP]₂⁺[Bi₂I₈ · 2Me₂S=O]²⁻ (III) are synthesized by the reactions of triphenyl(n-butyl)phosphonium iodide (I) with bismuth iodide in acetone and dimethyl sulfoxide. In the cations of complexes I–III, the P atoms have a distorted tetrahedral coordination (CPC angles 106.3(2)°–112.0(3)°). The butyl group in cation I is disordered over two positions. In the binuclear centrosymmetric anions of structures II and III, the octahedrally coordinated bismuth atoms are linked in pairs by two bridging (br) iodine atoms (Bi-I_br 3.1508(7) and 3.2824(8) ? in compound II, 3.1961(3) and 3.3108(3) ? in complex III), which are coplanar to four terminal (t) iodine atoms (Bi-I_t 2.9260(7) and 2.9953(6) ? in complex II, 2.9206(3) and 2.9786(3) ? in complex III). The two remaining positions at the bismuth atom are occupied by the iodine atom (Bi-I_t 2.8531(7) ? in complex II, 2.8984(3) ? in complex III) and O atom of the organic molecule (Bi-O 2.747(6) ? in complex II, 2.507(3) ? in complex III). Original Russian Text ? V.V. Sharutin, I.V. Egorova, N.N. Klepikov, E.A. Boyarkina, O.K. Sharutina, 2009, published in Koordinatsionnaya Khimiya, 2009, Vol. 35, No. 3, pp. 188–192.