Protonation of Ferrocene in the Gas Phase

Hydrogen-deuterium exchange, proton and deuteron transfer, and collision-induced dissociation experiments involving protonated ferrocene, [Fe(cC₅H₅)₂]H⁺, and isotopically labeled analogues have been carried out using a Fourier transform ion cyclotron resonance (FTICR) spectrometer and a double-focusing mass spectrometer of reversed geometry. These experiments reveal that the structure in which the added proton is bound to one of the cyclopentadienyl rings, possibly via agostic interaction with the iron atom, plays an important role in the gas-phase behavior of protonated ferrocene. It is demonstrated that extensive hydrogen atom scrambling occurs in the cyclopentadiene ring and that the extra hydrogen can also switch from one ring to the other, probably via the iron atom. An interpretation is presented which implicates slow thermal unimolecular rearrangement on the FKR time scale from a metal-protonated form to a ring-protonated form which is higher in energy. This interpretation successfully rationalizes the current data as well as previous gas-phase measurements and is found to be in good agreement with solution and matrix isolation studies.     

Boundary effect on the adsorption properties of H2 on charged MgCaHb complex

In this article, the equilibrium structure, binding energy, and electronic structure for charged Mg coated C_aH_b (a = 6, b = 6; a = 14, b = 10; a = 22, b = 14; a = 24, b = 14; a = 54, b = 18) are investigated by using all electrons density‐functional calculations. The boundary effect for the adsorption property of H₂ on charged MgC_aH_b complex is investigated by using several structures based on benzene ring molecules. A method for calculating the pathways for the synthesis of MgC_aH_bⁿ⁺ is presented here, and also the kinetic stability of these charged hydrogen‐covered MgC_aH_bⁿ⁺ complexes is also discussed. We find that the Mg doped complex with appropriate charge can enhance adsorption of hydrogen molecular. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012     

Synthesis,structure and isomerism of “three-bridge” exo-nido-osmacarborane clusters

The reaction of OsCl₂(PPh₃)₃ with [nido-7-R¹-8-R²-C₂B₉H₁₀]K⁺ produced a series of new exo-nido-osmacarborane complexes exo-nido-5,6,10-[Cl(Ph₃P)₂Os]-5,6,10-(-H)₃-10-H-7-R¹-8-R²-7,8-C₂B₉H₆ (1: R¹ = R² = H; 2: R¹ = R² = Me; 3: R¹ = R² = PhCH₂; 4: R¹ + R² = 1,2-C₆H₄(CH₂)₂; 5: R¹ = H, R² = Me) in which the osmium-containing group is linked to the nido-carborane ligand through three two-electron three-center bonds. Compounds 1—5 are formed as mixtures of symmetric (a) and asymmetric (b) isomers; pure symmetric isomers 2a and 4a were isolated by fractional crystallization, and the mixture of isomers 3a, was quantitatively separated into individual compounds 3a and 3b by column chromatography on silica gel. Detailed analysis of the ³¹P{¹H}, ¹H, ¹¹B NMR spectra of 1a,b—5a,b and 2D ¹H-¹H{¹¹B} and ¹¹B{¹H}-¹¹B{¹H} NMR spectra of 3a and 3b was performed. The structures of isomers 2a and 4a were confirmed by an X-ray diffraction study. According to the NMR and X-ray diffraction data, the isomerism of exo-nido-complexes 1a,b—5a,b is actually the cis—trans-isomerism of ligand arrangement in the octahedral coordination of the Os atom.     

Metal-induced B—H activation in Cp*Rh,Cp*Ir, (p-cymene)Ru,and (p-cymene)Os half-sandwich complexes containing the 1,2-dicarba-closo-dodecaborane(12)-1,2-dichalcogenolato ligand

The reactivity of the 16e half-sandwich complexes Cp*Rh[E₂C₂(B₁₀H₁₀)] (1a,b), Cp*Ir[E₂C₂(B₁₀H₁₀)] (2a,b) (E = S (a), Se(b)), (p-cymene)Ru[S₂C₂(B₁₀H₁₀)] (3), (p-cymene)Os[S₂C₂(B₁₀H₁₀)] (4) (p-cymene = 1-Me-4-Prⁱ-benzene) towards various alkynes (acetylene, propyne, 3-methoxypropyne, methyl acetylenemonocarboxylate, dimethyl acetylenedicarboxylate, phenylacetylene, ferrocenylacetylene) was studied. The reactions start with an insertion into one of the M—E bonds, followed (except for MeO₂C—CC—CO₂Me) by intramolecular, metal-induced B—H activation, formation of an M—B bond, accompanied by simultaneous transfer of a hydrogen atom from boron via the metal atom to the alkyne. This leads to new complexes with a cisoidor transoid geometry (orientation of the E—C=C unit with respect to the C(1)—B bond). This geometry determines the course of further intramolecular reactions which lead selectively to carboranes mono- or disubstituted in B(3,6) positions. Numerous intermediates and final products were characterized by X-ray analysis in the solid state, and by multinuclear magnetic resonance in solution. First catalytic applications of 1a,b became evident by cyclotrimerization reactions.     

Die Synthese von 8-Methoxy-1,2,3,9-tetrahydro-4-fluorenon

The title compound1 is synthesized as follows: Carbethoxylation of5 a and subsequent alkylation yield6 a which is transformed into7 b.7 b is reduced by NaBH₄ to yield the isomeric esters8 a which are subjected to dehydration usingDMSO/H₂SO₄ as dehydrating agent. The resulting2 a is subjected to intramolecular ring closure using sodium hybride as condensating agent. Structural proof for1 is given as well by interpretation of its¹H-NMR-spectrum as by transformation into11 by hydrogenation andWolff—Kishner reaction and synthesis of11 by another unambiguous method which involvesStorck-reaction of5 a to yield12 a, hydrogenation andWolff—Kishner reaction of13.     

Fullerene C60 as a η5- and η6-ligand in sandwich-type π-complexes with transition metals

The molecular and electronic structures of some hypothetical sandwich-type -complexes of transition metals with fullerene C₆₀ were modeled. The M-C₆₀ bonds in ⁵-C₆₀MCp⁺ complexes (M = Fe, Ru, Os) are less strong than the M-Cp bonds in ferrocene, ruthenocene, and osmocene, respectively. The ⁶-C₆₀MC₆H₆ complexes (M = Cr, Mo, W) should be less stable than their classical analogs (C₆H₆)M(C₆H₆). The coordination of a metal atom with the fullerene at its pentagonal face is more energetically favorable than at a hexagonal face.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 598–601, April, 1994.We are grateful to V. I. Sokolov for discussion of the results obtained. This study was supported by the Russian Foundation for Basic Research (grants 93-03-4101 and 93-03-18725).     

Electronic effect of ferrocenyl,ruthenocenyl, and osmocenyl group as substituents

Conclusions According to the¹⁹F NMR spectra of the m- and p-fluorophenyl derivatives of ferrocene, ruthenocene, and osmocene, the inductive component successively increases and the resonance component of the electron-donor effect of the metallocenyl groups successively decreases with increase in the order number of the metal.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1170–1172, May, 1981.     

Reactions of [Re(NO)2(PR3)2][BArF 4] complexes with phenylacetylene

The reaction of [Re(NO)₂(PR₃)₂][BAr^F ₄] (R = cyclo-C₆H₁₃ (1a), Prⁱ (1b); [BAr^F ₄]^– = [B(3,5-(CF₃)₂C₆H₃)₄]) with phenylacetylene in the presence of a non-nucleophilic base, like 2,6-bis(tert-butyl)pyridine (BTBP) or Bu^tOK, affords the phenylethynyl complexes [Re(CCPh)(NO)₂(PR₃)₂] (R = cyclo-C₆H₁₃ (2a); Prⁱ (2b)) in moderate yields. In the absence of a base, complexes 1a and 1b are transformed into the compounds [Re(CCPh)(CH=C(Ph)ONH)(NO)(PR₃)₂][BAr^F ₄] (3a and 3b, respectively). The structure of complex 3a was confirmed by X-ray diffraction analysis. The latter reaction is proposed to be initiated by deprotonation of the terminal alkyne H atom by the bent nitrosyl ligand followed by the subsequent 1,3-dipolar addition of the ReN(H)O moiety to phenylacetylene.     

Two thia­zolino­[2,3-a]­iso­quinolinone S-oxides

The structures of two racemic thia­zolino­[2,3-a]­isoquinolinone S-oxides, i.e. 8,9-di­methoxy-2,3,5,6-tetra­hydro-10bH-thia­zolo­[2,3-a]­isoquinolin-3-one 1-oxide [C₁₃H₁₅NO₄S, (IIa)] and 8,9-di­methoxy-10b-methyl-2,3,5,6-tetra­hydro-10bH-thia­zolo­[2,3-a]­isoquinolin-3-one 1-oxide [C₁₄H₁₇NO₄S, (IIb)], are described. The thia­zolinone ring in (IIa) exists in an envelope conformation, while in (IIb), it assumes a half-chair conformation. In (IIa) and (IIb), the six-membered heterocyclic ring adopts an envelope conformation. The O atom at sulfur is oriented in a pseudo-axial position, whereas the H atom in (IIa) and the methyl group in (IIb), linked to the stereogenic C centre, occupy a bisectional position with respect to the partially saturated pyridine ring and a pseudo-axial position with respect to the thia­zolinone ring. In both structures, the S=O group and the substituent at the stereogenic C centre are trans with respect to one another. Intermolecular C—H⋯O hydrogen bonds are observed in the crystal lattice of (IIa) and (IIb).     

Ritter reactions. X. Structure of a new multicyclic amide-benzene inclusion compound

5H-Dibenzo[a, d]cyclohepten-5-ol1 can undergo Ritter reaction with acetonitrile and sulfuric acid to afford either the acetamide derivative2 or the multicyclic amide3 depending on the conditions used. The X-ray structure of the inclusion compound of3 with benzene is reported here and analysed in structural terms. This material [(C₁₉H₁₈N₂O)–(C₆H₆),Cc,a=10.694(5),b=22.843(5),c=9.901(4) Å,=124.02(2)°,Z=4,R=0.054] has molecules of3 linked by –N–HO=C intermolecular hydrogen bonds to form parallel chains alongc. Additional inter-host stabilisation is achieved by face-face interactions involving one of the two benzo rings of3. A hydrogen atom of the other host benzo group participates in an edge-face interaction with the benzene guest molecule to produce the inclusion compound. Benzenebenzene inter-guest interactions provide a further, but minor, contribution to the net stability of the structure. Supplementary Data relating to this article are deposited with the British Library as supplementary publication No. SUP 82189 (10 pages).     

Crystal structures of bis(quinidinium) molybdate hydrate and quinidinium chloride hydrate: The question of the stable conformation of quinidine

Anx-ray structural study of [QndH⁺]₂[MoO ₄ ^2– ]H₂O (1) and [QndH⁺]Cl^–H₂O (2), where Qnd = quinidine, was conducted. The structures have an ionic structure, and the ions are joined by hydrogen bonds into chains (1) and layers (2). Quinidinium cations protonated at the quinuclidine N atom have a conformation with agauche position of the N atom and OH group (as in neutral quinidine) corresponding to the local, and not the global, minimum of the calculated conformational energy.A. N. Nesmeyanov Institute of Organoelemental Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 1073–1078, May, 1992.     

Preparation and steric structure of 3(2H)-pyridazinones and 1,2-oxazin-6-ones fused with three- to six-membered saturated carbocycles or norbornane skeleton

Summary Reactions ofcis-2-(4-methylbenzoyl)-cyclopropane- (1) and-cyclobutanecarboxylic acids (2), the stereoisomeric cyclohexyl homologues (3 and4), and di-endo-3-(4-methylbenzoyl)-bi-cyclo-[2.2.1]heptane-2-carboxylic acid (5) with hydrazines yield the cycloalkane-condensed (3(2H)-pyridazinones6–9 and the norbornane di-endo-fused derivatives10. With hydroxylamine, compounds1 and3–5 were transformed to the cycloalkane- and norbornane-condensed 1,2-oxazin-6-ones11–14. Transformation of3–5 led to thetrans-hexahydroanthrone17a and its methylene-bridged analogue24. From the stereoisomeric hexahydro-1(3H)-isobenzofuranones20 and21, the partly saturated anthrones were also prepared; the products (16b and17b) contain the methyl substituent in position 6. On reduction,16b yield the 2-methyloctahydroanthracene22. The structures of the compounds were proved by¹H and¹³C NMR spectroscopy, making use of NOE, DEPT, and CH-COSY techniques.

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Synthese und räumliche Struktur von mit drei- bis sechsgliedrigen gesättigten Homocyclen oder Norbornan kondensierten 3(2H)-Pyridazinonen und 1,2-Oxazin-6-onen

Zusammenfassung Die Reaktion voncis-2-(4-methylbenzoyl)-cyclopropan-(1) und-cyclobutancarbonsäuren (2), der stereoisomeren cyclohexyl-Homologen (3 und4) und von di-endo-3-(4-methylbenzoyl)-bicyclo[2.2.1]heptan-2-carbonsäure (5) mit Hydrazinen ergibt die cycloalkankondensierten 3(2H)-Pyridazinone6–9 und das methylenüberbrückte di-endo-Derivat10. Die Verbindungen1 und3–5 wurden mit Hydroxylamin zu den cycloalkan- und norbornankondensierten 1,2-Oxazin-6-onen11–14 umgesetzt.3–6 reagierten zumtrans-Hexahydroanthron17a und seinem methylenüberbrückten Analogen24. Die teilweise gesättigten Anthrone wurden auch aus den stereoisomeren Hexahydro-1(3H)-isobenzofuranonen20 und21 hergestellt (16b und17b), wobei der Methylsubstituent jedoch in Position 6 lokalisiert ist. Reduktion von16b ergab das 2-Methyloctahydroanthracen22. Die Strukturen der Verbindungen wurden durch NMR-Spektroskopie abgesichert (¹H,¹³C, DEPT, CH-COSY, NOE).

     

Hydrogen-bonded urea-anion host lattices. Part 2. Crystal structures of inclusion compounds of urea with tetraalkylammonium bicarbonates

New inclusion complexes (C₂H₅)₄N⁺HCO ₃ ^– ·(NH₂)₂CO·2H₂O (1) and (n-C₄H₉)₄N⁺HCO ₃ ^– ·3(NH₂)₂CO (2) have been prepared and characterized by X-ray crystallography. Crystal data, MoK radiation:1, space groupP2₁/n,Z=8,a=9.356(1),b=29.156(4),c=12.161(1) Å, =90.03(1)°,R _F =0.062 for 2214 observed data;2, space groupP,Z=2,a=8.404(2),b=12.352(2),c=14.377(4) Å,a=88.20(2), =89.56(2), =71.68(1)°,R _F =0.052 for 3092 observed data. In both compounds the tetraalkylammonium ions are sandwiched between puckered layers, which are constructed from [((NH₂)₂CO)₂(HCO ₃ ^– )₂], ribbons, each composed of centrosymmetric hydrogen-bonded urea dimers and bicarbonate dimers, by lateral linkage through water molecules in1, and by direct cross-linkage of an alternate, parallel arrangement of the urea/bicarbonate and complementary urea ribbons in2. Supplementary Data relating to this article have been deposited with the British Library as Supplementary Publication No. SUP 82201 (40 pages).     

Kinetics and mechanism of the chromium(III)–picolinato chelate ring opening in some chromium(III)–oxalato–picolinato complexes in acidic aqueous solutions

Two Cr^III–picolinato complexes were obtained and characterized in solution. The [Cr(C₂O₄)(pyac)₂]^– and [Cr(C₂O₄)₂(pyac)]^2– ions (pyac = picolinic acid anion) in acidic solutions undergo a reversible one-end Cr^III–picolinato chelate ring opening via Cr^III—N bond breaking. The reaction rate was determined spectrophotometrically in the 0.1–1.0 M HClO₄ range at I = 1.0 M. The observed pseudo-first order rate constant depends on [H⁺] according to the equation: k _obs = a + b[H⁺] + c/[H⁺]. A reaction mechanism, which assumes participation of the protonated and unprotonated forms of the reactants, has been proposed. The kinetic parameters a, b, c have been defined as a = k ₁, b = k ₂ Q ₁, c = k _–1/Q ₂, where k ₁, k _–1,k ₂ are rate constants for the forward and reverse processes and Q ₁, Q ₂ are the protolytic equilibrium constants in the term of the proposed mechanism. The activation parameters have been determined and discussed.     

Conformational analysis of N-isopropylbenzohydroxamic acids: crystal structure, DFT, and NMR studies

X-ray crystal structure determinations together with density functional theory (DFT) calculations in vacuo and NMR studies in solution have been carried out for 4-MeOC₆H₄CONPrⁱOH 2a and 3,5-(NO₂)₂C₆H₃CONPrⁱOH 2b. The results were compared with that for the respective N-methyl benzohydroxamic acids. For crystal structures as well as for DFT-optimized geometries of 2 (both isomers) in vacuo, the effect of substituents in aromatic ring manifested by changing of charges is inconspicuous. Studies of potential energy surfaces showed that libration barrier around ω ₁ = 0° is low enough to make electron conjugation feasible, and that for 2b rotation barrier around C(O)N bond is higher by 6 kcal/mol and additionally, that rotation around N–C bond is hindered. A careful analysis of low-temperature ¹H NMR spectra confirmed the greater stability of Z-2a, the greater rigidity of E-2b and the influence of solvent on both isomers population. Despite solvent-dependent conformational alteration, both 2a and 2b crystallize exclusively as E isomers from ethyl acetate solution. Correlations of absolute ¹H, ¹³C, and ¹⁵N shielding calculations with experimental data were also analyzed. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Über die Bleitetraacetatoxydation von Methoxyphenolen

Zusammenfassung Die Untersuchung der Reaktionsweise der zwei Methoxy-o-chinolacetate Ia und IIa ergab, daß Ia bei der Dienon-Phenol-Umlagerung und bei der alkalischen Spaltung des Acetylendicarbonsäureester-Adduktes nicht die erwarteten Produkte lieferte. Die Konstitution des bei der letztgenannten Reaktion erhaltenen Stoffes If haben wir bewiesen, bei dem durch die Dienon—Phenol-Umlagerung erhaltenen Diphenylderivat ist das noch nicht der Fall. Bei IIa verlaufen diese beiden Reaktionen normal (zu IIb und IIc). Ebenfalls normal geht die Addition von CN^–, C₆H₅SH und C₆H₅SO₂H an Ia vor sich (zu Ib–Id).Mit 2 AbbildungenHerrn Prof. Dr.E. Hayek zum 60. Geburtstag.Zugleich 10. Mitt. über die Bleitetraacetatoxydation von Phenolen.     

Diastereoselective formation of calcium and ytterbium ansa-metallocenes via recombination of guaiazulene (Gaz) radical anions. Molecular structure of ansa-(η5-Gaz)2Ca(THF)2 and ansa-(η5-Gaz)2Yb(Py)2 (Gaz = 1,4-dimethyl-7-isopropylazulene) complexes

ansa-Metallocene derivative (⁵-Gaz)₂Ca(THF)₂ (1) (Gaz = 1,4-dimethyl-7-isopropylazulene) was synthesized by the reaction of CaI₂(THF)₂ with two equivalents of potassium and two equivalents of guaiazulene in THF. The ytterbium analog ansa-(⁵-Gaz)₂Yb(THF)₂ (2a) was synthesized by the reduction of guaiazulene with ytterbium naphthalenide in THF. The recrystallization of 2a from pyridine leads to the exchange of the coordinated solvent molecules and gives ansa-(⁵-Gaz)₂Yb(NC₅H₅)₂ (2b). The molecular structures of 1, 2a, and 2b were determined by X-ray diffraction analysis. The crystals of 1, 2a, and 2c consist of a racemic mixture of both R,R- and S,S-enantiomers. The calcium and ytterbium atoms ⁵-coordinate the five-membered rings of the guaiazulene ligands. The ¹H NMR spectroscopic and X-ray diffraction data unambiguously confirm the exclusive formation of N₂-symmetric ansa-metallocenes in these reactions. The reaction of compound 1 with Me₃SiCl in THF occurs with retention of the N—N bond between two guaiazulene moieties and affords bis(1,4-dimethyl-3-trimethylsilyl-7-isopropylazulene) (3) in high yield.     

Crystal structure of tetraethylammonium fluoride-water (4/11), 4(C2H5)4N+F− · 11H2O,a clathrate hydrate containing linear chains of edge-sharing (H2O)4F− tetrahedra and bridging water molecules

Crystals of 4(C₂H₅)₄N⁺F^– · 11H₂O are orthorhombic, space groupPna2₁, witha=16.130(3),b=16.949(7),c=17.493(7) Å, andZ=4. The structure was shown to be a clathrate hydrate containing infinite chains of edge-sharing (H₂O)₄F^– tetrahedra extending parallel to thea axis. The chains are laterally linked by bridging water molecules to form a three-dimensional hydrogen-bonded anion/water framework. The ordered (C₂H₅)₄N⁺ cations occupy the voids in two open channel systems running in theb andc directions. FinalR _F =0.091 for 2278 observed MoK data measured at 22°C. Supplementary Data: relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82010 (20 pages).Dedicated to Professor H. M. Powell.     

Peri Interactions in Naphthalene Diketones: A Preference for (Z,Z) Conformations

The crystal structures of 1,8-dibenzoylnaphthalene (9), 1,4,5,8-tetrabenzoylnaphthalene (10), and 1,8-diacetylnaphthalene (11) have been determined by X-ray diffraction. Diketone 9 crystallizes in triclinic space group P ^—1 with a = 7.924(2), b = 14.068(3), c = 7.876(1) Å, = 99.47(2), = 90.58(1), = 91.43(2)°. Tetraketone 10 crystallizes in monoclinic space group P2₁/c a = 7.374(4), b = 11.960(5), c = 15.524(5) Å, = 93.15(5)°. Diketone 11 crystallizes in orthorhombic space group Pbca a = 6.986(3), b = 15.946(4), c = 8.257(1) Å. Each of these naphthalene ketones adopt a (Z,Z) conformation, with torsion angles O—C—C¹—C^8a/O—C—C⁸—C^8a of 49.8°/44.5° (9), 52.1°/46.6° (10), and 44.8°/42.4° (11). The structures 9–11 are overcrowded with the distances between two neighboring carbonyl carbon atoms being significantly shorter than the sum of the van der Waals radii of two carbon atoms (342 pm): 293.4 pm (9), 281.6 pm (10), and 293.0 pm (11).     

Chemical bond inside a fullerene cage: is it possible?

The geometries, electronic structures, and hyperfine coupling constants of azafullerene C₅₉N (a π-electron radical) and its derivatives, C₅₉NH and endofullerene H@C₅₉N, were calculated at the B3LYP level of the density functional theory. Analysis of calculated potential energy profiles along trajectories of the motion of encapsulated hydrogen atom from the center of the fullerene sphere toward different atoms of C₅₉N revealed formation of a chemical bond between the H atom and a carbon atom that is involved in the 6,6-bond with the N atom and bears the most part of the π-electron spin density. The C—H endo-bond length is 1.12 Å, the bond dissociation energy being equal to 26.4 kcal mol⁻¹. The C—H exo-bond involving the same carbon atom is 0.02 Å shorter than the endo-bond, the bond dissociation energy being much higher (78.4 kcal mol⁻¹).__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 51–54, January, 2005.