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ABSTRACT: A painless way to tighten your belt: Structural characterization of the multiply charged fragment of an armchair nanotube that was formed by reduction of the neutral molecule with potassium metal revealed a remarkable elliptical distortion of the carbon core. The resulting tetraanions underwent supramolecular aggregation with potassium cations, and solvated guests were encapsulated inside the negatively charged polyarene cavity.
Angewandte Chemie International Edition 04/2013; · 13.45 Impact Factor
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ABSTRACT: Stack it up: Reduction of corannulene with an excess of lithium metal in dimethoxyethane (DME) results in the formation of remarkable multilayered supramolecular aggregates having lithium alkoxo nanobelts encapsulated between two tetrareduced corannulene bowls, [C(20) H(10) (4-) /Li(6) (OR)(6) Li(6) /C(20) H(10) (4-) ](2-) . The alkoxo groups (R=CH(3) O or/and CH(3) OCH(2) CH(2) O) are products of the Li-induced DME cleavage.
Angewandte Chemie International Edition 10/2012; · 13.45 Impact Factor
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ABSTRACT: Single-crystal X-ray diffraction studies of two polyaromatic radical anions crystallized as sodium salts, namely [Na(DME)(3) ](+) [C(20) H(10) (-) ] (1) and [Na(DME)(3) ](+) [C(24) H(12) (-) ] (2) are reported. This allowed the first structural evaluation of Jahn-Teller (JT) effects for monoreduced circulenes and a comparison between bowl-shaped corannulene and planar coronene. The C(s) and D(2h) symmetrical distortions are found to fit the experimental data for C(20) H(10) (.) (-) and C(24) H(12) (.) (-) , respectively. The continuous symmetry measure (CSM) analysis was carried out to provide a quantitative measure of the JT distortions in 1 and 2. In addition, the X-ray crystallographic results were fully supported by DFT calculations.
Chemistry 10/2012; · 5.93 Impact Factor
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ABSTRACT: The first comprehensive theoretical investigation of a series of functionalized fullerene cations, {R-C(60)}(+), where R = H, CH(3), CH(2)Cl, CHCl(2), and CCl(3), is accomplished. A detailed consideration of conformational energetic profiles of these systems resulted in the structures of most stable conformers that fit all available experimental data. The trends in stability of {R-C(60)}(+) cations as well as transition barriers for migration of alkyl groups over the C(60)-surface are provided. A thorough study of energetics of {R-C(60)}(+) is augmented by in-depth investigation of their electronic structures and aromaticity. As the final part of this study, the detailed comparison of structures, energetics and properties of {R-C(60)}(+) with those of corannulene cations, {R-hub-C(20)H(10)}(+), is performed at the same level of theory. The similarities and differences between the surface functionalized ball- and bowl-shaped carbocations are illuminated.
Physical Chemistry Chemical Physics 07/2012; 14(31):10935-43. · 3.57 Impact Factor
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ABSTRACT: The tetranuclear mixed-valent oxo-cluster [SnIISnIVO(O2CCF3)4]2 (1) has been prepared by reacting SnCl2 with AgO2CCF3 in a sealed ampoule at 90°C. Alternatively, 1 was obtained by acidolysis of Ph3SnSnPh3 with trifluoroacetic acid in solution. The X-ray diffraction study of 1 revealed the presence of a SnIIOSn2IVOSnII core comprised of the penta-coordinated divalent and six-coordinated tetravalent tin atoms. The 119Sn NMR studies confirmed the stability of the cluster in solution and the presence of two different oxidation states of tin.
An acidolysis of Ph3SnSnPh3 in the presence of [Cu2II(O2CCF3)4] followed by sublimation of the resulting product at 90°C afforded the first trinuclear mixed metal Sn–Cu cluster [(C6H5)2Sn2IVCuIIO(O2CCF3)6] (2). The X-ray diffraction analysis of 2 revealed the presence of two phenyl groups attached to the six-coordinated tin(IV) atoms and the tetragonal pyramidal environment
of the copper(II) atom. Both complexes have been obtained free of exogenous ligands.
KeywordsTrifluoroacetate-Tin-Copper-Molecular structure-X-ray diffraction
Journal of Cluster Science 04/2012; 21(3):361-370. · 0.92 Impact Factor
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ABSTRACT: Bowl-shaped mono- and dianions are prepared by reduction of corannulene (C(20)H(10), 1) with sodium and potassium metals in the presence of [18]crown-6 ether. Single-crystal X-ray diffraction studies of two sodium salts, [Na(THF)(2)([18]crown-6)](+)[1(-)] (2a) and [Na([18]crown-6)](+)[1(-)] (2b), reveal the presence of naked corannulene monoanions 1(-) in both cases. In contrast, the potassium adduct, [K([18]crown-6)](+)[1(-)] (3), shows an η(2)-binding of the K(+) ion to the convex face of 1(-). For the first time, corannulene dianions have been isolated as salts with sodium, [Na(2)([18]crown-6)](2+)[1(2-)] (4a) and [Na(THF)(2)([18]crown-6)](+)[Na([18]crown-6)](+)[1(2-)] (4b), and potassium counterions, [K([18]crown-6)](2)(+)[1(2-)] (5). Their structural characterization reveals geometry perturbations upon addition of two electrons to a bowl-shaped polyarene. It also demonstrates η(5)- or η(6)-binding of metals to the curved carbon surface of 1(2-), depending on the crystallization conditions. Both mono- and doubly-charged corannulene bowls show the preferential exo binding of Na(+) and K(+) ions in all investigated compounds. Various types of C-H···π interactions are found in the crystals of 2-5. The UV/Vis, ESR, and (1)H NMR spectroscopic studies of 2-5 indicate different coordination environment of corannulene anions in solution, depending on the metal ion.
Chemistry 04/2012; 18(21):6476-84. · 5.93 Impact Factor
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ABSTRACT: Lots of potential: a trifluoromethylated corannulene, C(5)-C(20)H(5)(CF(3))(5), has been prepared and characterized spectroscopically and by X-ray crystallography. The structure exhibits a highly ordered bowl stacking that is unusual for corannulenes with acyclic substituents. The first reduction of C(5)-C(20)H(5)(CF(3))(5) is anodically shifted by 0.95 V, making it the strongest corannulene-based electron acceptor to date.
Angewandte Chemie International Edition 04/2012; 51(20):4939-42. · 13.45 Impact Factor
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ABSTRACT: A new dirhodium(II,II) paddlewheel complex, [Rh(2)(O(2)CC(6)H(4)COOC(2)H(5))(4)] (1), has been synthesized using a predesigned functionalized carboxylate, namely, 4-(ethoxycarbonyl)benzoate. The target product has been crystallized from the acetone solution and structurally characterized as a bis-acetone adduct, [Rh(2)(O(2)CC(6)H(4)COOC(2)H(5))(4)(OCMe(2))(2)]·C(6)H(14) (2). By utilizing the ability of dangling ester groups to coordinate to open axial ends of neighboring dirhodium units, 1 can self-assemble to form 2D networks upon crystallization from solutions of noncoordinating solvents such as chlorobenzene and chloroform. The resulting [Rh(2)(O(2)CC(6)H(4)COOC(2)H(5))(4)]·2C(6)H(5)Cl (3) and [Rh(2)(O(2)CC(6)H(4)COOC(2)H(5))(4)]·2CHCl(3) (4) products have microporous solid state structures with the pores filled with the corresponding disordered solvent molecules. Notably, 3 and 4 represent unique examples of 2D extended frameworks based on dirhodium tetracarboxylate paddlewheel units devoid of any exogenous ligands. In solution, the dangling ends of carboxylate bridges of 1 have been successfully utilized for condensation reaction with the selected solid support, benzylamine-functionalized polystyrene, allowing successful heterogenization of dirhodium units through the equatorial covalent attachment to the substrate. The resulting solid product was tested as a catalyst in the cyclopropanation reaction of styrene with methyl phenyldiazoacetate to show good yields and diastereoselectivity.
Inorganic Chemistry 04/2012; 51(8):4855-61. · 4.60 Impact Factor
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ABSTRACT: The first theoretical investigation of a series of surface-decorated corannulene cations, {R-C(20)H(10)}(+), where R = H, CH(3), CH(2)Cl, CHCl(2), and CCl(3), is accomplished. Three possible isomers of {R-C(20)H(10)}(+) such as hub-, rim-, and spoke-functionalized corannulene derivatives are considered and compared. The trends in their stability and transition barriers are provided. A detailed study of energetics of {R-C(20)H(10)}(+) is complemented by in-depth investigation of their electronic structures and aromaticity.
Physical Chemistry Chemical Physics 02/2012; 14(10):3554-67. · 3.57 Impact Factor
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ABSTRACT: The reaction of corannulene (C(20)H(10)) with 1,2-C(2)H(4)Hal(2) (Hal = Cl or Br) in the presence of AlCl(3) affords stable nonplanar carbocations C(20)H(10)CH(2)CH(2)Hal(+) (Hal = Cl (1) and Br (2)) with an -CH(2)CH(2)Hal moiety attached to the interior carbon atom of the bowl. In the analogous reaction with 1-bromo-2-chloroethane, the selective (up to 98%) abstraction of chloride is observed with the formation of cation 2. The molecular structures of bowl-shaped carbocations 1 and 2 crystallized as salts with AlCl(4)(-) counterions are revealed by single-crystal X-ray diffraction. The reaction of 2 with methanol or ethanol provides further decoration of the nonplanar polyarene upon the nucleophilic addition of alkoxy groups to the exterior carbon atom of the corannulene moiety. The (1)H NMR investigation of the corresponding products, C(20)H(10)(CH(2)CH(2)Br)(OCH(2)R) (R = H (3) and CH(3) (4)), shows the formation of intramolecular H···O and H···Br hydrogen bonds.
The Journal of Organic Chemistry 12/2011; 76(23):9572-6. · 4.45 Impact Factor
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ABSTRACT: The first successful high-yield solution synthesis of homobimetallic Bi(2)(O(2)CCF(3))(4) (1), as well as heterobimetallic BiRh(O(2)CCF(3))(4) (2) and BiRh(O(2)CCF(2)CF(3))(4) (3), complexes is reported. It is based on one-pot reduction reactions starting from Bi(III) and Rh(II) carboxylates and using Bi metal as a reducing agent. The presence of small amounts of diphenyl ether was found to facilitate this reaction, most probably because of its good solubilizing and π-stabilizing abilities. The latter is illustrated by the isolation and structural characterization of a π-adduct of 1 with diphenyl ether, [Bi(2)(O(2)CCF(3))(4)·1/2Ph(2)O]. Importantly, the new approach expands to solution the chemistry of Bi(II) that was previously limited to the solid state only. The solution procedure developed for the preparation of heterometallic BiRh(O(2)CCF(3))(4) is now one step shorter and gives the product in excellent yield compared with the previously reported method based on sublimation-deposition technique. It is also performed on a greater scale (~10-20 times) and makes further scale-up feasible, if needed. Moreover, it eliminates the isolation of the hard-to-handle unsolvated Bi(II) trifluoroacetate used earlier as a starting material. A new polymorph of BiRh(O(2)CCF(3))(4) (2) was crystallized from solution in this work. The solution approach was also applied to the synthesis of a new heterobimetallic carboxylate with perfluorinated propionate ligands, BiRh(O(2)CCF(2)CF(3))(4) (3). All products are fully characterized by spectroscopic and single crystal X-ray diffraction methods. Complexes 2 and 3 exhibit similar solid state structures based on heterobimetallic paddlewheel units forming infinite 1D chains through intermolecular Rh···O interactions.
Inorganic Chemistry 12/2011; 51(1):566-71. · 4.60 Impact Factor
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10/2011: pages 157 - 185; , ISBN: 9781118011263
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ABSTRACT: X-Ray diffraction studies of three aliphatic copper(I) carboxylates revealed a tetranuclear core structure for [Cu(4)(O(2)CCH(2)CH(3))(4)] (1), [Cu(4)(O(2)CCF(3))(O(2)CCH(2)CH(3))(3)] (2), and [Cu(4)(O(2)CCF(2)CF(3))(4)] (3). The effect of a stepwise increase in electrophilicity on solid-state interactions of copper(I) tetramers as well as the implications of structural variations on photoluminescent properties of the above copper(I) propionates have been discussed.
Dalton Transactions 09/2011; 40(34):8598-603. · 3.84 Impact Factor
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ABSTRACT: Lithium-coordinated polyaromatic anions such as tetrareduced corannulene, C(20)H(10)(4-) (1(4-)), are useful substrates to model and ultimately improve the graphitic electrodes in lithium-ion (Li(+)) batteries. Previous studies suggested that 1(4-) forms dimers encasing four Li(+) ions in solution. Here, we report a single-crystal x-ray diffraction analysis confirming the formation of a sandwich-type supramolecular aggregate with a high degree of alkali metal intercalation. In contrast to the prior model, our data reveal that five Li(+) ions are sandwiched between the two tetrareduced corannulene decks, and (7)Li nuclear magnetic resonance spectroscopy delineates a conserved structure in tetrahydrofuran solution. Remarkably, the sandwich is robust in both solution and solid states even in the presence of crown ethers that compete for Li(+) coordination. These results should help elucidate Li(+) intercalation motifs between curved carbon surfaces more broadly.
Science 08/2011; 333(6045):1008-11. · 31.20 Impact Factor
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ABSTRACT: The ion size matters: The structures of corannulene monoanions crystallized with Cs(+) and Rb(+) ions in the presence of [18]crown-6 reveal the intrinsic binding preferences of alkali metals and allow evaluation of the bowl deformation caused by negative charge distribution and metal binding. The large cesium cation coordinates exclusively to the concave face of C(20) H(10) (-) , whereas the smaller rubidium cation exhibits convex binding.
Angewandte Chemie International Edition 07/2011; 50(35):8090-4. · 13.45 Impact Factor
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ABSTRACT: An unprecedented "molecular wire" type of structure for the copper(I) carboxylate family has been synthesized by utilizing copper-copper interactions and controllable switch of copper-oxygen interactions. Several modifications of the same complex, copper(I) 2,4,6-triisopropylbenzoate, have been isolated to allow evaluation of the structural variation effects on photoluminescent behavior.
Chemical Communications 06/2011; 47(24):6939-41. · 6.17 Impact Factor
