Zoran Mazej

University of Warsaw, Warsaw, Masovian Voivodeship, Poland

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Publications (108)227.2 Total impact

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    ABSTRACT: AgF1–xClx phases showing substantial disorder of anionic sublattice have been prepared and characterized for the first time.
    Journal of Fluorine Chemistry 09/2014; · 1.94 Impact Factor
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    ABSTRACT: Crystals of [ImH]2[TiF6]·2HF (I) (Im: imidazole), [ImH]3[Ti2F11] (II), [ImH]4[Ti4F20] (III), [ImH3][Ti5F23] (IV), and [ImH][Ti2F9] (V) are prepared from stoichiometric mixtures of imidazole and TiF4 in anhydrous HF (-196 °C followed by warming to ambient temperature) and characterized by single crystal XRD, Raman spectroscopy, and quantum chemical B3LYP calculations.
    ChemInform 10/2013; 44(40).
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    ABSTRACT: Reactions between imidazole (Im, C3H4N2) and TiF4 in anhydrous hydrogen fluoride (aHF) in different molar ratios have yielded [ImH]2[TiF6]·2HF, [ImH]3[Ti2F11], [ImH]4[Ti4F20], [ImH]3[Ti5F23], and [ImH][Ti2F9] upon crystallization. All five structures were characterized by low-temperature single-crystal X-ray diffraction. The single-crystal Raman spectra of [ImH]4[Ti4F20], [ImH]3[Ti5F23], and [ImH][Ti2F9] were also recorded and assigned. In the crystal structure of [ImH]2[TiF6]·2HF, two HF molecules are coordinated to each [TiF6](2-) anion by means of strong F-H···F hydrogen bonds. The [Ti2F11](3-) anion of [ImH]3[Ti2F11] results from association of two TiF6 octahedra through a common fluorine vertex. Three crystallographically independent [Ti2F11](3-) anions, which have distinct geometries and orientations, are hydrogen-bonded to the [ImH](+) cations. The [ImH]4[Ti4F20] salt crystallized in two crystal modifications at low (α-phase, 200 K) and ambient (β-phase, 298 K) temperatures. The tetrameric [Ti4F20](4-) anion of [ImH]4[Ti4F20] consists of rings of four TiF6 octahedra, which each share two cis-fluorine vertices, whereas the pentameric [Ti5F23](3-) anion of [ImH]3[Ti5F23] results from association of five TiF6 units, where four of the TiF6 octahedra share two cis-vertices, forming a tetrameric ring as in [Ti4F20](4-), and the fifth TiF6 unit shares three fluorine vertices with three TiF6 units of the tetrameric ring. The [ImH][Ti2F9] salt also crystallizes in two crystal modifications at low (α-phase, 200 K) and high (β-phase, 298 K) temperatures and contains polymeric ([Ti2F9](-))∞ anions, which appear as two parallel infinite zigzag chains comprised of TiF6 units, where each TiF6 unit of one chain is connected to a TiF6 unit of the second chain through a shared fluorine vertex. Quantum-chemical calculations at the B3LYP/SDDALL level of theory were used to arrive at the gas-phase geometries and vibrational frequencies of the [Ti4F20](4-) and [Ti5F23](3-) anions, which aided in the assignment of the experimental vibrational frequencies of the anion series.
    Inorganic Chemistry 07/2013; · 4.59 Impact Factor
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    ABSTRACT: We demonstrate that the intrinsic electron doping of monolayer epitaxial graphene on SiC(0001) can be tuned in a controlled fashion to holes via molecular doping with the fluorinated fullerene C60F48. In situ angle-resolved photoemission is used to measure an upward shift of (0.6 ± 0.05) eV in the Dirac point from −0.43 eV to +0.17 eV relative to the Fermi level. The carrier density is observed to change from n ∼ (1 × 1013 ± 0.1 × 1013) cm−2 to p ∼ (2 × 1012 ± 1 × 1012) cm−2. We introduce a doping model employing Fermi-Dirac statistics which explicitly takes temperature and the highly correlated nature of molecular orbitals into account. The model describes the observed doping behaviour in our experiment and readily explains why net p-type doping was not achieved in a previous study [Coletti et al., Phys. Rev. B 81, 8 (2010)] which used tetrafluorotetra-cyanoquinodimethane (F4-TCNQ).
    Applied Physics Letters 06/2013; 102:241601. · 3.52 Impact Factor
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    ABSTRACT: The crystal structures of three new HF solvates of fluoroanion salts of alkali metal ions are reported, K2(HF)TiF6, K2(HF)3B12F12, and Cs2(HF)B12F12. The anion packing in K2(HF)TiF6 (P21/m) is distorted cubic close-packed with Ti⋯Ti distances that range from 5.717(1) to 7.394(1) Å (average 6.18 Å). Half of the K+ ions are in Td holes and half are in Oh holes (i.e., this is a distorted version of the Cs2S structure). Each HF molecule is bonded to a K+ ion in the Oh holes (KF(H) = 2.679(5) Å) and also weakly interacts with two other K+ ions in adjacent Oh holes (K⋯F(H) = 3.238(2) Å). The anion packing in K2(HF)3B12F12 (Fm3¯m) is simple cubic. The (B12 centroid)⋯(B12 centroid) distance (⊙⋯⊙ distance) is 7.242 Å, and disordered K2(μ-HF)32+ cations occupy each cube. The anion packing in Cs2(HF)B12F12 (P21/c) is distorted hexagonal close-packed with ⊙⋯⊙ distances that range from 7.217 to 9.408 Å (average 8.304 Å). The HF molecule bridges Cs+ ions in adjacent Oh holes, forming infinite Cs+(μ-HF)Cs+(μ-HF) chains. The other half of the Cs+ ions are in Td holes, displaced nearly 1 Å from the center of those holes. This structure is similar to the distorted Ni2In structure exhibited by Cs2(H2O)B12F12. The new results are used to compare and contrast the strength of M–F(H) interactions with M–F interactions involving F atoms from fluoroanions as well as the solid-state packing of icosahedral B12F122− anions and octahedral MF62− anions in alkali-metal salts, both with and without the inclusion of weakly-basic HF solvent molecules.
    Journal of Fluorine Chemistry 05/2013; 145:118–127. · 1.94 Impact Factor
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    ABSTRACT: High-purity samples of potassium trifluoroargentate(ii), KAgF3, have been obtained via a novel synthetic pathway. This compound is found to exhibit an order-disorder phase transition around 230 K. Susceptibility measurements indicate that KAgF3 exhibits strong antiferromagnetic (AFM) coupling reminiscent of that found in copper(ii) oxides.
    Chemical Communications 04/2013; · 6.38 Impact Factor
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    ABSTRACT: X-ray diffraction study of KTiF·8HF and RbTiF·6HF reveals a novel type of octameric cubic [MF] anion built from eight MF octahedra.
    Chemical Communications 03/2013; 49(26):2703-5. · 6.38 Impact Factor
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    ABSTRACT: Surface lattice defects would act as active sites for electrochemical reduction of propylene carbonate (PC) as a solvent for lithium ion battery. Effect of surface chlorination of natural graphite powder has been investigated to improve charge/discharge characteristics of natural graphite electrode in PC-containing electrolyte solution. Chlorination of natural graphite increases not only surface chlorine but also surface oxygen, both of which would contribute to the decrease in surface lattice defects. It has been found that surface-chlorinated natural graphite samples with surface chlorine concentrations of 0.5-2.3 at% effectively suppress the electrochemical decomposition of PC, highly reducing irreversible capacities, i.e. increasing first coulombic efficiencies by 20-30% in 1 mol L-1 LiClO4-EC/DEC/PC (1:1:1 vol.). In 1 mol L-1 LiPF6-EC/EMC/PC (1:1:1 vol.), the effect of surface chlorination is observed at a higher current density. This would be attributed to decrease in surface lattice defects of natural graphite powder by the formation of covalent C-Cl and C=O bonds.
    Acta Chimica Slovenica 01/2013; 60(3):513-20. · 1.14 Impact Factor
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    ABSTRACT: Lanthanoid(III) hexafluoroarsenates with AsF3 as a ligand were prepared with the reactions of solutions of Ln(AsF6)3 in anhydrous hydrogen fluoride and AsF3. Solid products with composition Ln(AsF3)3(AsF6)3 (Ln = La, Nd, Sm, Eu, Gd, Tb, Er, Tm) were isolated at 233 K. The attempt to prepare corresponding Yb and Lu compounds failed. Single crystals of Ln(AsF3)3(AsF6)3 (Ln = Ce, Pr) were prepared by the reaction of LnF3 (Ln = Ce, Pr) with AsF5 and aHF under solvothermal conditions above critical temperature of AsF5. During the crystallization the reduction of some AsF5 occurred and AsF3 was formed. Compounds crystallize in a hexagonal crystal system, space group P 6- 2c (a = 10.6656(7) Å (Ce); 10.6383(7) Å (Pr); c = 10.9113(9) Å (Ce), 10.878(2) Å (Pr); V = 1074.9(1) Å3 (Ce), 1066.2(2) Å3 (Pr); Z = 2). Ln atoms are coordinated by nine fluorine atoms in the shape of the tri-capped trigonal prism and are further connected in three-dimensional framework via trans bridging AsF6 units. Three fluorine atoms are provided by AsF3 (capped positions) and six by AsF6 units. X-ray powder analysis of Ln(AsF3)3(AsF6)3 (Ln = La, Nd, Sm, Eu, Gd, Tb, Er, Tm) show that they are isostructural with corresponding Ce and Pr compounds.
    Acta Chimica Slovenica 01/2013; 60(3):537-42. · 1.14 Impact Factor
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    ABSTRACT: Here we redetermine the crystal structure of Ag(II)SO4, an unusual d9 system, at 1 atm from powder X-ray data and we report hydrostatic pressure X-ray diffraction experiments on Ag(II)SO4 inside the diamond anvil cell. AgSO4 crystallizes in the monoclinic C2/c cell, with a = 12.8476(2) Å, b = 13.6690(4) Å, c = 9.36678(19) Å, β = 47.5653(13)°, and V = 1214.04(5) Å3 (Z = 16). AgSO4 exhibits bulk modulus, B0, of 36.9 GPa, and undergoes sluggish decomposition at 23 GPa yielding a high-pressure phase of Ag2S2O7 (K2S2O7-type), with the substrate and product coexisting at 30 GPa. Theoretical calculations within Density Functional Theory for the C2/c cell nicely reproduce the observed trend for lattice constants as well as the B0 values of AgSO4, and suggest that the rigidity of the infinite [Ag(SO4)] chains as well as the Jahn–Teller effect for the Ag(II) cation persist even at 30 GPa.
    CrystEngComm 11/2012; 15(1):192-198. · 3.88 Impact Factor
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    ABSTRACT: Disodium tetrafluoroargentate(ii) (Na(2)AgF(4)) has been synthesized by the thermal decomposition of NaAg(iii)F(4) in the presence of NaF. This novel synthetic pathway yielded a high-purity product which enabled determination of the crystal structure and magnetic properties of this compound. The crystal structure of Na(2)AgF(4) contains infinite [AgF(2+4/2)](2-) chains, in analogy to β-K(2)AgF(4), but with a different packing of chains. The unusually short Ag(2+)Ag(2+) contact of 3.342 Å within the chain is the shortest Ag(2+)Ag(2+) distance among all structurally characterized compounds of divalent silver. This structural feature is responsible for the 1D antiferromagnetic properties of Na(2)AgF(4) as determined from powder magnetic susceptibility measurements. These findings are rationalized with the aid of calculations of magnetic coupling constants within the framework of the Density Functional Theory including on-site Coulomb repulsion (DFT+U).
    Dalton Transactions 11/2012; · 3.81 Impact Factor
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    ABSTRACT: The title compounds are characterized by single crystal XRD, Raman spectroscopy, and magnetic measurements.
    ChemInform 07/2012; 43(27).
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    ABSTRACT: Trifluoromethansulfonate of silver(I), AgSO(3)CF(3) (abbreviated AgOTf), extensively used in organic chemistry, and its fluorosulfate homologue, AgSO(3)F, have been structurally characterized for the first time. The crystal structures of both homologues differ substantially from each other. AgOTf crystallizes in a hexagonal system (R3 space group, No.148) with a = b = 5.312(3) Å and c = 32.66(2) Å, while AgSO(3)F crystallizes in a monoclinic system in the centrosymmetric P2(1)/m space group (No.11) with a = 5.4128(10) Å, b = 8.1739(14) Å, c = 7.5436(17) Å, and β = 94.599(18)°, adopting a unique structure type (100 K data). There are two types of fluorosulfate anions in the structure; in one type the F atom is engaged in chemical bonding to Ag(I) and in the other type the F atom is terminal; accordingly, two resonances are seen in the (19)F NMR spectrum of AgSO(3)F. Theoretical analysis of the electronic band structure and electronic density of states, as well as assignment of the mid- and far-infrared absorption and Raman scattering spectra for both compounds, have been performed based on the periodic DFT calculations. AgSO(3)F exhibits an unusually low melting temperature of 156 °C and anomalously low value of melting heat (ca. 1 kJ mol(-1)), which we associate with (i) disorder of its anionic sublattice and (ii) the presence of 2D sheets in the crystal structure, which are weakly bonded with each other via long Ag-O(F) contacts. AgSO(3)F decomposes thermally above 250 °C, yielding mostly Ag(2)SO(4) and liberating SO(2)F(2). AgOTf is much more thermally stable than AgSO(3)F; it undergoes two consecutive crystallographic phase transitions at 284 °C and 326 °C followed by melting at 383 °C; its thermal decomposition commences above 400 °C leading at 500 °C to crystalline Ag(2)SO(4) and an unidentified phase as major products of decomposition in the solid state.
    Dalton Transactions 12/2011; 41(7):2034-47. · 3.81 Impact Factor
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    ABSTRACT: Hg(AuF6)2 crystallizes at 200 K in the orthorhombic space group Pbcn (No. 60) with a = 917.67(7) pm, b = 971.59(8) pm, c = 962.04(8) pm, and Z = 4. Mercury atoms are coordinated by eight fluorine atoms with six short and two long Hg-F contacts. HgF8 polyhedra share their four vertices and two edges with six AuF6 units forming a tridimensional framework. The results of X-ray diffraction analysis on single crystals of AgFAuF6 are in agreement with previously known powder X-ray diffraction data (Casteel et al, J. Solid State Chem. 96 (1992) 84-96). AgFAuF6 crystallizes orthorhombic in the space group Pnma (No. 62), a = 717.06(7) pm, b = 761.67(7) pm, c = 1013.61(10) pm at 200 K, Z = 4.
    Journal of Fluorine Chemistry 11/2011; 132(10):686-689. · 1.94 Impact Factor
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    ABSTRACT: Decomposition of hydrazinium pentafluoroaluminate under oxidative (F2) conditions leads to aluminium(III) fluoride whose properties are highly dependent on the conditions used for synthesis. In the presence of anhydrous HF, which probably acts as a heat exchange agent, samples have high BET areas, whereas BET areas of samples prepared under gas–solid conditions are small. XPS data are consistent with the presence of Lewis acid centres but, more importantly, emphasise the importance of surface hydroxyl groups, particularly in high surface area compounds. Catalytic behaviour towards isomerisation of 1,1,2-trichlorotrifluoroethane and subsequent dismutations at moderate temperatures and towards room temperature dehydrochlorination of tert-butyl chloride has been demonstrated for some high BET samples; both reactions indicate that surface Lewis sites exist. Catalytic ability is inhibited by surface hydroxyl groups but is improved by prior fluorination of the surface with CCl2F2. Catalysis is inhibited also by the presence of ammonium fluoroaluminate, a by-product of the decomposition process. The [NH4]+ salt level can be reduced by washing with anhydrous HF.
    Journal of Fluorine Chemistry 11/2011; 132(10):703-712. · 1.94 Impact Factor
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    ABSTRACT: Silver(II) triflate, previously reported by Leung et al. in 1979 (Can. J. Chem., 1979, 57, 326–329), crystallizes in a triclinic Pcell with a = 4.9117(11) Å, b = 5.1136(10) Å, c = 11.033(3) Å, α = 79.955(14)°, β = 75.771(16)°, γ = 61.571(17)° and V = 235.68(10) Å3 and is isomorphous to Cu(SO3CF3)2. The compound has a layered structure with an interlayer separation of 10.67 Å; the van der Waals gaps open between the CF3groups from neighbouring sheets. Ag(II) is coordinated by six O atoms in the form of an elongated octahedron; the adjacent Ag2+ cations are linked via –OSO– bridges; direct –O– bridges are absent. The [Ag(II)(SO3CF3)2]∞ layers consist of one-dimensional chains which interact weakly with each other via longer AgOSO–Ag contacts. This results in a 1D rather than 2D antiferromagnetic ordering, which can be described via the Bonner–Fisher model with a superexchange constant, Jintra-chain, of 104 K (9.0 meV) per pair of interacting Ag2+ cations. The magnetic ordering persists even at room temperature leading to a broad ESR signal with g = 2.199. DFT calculations confirm the 1D character of electronic structure and antiferromagnetism residing within the [Ag(II)(SO3CF3)4/2]∞ chains with a |Jinter-chain|/|Jintra-chain| ratio of 10−3 to 10−2. The calculated indirect bandgap at the Fermi level of 1 eV opens between rather flat valence and conduction bands, which are predominated by contributions from Ag and O atoms. Ag(SO3CF3)2 is extremely sensitive to moisture and decomposes instantly when exposed to atmosphere. When dry, it rapidly decomposes thermally above 120 °C, but its slow exothermic decay to AgSO3CF3 takes place even at room temperature. Silver(II) triflate is also photosensitive and irradiating it with a 632.8 nm laser radiation at a power greater than 0.17 mW leads to its decomposition to Ag(I) triflate and Ag(I)2S2O7.
    CrystEngComm 10/2011; 13(22):6871-6879. · 3.88 Impact Factor
  • Chemistry 08/2011; 17(38):10524-7. · 5.93 Impact Factor
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    ABSTRACT: The known title compound crystallizes in the monoclinic space group P21/c with Z = 4 (powder XRD).
    Berichte der deutschen chemischen Gesellschaft 04/2011; 2011(16):2508 - 2516. · 2.94 Impact Factor

Publication Stats

124 Citations
227.20 Total Impact Points


  • 2003–2013
    • University of Warsaw
      • • Faculty of Chemistry
      • • Interdisciplinary Centre for Mathematical and Computational Modelling
      Warsaw, Masovian Voivodeship, Poland
  • 1998–2013
    • Jožef Stefan Institute
      • Department of Inorganic Chemistry and Technology K1
      Ljubljana, Ljubljana, Slovenia
  • 1999–2010
    • University of Ljubljana
      Lubliano, Ljubljana, Slovenia
  • 2009
    • Warsaw University of Technology
      Warszawa, Masovian Voivodeship, Poland
    • University of Nova Gorica
      Gorica, Nova Gorica, Slovenia
  • 2006
    • Kyoto University
      • Department of Fundamental Energy Science
      Kyoto, Kyoto-fu, Japan