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James L. Dye - One of the best experts on this subject based on the ideXlab platform.

  • One-dimensional zigzag chains of Cs-: the structures and properties of Li+ (Cryptand[2.1.1])Cs- and Cs+ (Cryptand[2.2.2])Cs-.
    The journal of physical chemistry. B, 2006
    Co-Authors: Andrew S. Ichimura, Rui H Huang, Qingshan Xie, Philip Morganelli, And Amy Burns, James L. Dye
    Abstract:

    The crystal structure and properties of lithium (Cryptand[2.1.1]) ceside, Li+ (C211)Cs-, are reported. Li+ (C211)Cs- is the second ceside and third alkalide with a one-dimensional (1D) zigzag chain of alkali metal anions. The distance between adjacent Cs- anions, 6 A, is shorter than the sum of the van der Waals radii, 7 A. Optical, magic angle spinning NMR, two-probe alternating and direct current conductivity, and electron paramagnetic resonance measurements reveal unique physical properties that result from the overlap of adjacent Cs- wave functions in the chain structure. The properties of cesium (Cryptand[2.2.2]) ceside, Cs+ (C222)Cs-, were also studied to compare the effects of the subtle geometric changes between the two 1D zigzag chain structures. Li+ (C211)Cs- and Cs+ (C222)Cs- are both low-band-gap semiconductors with anisotropic reflectivities and large paramagnetic 133Cs NMR chemical shifts relative to Cs- (g). An electronic structure model consistent with the experimental data has sp2-hybridized Cs- within the chain and sp-hybridized chain ends. Ab initio multiconfiguration self-consistent field calculations on the ceside trimer, Cs3(3-), support this model and indicate a net bonding interaction between nearest neighbors. The buildup of electron density between adjacent Cs- anions is visualized through an electron density difference map constructed by subtracting the density of three cesium atoms from the short Cs3(3-) fragment.

  • One-Pot Synthesis of 1,4,7,10,13,16,21,24-Octaazabicyclo[8.8.8]hexacosane - The Peraza Analogue of [2.2.2]Cryptand
    Synthesis, 2006
    Co-Authors: Mikhail Y. Redko, James L. Dye, Rui Huang, James E. Jackson
    Abstract:

    The peraza analogue of polyether Cryptand [2.2.2], 1,4,7,10,13,16,21,24-octaazabicyclo[8.8.8]hexacosane, has been synthesized in 70% yield via a two-step one-pot procedure by the condensation of tris(2-aminoethyl)amine (tren) with glyoxal in isopropanol at -78 °C followed by reduction of the intermediate with Na/liquid NH 3 . This preparation is significantly faster, simpler, and higher yielding than the previously reported two-step procedure, with its lengthy isolation process and 45% overall yield.

  • Anisotropic Charge Transport and Spin−Spin Interactions in K+(Cryptand [2.2.2]) Electride
    The Journal of Physical Chemistry B, 2002
    Co-Authors: Andrew S. Ichimura, And Michael J. Wagner, James L. Dye
    Abstract:

    Single-crystal conductivity measurements of the electride K+(Cryptand[2.2.2])e- show pronounced anisotropy. Conductivity of the sheetlike crystals is 10−30 times greater in the “easy” than in the “hard” in-plane direction and 105−106 times greater than that perpendicular to the plane. The magnetic susceptibility is well-described by the alternating linear chain Heisenberg antiferromagnetic model. Both phenomena are consistent with the structure, which has very open pseudo-1D channels that connect large dumbbell-shaped two-electron cavities to form a chain of coupled electron spins. Slightly smaller channels interconnect these chains to form a 2D network of channels and cavities. The proposed conductivity mechanism is the random 2D hopping of hole defects that are highly mobile down the open 1D chain. They undergo activated transport to adjacent chains as a result of defect sites (such as K-) in the primary chain.

  • structure and properties of a new electride rb Cryptand 2.2.2 e
    Journal of the American Chemical Society, 2000
    Co-Authors: Qingshan Xie, Richard C. Phillips, And William P. Pratt, Rui H Huang, Andrew S. Ichimura, James L. Dye
    Abstract:

    This is the sixth electride whose crystal structure has been determined and the fourth to show polymorphism. Crystals of the title electride prepared from mixed solvents have a structure similar to that of Li+(Cryptand[2.1.1])e-. Electrons occupy cavities that are connected by “ladder-like” channels. The static and spin magnetic susceptibilities of polycrystalline samples that contain this polymorph (called phase α) show Heisenberg 1D antiferromagnetic behavior with −J/kB = 30 K. Similar to other electrides with “localized” electrons, this electride is a poor conductor (σ < 10- 4 ohm-1cm-1). Thin films prepared by high vacuum co-deposition of Rb metal and Cryptand[2.2.2] have optical spectra and near-metallic electrical conductivity nearly identical with those of K+(Cryptand[2.2.2])e-. These properties would not be expected if the film structure were the same as that obtained for crystals. Rather, they suggest that the films consist of microcrystals whose structure is similar to that of K+(Cryptand[2.2.2]...

  • Thermionic Emission from Cold Electride Films
    Chemistry of Materials, 2000
    Co-Authors: Richard C. Phillips, And William P. Prattjr., James L. Dye
    Abstract:

    Thermionic electron emission from 2000−4000 A thick films of K+(Cryptand[2.2.2])e- and Rb+(Cryptand[2.2.2])e- was studied as a function of temperature and time. The total charge collected was generally several hundred nanocoulombs with peak currents in the range of 5−100 pA. Although electron emission was not a direct result of thermal decomposition of the films, the peak current correlated with the decomposition rate. At a given temperature, the current increased gradually to a peak value and then decreased to near zero. Interrupting the process by cooling before complete decay, followed by a return to the same temperature, restored the previous current−time behavior. Once the current had decayed to near zero, the only way to restore emission was to raise the temperature above the previous value. The process of growth and decay was then repeated. The origin of emission is unknown, but the behavior suggests the presence of surface defect sites at grain boundaries that are initially empty. Sample decomposi...

Kim M. Baines - One of the best experts on this subject based on the ideXlab platform.

  • Chemical state determination of molecular gallium compounds using XPS
    Dalton transactions (Cambridge England : 2003), 2016
    Co-Authors: Jeremy L. Bourque, Mark C. Biesinger, Kim M. Baines
    Abstract:

    A series of molecular gallium compounds were analyzed using X-ray photoelectron spectroscopy (XPS). Specifically, the Ga 2p3/2 and Ga 3d5/2 photoelectron binding energies and the Ga L3M45M45 Auger electron kinetic energies of compounds with gallium in a range of assigned oxidation numbers and with different stabilizing ligands were measured. Auger parameters were calculated and used to generate multiple chemical speciation (or Wagner) plots that were subsequently used to characterize the novel gallium-Cryptand[2.2.2] complexes that possess ambiguous oxidation numbers for gallium. The results presented demonstrate the ability of widely accessible XPS instruments to experimentally determine the chemical state of gallium centers and, as a consequence, provide deeper insights into reactivity compared to assigned oxidation and valence numbers.

  • synthesis and characterization of cationic low valent gallium complexes of Cryptand 2.2.2
    Chemistry: A European Journal, 2015
    Co-Authors: Jeremy L. Bourque, Paul D. Boyle, Kim M. Baines
    Abstract:

    The synthesis and characterization of two bimetallic, cationic low-valent gallium-Cryptand[2.2.2] complexes is reported. The reaction of Cryptand[2.2.2] with Ga2Cl4 gave two different cations, [Ga3Cl4 (crypt-222)](+) (1) or [Ga2Cl2 (crypt-222)](2+) (2), depending on whether or not trimethylsilyl triflate (Me3SiOTf) was added as a co-reagent. Complexes 1 and 2 are the first examples of bimetallic Cryptand[2.2.2] complexes, as well as the first low-valent gallium-Cryptand[2.2.2] complexes. Computational methods were used to evaluate the bonding in the gallium cores.

  • Synthesis and Characterization of Cationic Low‐Valent Gallium Complexes of Cryptand[2.2.2]
    Chemistry (Weinheim an der Bergstrasse Germany), 2015
    Co-Authors: Jeremy L. Bourque, Paul D. Boyle, Kim M. Baines
    Abstract:

    The synthesis and characterization of two bimetallic, cationic low-valent gallium-Cryptand[2.2.2] complexes is reported. The reaction of Cryptand[2.2.2] with Ga2Cl4 gave two different cations, [Ga3Cl4 (crypt-222)](+) (1) or [Ga2Cl2 (crypt-222)](2+) (2), depending on whether or not trimethylsilyl triflate (Me3SiOTf) was added as a co-reagent. Complexes 1 and 2 are the first examples of bimetallic Cryptand[2.2.2] complexes, as well as the first low-valent gallium-Cryptand[2.2.2] complexes. Computational methods were used to evaluate the bonding in the gallium cores.

  • Cationic Cryptand complexes of tin(II).
    Inorganic chemistry, 2012
    Co-Authors: Jessica C. Avery, Paul A Rupar, Margaret A. Hanson, Rolfe H. Herber, Kamila J. Bladek, Israel Nowik, Yining Huang, Kim M. Baines
    Abstract:

    A series of cationic Cryptand complexes of tin(II), [Cryptand[2.2.2]SnX][SnX3] (10, X = Cl; 11, X = Br; 12, X = I) and [Cryptand[2.2.2]Sn][OTf]2 (13), were synthesized by the addition of Cryptand[2.2.2] to a solution of either tin(II) chloride, iodide, or trifluoromethanesulfonate. The complexes could also be synthesized by the addition of the appropriate trimethylsilyl halide (or pseudohalide) reagent to a solution of tin(II) chloride and Cryptand[2.2.2]. The complexes were characterized using a variety of techniques including NMR, Raman, and temperature-dependent Mossbauer spectroscopy, mass spectrometry, and X-ray diffraction.

  • Cationic Cryptand Complexes of Tin(II)
    2012
    Co-Authors: Jessica C. Avery, Paul A Rupar, Margaret A. Hanson, Rolfe H. Herber, Kamila J. Bladek, Israel Nowik, Yining Huang, Kim M. Baines
    Abstract:

    A series of cationic Cryptand complexes of tin­(II), [Cryptand[2.2.2]­SnX]­[SnX3] (10, X = Cl; 11, X = Br; 12, X = I) and [Cryptand[2.2.2]­Sn]­[OTf]2 (13), were synthesized by the addition of Cryptand[2.2.2] to a solution of either tin­(II) chloride, iodide, or trifluoromethanesulfonate. The complexes could also be synthesized by the addition of the appropriate trimethylsilyl halide (or pseudohalide) reagent to a solution of tin­(II) chloride and Cryptand[2.2.2]. The complexes were characterized using a variety of techniques including NMR, Raman, and temperature-dependent Mössbauer spectroscopy, mass spectrometry, and X-ray diffraction

V. A. Sharnin - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Water–Ethanol Solvents on the Protonation Constants of Cryptand[2.2.2]
    Russian Journal of Physical Chemistry A, 2018
    Co-Authors: V. A. Isaeva, V. A. Sharnin
    Abstract:

    The protonation constants of Cryptand[2.2.2] are determined potentiometrically at 298 K in water–ethanol solvents of variable composition. An increase in the concentration of a solution’s nonaqueous component reduces the equilibrium constants of the reactions of mono- and biprotonated Cryptand[2.2.2] formation. The contribution from the resolvation of reagents to the change in the Gibbs energy of the studied reactions is estimated. The reduction in the protonation constants of Cryptand[2.2.2] in water–ethanol solvents is mainly due to enhancement of the solvation of protons in water–ethanol mixtures.

  • Thermodynamics of molecular complexation of glycyl–glycyl–glycine with Cryptand [2.2.2] in water–dimethylsulfoxide solvent at 298.15 K
    Journal of Thermal Analysis and Calorimetry, 2016
    Co-Authors: T. R. Usacheva, Irina V. Terekhova, Roman S. Kumeev, L. Pham Thi, V. A. Sharnin
    Abstract:

    The influence of water–dimethylsulfoxide (H_2O–DMSO) solvent on the reaction of the molecular complex formation between Cryptand [2.2.2] (L) and glycyl–glycyl–glycine (3Gly) was studied at T  = 298.15 K. The thermodynamic parameters for the reaction (lg K ^0, Δ_r G ^0, Δ_r H ^0, T Δ_r S ^0) were obtained from calorimetric titration experiments carried out by means of the calorimetric system TAM III (TA Instruments, USA). The binding mode of 3Gly–L complexation in H_2O–DMSO solvent was determined by NMR spectroscopy, and the spectroscopic data were also used to calculate the [3GlyL] stability constants. A slight increase in complex stability and reaction exothermicity was observed at increasing DMSO content. The thermodynamic parameters for [3GlyL] are compared with thermodynamic parameters of complex formation of 18-crown-6 with amino acids and 3Gly in mixed solvents using the solvation-thermodynamic approach.

  • Thermodynamics of molecular complexation of glycyl–glycyl–glycine with Cryptand [2.2.2] in water–dimethylsulfoxide solvent at 298.15 K
    Journal of Thermal Analysis and Calorimetry, 2016
    Co-Authors: T. R. Usacheva, L. Pham Thi, Irina V. Terekhova, Roman S. Kumeev, V. A. Sharnin
    Abstract:

    The influence of water–dimethylsulfoxide (H2O–DMSO) solvent on the reaction of the molecular complex formation between Cryptand [2.2.2] (L) and glycyl–glycyl–glycine (3Gly) was studied at T = 298.15 K. The thermodynamic parameters for the reaction (lgK0, ΔrG0, ΔrH0, TΔrS0) were obtained from calorimetric titration experiments carried out by means of the calorimetric system TAM III (TA Instruments, USA). The binding mode of 3Gly–L complexation in H2O–DMSO solvent was determined by NMR spectroscopy, and the spectroscopic data were also used to calculate the [3GlyL] stability constants. A slight increase in complex stability and reaction exothermicity was observed at increasing DMSO content. The thermodynamic parameters for [3GlyL] are compared with thermodynamic parameters of complex formation of 18-crown-6 with amino acids and 3Gly in mixed solvents using the solvation-thermodynamic approach.

  • thermodynamics of molecular complexation of glycyl glycyl glycine with Cryptand 2.2.2 in water dimethylsulfoxide solvent at 298 15 k
    Journal of Thermal Analysis and Calorimetry, 2016
    Co-Authors: T. R. Usacheva, V. A. Sharnin, Irina V. Terekhova, Roman S. Kumeev, Pham L Thi
    Abstract:

    The influence of water–dimethylsulfoxide (H2O–DMSO) solvent on the reaction of the molecular complex formation between Cryptand [2.2.2] (L) and glycyl–glycyl–glycine (3Gly) was studied at T = 298.15 K. The thermodynamic parameters for the reaction (lgK0, ΔrG0, ΔrH0, TΔrS0) were obtained from calorimetric titration experiments carried out by means of the calorimetric system TAM III (TA Instruments, USA). The binding mode of 3Gly–L complexation in H2O–DMSO solvent was determined by NMR spectroscopy, and the spectroscopic data were also used to calculate the [3GlyL] stability constants. A slight increase in complex stability and reaction exothermicity was observed at increasing DMSO content. The thermodynamic parameters for [3GlyL] are compared with thermodynamic parameters of complex formation of 18-crown-6 with amino acids and 3Gly in mixed solvents using the solvation-thermodynamic approach.

Rimma N Lyubovskaya - One of the best experts on this subject based on the ideXlab platform.

  • Solid-State Properties of Hexaazatriphenylenehexacarbonitrile HAT(CN)6.- Radical Anions in Crystalline Salts Containing Cryptand(M+ ) and Crystal Violet Cations.
    Chemistry (Weinheim an der Bergstrasse Germany), 2020
    Co-Authors: Dmitri V Konarev, Salavat S Khasanov, Alexey V. Kuzmin, Akihiro Otsuka, Hideki Yamochi, Hiroshi Kitagawa, Maxim V. Mikhailenko, Rimma N Lyubovskaya
    Abstract:

    Crystalline {Cryptand[2.2.2](Na+ )}{HAT(CN)6.- }⋅0.5C6 H4 Cl2 (1), {Cryptand[2.2.2](K+ )}{HAT(CN)6.- } (2), (CV+ ){HAT(CN)6.- } (3), and (CV+ ){HAT(CN)6.- }⋅2C6 H4 Cl2 (4) salts (where CV+ is the crystal violet cation) containing hexaazatriphenylenehexacarbonitrile radical anions have been obtained. The solid-state molecular structure as well as the optical and magnetic properties of HAT(CN)6.- are studied. The formation of HAT(CN)6.- in 1-4 leads to the appearance of new bands in the visible range, at 694 and 740 nm. The HAT(CN)6.- radical anions have spin state S=1/2 and are packed in one-dimensional stacks containing the {HAT(CN)6.- }2 dimers alternated with weaker interacting pairs of HAT(CN)6.- in 1 and nearly isolated {HAT(CN)6.- }2 dimers in 2. The {HAT(CN)6.- }2 dimers are diamagnetic in 1 but they effectively mediate one-dimensional antiferromagnetic coupling of spins within the stacks with moderate exchange interaction of J/kB = -80 K. The behaviour of salt 2 is described by a singlet-triplet model for the {HAT(CN)6.- }2 dimers with an energy gap of 434(±7) K. Magnetic behaviour of both salts agree well with the data of extended Huckel calculations. Salts 3 and 4 contain isolated stacks of alternated HAT(CN)6.- and CV+ ions, and in this case, nearly paramagnetic behaviour is observed with Weiss temperatures of -1 and -7 K, respectively. Narrow Lorentzian EPR signals with g = 2.0033-2.0039 were found for the HAT(CN)6.- radical anions in 1 and 4 but in solution g-factor shifts to 1.9964. The electronic structure of HAT(CN)6.- is analysed based on X-ray diffraction data for 2, showing a Jahn-Teller distortion of the radical anion that reduces the symmetry from D3h to Cs and splits the initially degenerated LUMOs.

  • Decacyclene Radical Anions Showing Strong Low-energy Intramolecular Absorption and Magnetic Coupling of Spins in a Hexagonal Network.
    Chemistry an Asian journal, 2020
    Co-Authors: Dmitri V Konarev, Salavat S Khasanov, Akihiro Otsuka, Hideki Yamochi, Hiroshi Kitagawa, Aleksey V. Kuzmin, Alexander F. Shestakov, Rimma N Lyubovskaya
    Abstract:

    Two salts of the aromatic hydrocarbon decacyclene, {Cryptand[2.2.2](Cs+ )} (decacyclene.- ) (1) and {Bu3 MeP+ }(decacyclene.- ) (2), were obtained. In both salts, decacyclene.- radical anions formed channels occupied by cations. However, corrugated hexagonal decacyclene.- layers could be outlined in the crystal structure of 1 with several side-by-side C⋅⋅⋅C approaches. The decacyclene.- radical anions showed strong distortion in both salts, deviating from the C3 symmetry owing to the repulsion of closely arranged hydrogen atoms and the Jahn-Teller effect. Radical anions showed intense unusually low energy absorption in the IR-range, with maxima at 4800 and 6000 cm-1 . According to the carculations, these bands can originate from the SOMO-LUMO+1 and SOMO-LUMO+2 transitions, respectively. Radical anions exhibited a S=1/2 spin state, with an effective magnetic moment of 1.72 μB at 300 K. The decacyclene.- spin antiferromagnetically coupled with a Weiss temperature of -11 K. Spin ordering was not observed down to 1.9 K owing to spin frustration in the hexagonal decacyclene.- layers.

  • Double‐Decker Paramagnetic {(K)(H3Hhp)2}⋅2− Radical Dianions Comprising Two [30]Trithia‐2,3,5,10,12,13,15,20,22,23,25,30‐Dodecaazahexaphyrins and a Potassium Ion
    Chemistry an Asian journal, 2019
    Co-Authors: Dmitri V Konarev, Salavat S Khasanov, Rimma N Lyubovskaya, Akihiro Otsuka, Hideki Yamochi, Hiroshi Kitagawa, Mikhail K. Islyaikin, Evgenii N. Ivanov, Oskar I. Koifman, Yuriy A. Zhabanov
    Abstract:

    Reduction of free-base [30]trithia-2,3,5,10,12,13,15,20,22,23,25,30-dodecaazahexaphyrin (H3 Hhp) yields {Cryptand[2.2.2](K)}2 {(K)(H3 Hhp)2 }⋅4C6 H4 Cl2 (1) containing double-decker {(K)(H3 Hhp)2 }⋅2- radical dianions, whose structure was elucidated using X-ray diffraction. Potassium ion forms 12 short (K+ )⋅⋅⋅N(H3 Hhp) contacts with two H3 Hhp macrocycles in the 3.048-3.157 A range. Dianions have S=1/2 spin state manifesting an effective magnetic moment of 1.64 μB at 300 K and a narrow Lorentzian electron paramagnetic resonance signal. Quantum chemical calculations support the ionic nature of the (K+ )-N(H3 Hhp) interactions and the nearly equal distribution of the -1.5 charge over each macrocycle. H3 Hhp takes the role of an aza-crown ether in free-base reduced state and forms a new type of double-decker complex.

  • negatively charged singly bonded dimers of c1 c70 cf3 10 and bare c70 fullerene
    New Journal of Chemistry, 2019
    Co-Authors: Dmitri V Konarev, Victor A. Brotsman, Sergey I. Troyanov, Salavat S Khasanov, Alexey A Goryunkov, Ilya N Ioffe, Rimma N Lyubovskaya
    Abstract:

    Salts of fullerene derivative C1-C70(CF3)10 and bare fullerene C70 with cryptates of alkali metals as cations have been obtained: {Cryptand[2.2.2](K+)}2[C70(CF3)10−]2·Solvent (1), {Cryptand[2.2.2](K+)}2(C70−)2·Solvent (2) and {Cryptand[2.2.1](Na+)}2(C70−)2·3C6H4Cl2 (3) in the form of single crystals. Radical anions of both functionalized and bare fullerene C70 form diamagnetic and EPR silent singly-bonded [C70(CF3)10−]2 and (C70−)2 dimers stable at least up to room temperature (according to the EPR data). The length of the intercage C–C bonds and the center-to-center interfullerene distances are 1.570(7) and 10.516 A for the [C70(CF3)10−]2 dimer in 1 and 1.576(4)–1.587(4) A and 10.493–10.507 A for the (C70−)2 dimers in 2 and 3. Optical spectra of 1–3 manifest new bands in the NIR range characteristic of negatively charged fullerenes. These bands are blue shifted in the spectrum of 1 with [C70(CF3)10−]2 in comparison with the spectrum of underivatized C70˙−. It is shown that negatively charged fullerene dimers show new low-energy broad absorption bands in the NIR range most probably associated with charge transfer between fullerene anions within the dimers. According to DFT calculations, the singly-bonded [C70(CF3)10−]2 dimer demonstrates negative binding energy in the gas phase, but becomes bound by 54 kJ mol−1 when the solvent effects are taken into account via the D-PCM model. Charge asymmetry incurred by CF3 groups at the pole region of anionic C1-C70(CF3)10 promotes its dimerization in the condensed phase.

  • Molecular structures, and optical and magnetic properties of free-base tetrapyrazinoporphyrazine in various reduction states
    New Journal of Chemistry, 2019
    Co-Authors: Dmitri V Konarev, Salavat S Khasanov, Maxim A. Faraonov, Alexey V. Kuzmin, Nikita G. Osipov, Akihiro Otsuka, Hideki Yamochi, Hiroshi Kitagawa, Rimma N Lyubovskaya
    Abstract:

    Reduction of free-base tetrapyrazinoporphyrazine (H2TPyzPz) under different experimental conditions allowed us to obtain radical anion salt {Cryptand[2.2.2](K+)}2(H2TPyzPz˙−)2·3C6H4Cl2 (1), and dianion salts {Cryptand[2.2.2](K+)}2(H2TPyzPz2−)·C6H4Cl2 (2) and {Cryptand[2.2.2](K+)}2(H2TPyzPz2−)·[CpFe(CO)2]2·3C6H4Cl2 (3) in the form of single crystals. The molecular structure, and optical and magnetic properties of free-base tetrapyrazinoporphyrazine in various reduction states were studied for the first time. Reduction of the macrocycle is accompanied by the appearance of alternation of the C–Nmeso bonds, blue shift of both the Soret and Q-bands and the appearance of new bands in the NIR range. Salt 1 contained paramagnetic H2TPyzPz˙− radical anions half of which formed face-to-face type dimers with very effective π–π interaction, whereas the rest were magnetically isolated from the other H2TPyzPz˙− radical anions. Strong antiferromagnetic coupling of spins with a magnetic exchange interaction of J/kB = −140 K was observed in these dimers. In 2 and 3, diamagnetic dianions H2TPyzPz2− were completely isolated.

Dmitri V Konarev - One of the best experts on this subject based on the ideXlab platform.

  • Solid-State Properties of Hexaazatriphenylenehexacarbonitrile HAT(CN)6.- Radical Anions in Crystalline Salts Containing Cryptand(M+ ) and Crystal Violet Cations.
    Chemistry (Weinheim an der Bergstrasse Germany), 2020
    Co-Authors: Dmitri V Konarev, Salavat S Khasanov, Alexey V. Kuzmin, Akihiro Otsuka, Hideki Yamochi, Hiroshi Kitagawa, Maxim V. Mikhailenko, Rimma N Lyubovskaya
    Abstract:

    Crystalline {Cryptand[2.2.2](Na+ )}{HAT(CN)6.- }⋅0.5C6 H4 Cl2 (1), {Cryptand[2.2.2](K+ )}{HAT(CN)6.- } (2), (CV+ ){HAT(CN)6.- } (3), and (CV+ ){HAT(CN)6.- }⋅2C6 H4 Cl2 (4) salts (where CV+ is the crystal violet cation) containing hexaazatriphenylenehexacarbonitrile radical anions have been obtained. The solid-state molecular structure as well as the optical and magnetic properties of HAT(CN)6.- are studied. The formation of HAT(CN)6.- in 1-4 leads to the appearance of new bands in the visible range, at 694 and 740 nm. The HAT(CN)6.- radical anions have spin state S=1/2 and are packed in one-dimensional stacks containing the {HAT(CN)6.- }2 dimers alternated with weaker interacting pairs of HAT(CN)6.- in 1 and nearly isolated {HAT(CN)6.- }2 dimers in 2. The {HAT(CN)6.- }2 dimers are diamagnetic in 1 but they effectively mediate one-dimensional antiferromagnetic coupling of spins within the stacks with moderate exchange interaction of J/kB = -80 K. The behaviour of salt 2 is described by a singlet-triplet model for the {HAT(CN)6.- }2 dimers with an energy gap of 434(±7) K. Magnetic behaviour of both salts agree well with the data of extended Huckel calculations. Salts 3 and 4 contain isolated stacks of alternated HAT(CN)6.- and CV+ ions, and in this case, nearly paramagnetic behaviour is observed with Weiss temperatures of -1 and -7 K, respectively. Narrow Lorentzian EPR signals with g = 2.0033-2.0039 were found for the HAT(CN)6.- radical anions in 1 and 4 but in solution g-factor shifts to 1.9964. The electronic structure of HAT(CN)6.- is analysed based on X-ray diffraction data for 2, showing a Jahn-Teller distortion of the radical anion that reduces the symmetry from D3h to Cs and splits the initially degenerated LUMOs.

  • Decacyclene Radical Anions Showing Strong Low-energy Intramolecular Absorption and Magnetic Coupling of Spins in a Hexagonal Network.
    Chemistry an Asian journal, 2020
    Co-Authors: Dmitri V Konarev, Salavat S Khasanov, Akihiro Otsuka, Hideki Yamochi, Hiroshi Kitagawa, Aleksey V. Kuzmin, Alexander F. Shestakov, Rimma N Lyubovskaya
    Abstract:

    Two salts of the aromatic hydrocarbon decacyclene, {Cryptand[2.2.2](Cs+ )} (decacyclene.- ) (1) and {Bu3 MeP+ }(decacyclene.- ) (2), were obtained. In both salts, decacyclene.- radical anions formed channels occupied by cations. However, corrugated hexagonal decacyclene.- layers could be outlined in the crystal structure of 1 with several side-by-side C⋅⋅⋅C approaches. The decacyclene.- radical anions showed strong distortion in both salts, deviating from the C3 symmetry owing to the repulsion of closely arranged hydrogen atoms and the Jahn-Teller effect. Radical anions showed intense unusually low energy absorption in the IR-range, with maxima at 4800 and 6000 cm-1 . According to the carculations, these bands can originate from the SOMO-LUMO+1 and SOMO-LUMO+2 transitions, respectively. Radical anions exhibited a S=1/2 spin state, with an effective magnetic moment of 1.72 μB at 300 K. The decacyclene.- spin antiferromagnetically coupled with a Weiss temperature of -11 K. Spin ordering was not observed down to 1.9 K owing to spin frustration in the hexagonal decacyclene.- layers.

  • Double‐Decker Paramagnetic {(K)(H3Hhp)2}⋅2− Radical Dianions Comprising Two [30]Trithia‐2,3,5,10,12,13,15,20,22,23,25,30‐Dodecaazahexaphyrins and a Potassium Ion
    Chemistry an Asian journal, 2019
    Co-Authors: Dmitri V Konarev, Salavat S Khasanov, Rimma N Lyubovskaya, Akihiro Otsuka, Hideki Yamochi, Hiroshi Kitagawa, Mikhail K. Islyaikin, Evgenii N. Ivanov, Oskar I. Koifman, Yuriy A. Zhabanov
    Abstract:

    Reduction of free-base [30]trithia-2,3,5,10,12,13,15,20,22,23,25,30-dodecaazahexaphyrin (H3 Hhp) yields {Cryptand[2.2.2](K)}2 {(K)(H3 Hhp)2 }⋅4C6 H4 Cl2 (1) containing double-decker {(K)(H3 Hhp)2 }⋅2- radical dianions, whose structure was elucidated using X-ray diffraction. Potassium ion forms 12 short (K+ )⋅⋅⋅N(H3 Hhp) contacts with two H3 Hhp macrocycles in the 3.048-3.157 A range. Dianions have S=1/2 spin state manifesting an effective magnetic moment of 1.64 μB at 300 K and a narrow Lorentzian electron paramagnetic resonance signal. Quantum chemical calculations support the ionic nature of the (K+ )-N(H3 Hhp) interactions and the nearly equal distribution of the -1.5 charge over each macrocycle. H3 Hhp takes the role of an aza-crown ether in free-base reduced state and forms a new type of double-decker complex.

  • negatively charged singly bonded dimers of c1 c70 cf3 10 and bare c70 fullerene
    New Journal of Chemistry, 2019
    Co-Authors: Dmitri V Konarev, Victor A. Brotsman, Sergey I. Troyanov, Salavat S Khasanov, Alexey A Goryunkov, Ilya N Ioffe, Rimma N Lyubovskaya
    Abstract:

    Salts of fullerene derivative C1-C70(CF3)10 and bare fullerene C70 with cryptates of alkali metals as cations have been obtained: {Cryptand[2.2.2](K+)}2[C70(CF3)10−]2·Solvent (1), {Cryptand[2.2.2](K+)}2(C70−)2·Solvent (2) and {Cryptand[2.2.1](Na+)}2(C70−)2·3C6H4Cl2 (3) in the form of single crystals. Radical anions of both functionalized and bare fullerene C70 form diamagnetic and EPR silent singly-bonded [C70(CF3)10−]2 and (C70−)2 dimers stable at least up to room temperature (according to the EPR data). The length of the intercage C–C bonds and the center-to-center interfullerene distances are 1.570(7) and 10.516 A for the [C70(CF3)10−]2 dimer in 1 and 1.576(4)–1.587(4) A and 10.493–10.507 A for the (C70−)2 dimers in 2 and 3. Optical spectra of 1–3 manifest new bands in the NIR range characteristic of negatively charged fullerenes. These bands are blue shifted in the spectrum of 1 with [C70(CF3)10−]2 in comparison with the spectrum of underivatized C70˙−. It is shown that negatively charged fullerene dimers show new low-energy broad absorption bands in the NIR range most probably associated with charge transfer between fullerene anions within the dimers. According to DFT calculations, the singly-bonded [C70(CF3)10−]2 dimer demonstrates negative binding energy in the gas phase, but becomes bound by 54 kJ mol−1 when the solvent effects are taken into account via the D-PCM model. Charge asymmetry incurred by CF3 groups at the pole region of anionic C1-C70(CF3)10 promotes its dimerization in the condensed phase.

  • Molecular structures, and optical and magnetic properties of free-base tetrapyrazinoporphyrazine in various reduction states
    New Journal of Chemistry, 2019
    Co-Authors: Dmitri V Konarev, Salavat S Khasanov, Maxim A. Faraonov, Alexey V. Kuzmin, Nikita G. Osipov, Akihiro Otsuka, Hideki Yamochi, Hiroshi Kitagawa, Rimma N Lyubovskaya
    Abstract:

    Reduction of free-base tetrapyrazinoporphyrazine (H2TPyzPz) under different experimental conditions allowed us to obtain radical anion salt {Cryptand[2.2.2](K+)}2(H2TPyzPz˙−)2·3C6H4Cl2 (1), and dianion salts {Cryptand[2.2.2](K+)}2(H2TPyzPz2−)·C6H4Cl2 (2) and {Cryptand[2.2.2](K+)}2(H2TPyzPz2−)·[CpFe(CO)2]2·3C6H4Cl2 (3) in the form of single crystals. The molecular structure, and optical and magnetic properties of free-base tetrapyrazinoporphyrazine in various reduction states were studied for the first time. Reduction of the macrocycle is accompanied by the appearance of alternation of the C–Nmeso bonds, blue shift of both the Soret and Q-bands and the appearance of new bands in the NIR range. Salt 1 contained paramagnetic H2TPyzPz˙− radical anions half of which formed face-to-face type dimers with very effective π–π interaction, whereas the rest were magnetically isolated from the other H2TPyzPz˙− radical anions. Strong antiferromagnetic coupling of spins with a magnetic exchange interaction of J/kB = −140 K was observed in these dimers. In 2 and 3, diamagnetic dianions H2TPyzPz2− were completely isolated.