Zoran Mazej

Jožef Stefan Institute, Lubliano, Ljubljana, Slovenia

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Publications (115)260.82 Total impact

  • Wojciech Grochala, Zoran Mazej
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    ABSTRACT: Silver is the heavier congener of copper in the Periodic Table, but the chemistry of these two elements is very different. While Cu(II) is the most common cationic form of copper, Ag(II) is rare and its compounds exhibit a broad range of peculiar physico-chemical properties. These include, but are not limited to: (i) uncommon oxidizing properties, (ii) unprecedented large mixing of metal and ligand valence orbitals, (iii) strong spin-polarization of neighbouring ligands, (iv) record large magnetic superexchange constants, (v) ease of thermal decomposition of its salts with O-, N- or C-ligands, as well as (vi) robust Jahn-Teller effect which is preserved even at high pressure. These intriguing features of the compounds of Ag(II) will be discussed here together with (vii) a possibility of electromerism (electronic tautomerism) for a certain class of Ag(II) salts. © 2015 The Author(s) Published by the Royal Society. All rights reserved.
    Philosophical transactions. Series A, Mathematical, physical, and engineering sciences. 03/2015; 373(2037).
  • Zoran Mazej, Evgeny Goreshnik
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    ABSTRACT: New types of [XeF5]+ salts, i.e., NO2XeF5(SbF6)2 and XeF5[Cu(SbF6)3], are derived from reactions between XeF5SbF6 and NO2SbF6 or Cu(SbF6)2, respectively. The crystal structure of the former consists of [NO2]+ and [XeF5]+ cations and [SbF6]- anions. The main feature of the crystal structure of XeF5[Cu(SbF6)3] are rings of CuF6 octahedra that share apexes with SbF6 octahedra connected into an infinite tridimensional framework. This arrangement leads to the formation of cavities within which [XeF5]+ cations are located. Raman spectra of both [NO2]+/[XeF5]+ and [XeF5]+/Cu2+ mixed-cation hexafluorido-antimonates(V) are reported herein.
    European Journal of Inorganic Chemistry 02/2015; · 2.97 Impact Factor
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    Dataset: Na2AgF4 SI
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    ABSTRACT: The syntheses and characterizations of mixed-cation fluorosulfates containing AgII ions are reported and add to the moderately well-known chemistry of AgII compounds. The compounds synthesized mostly show different structures and compositions. The mixed sodium–silver fluorosulfate is isostructural with Ag3(SO3F)4 (monoclinic P21/c, a = 5.2812 Å, b = 13.0473 Å, c = 19.3557 Å, and β = 100.970°) and has the composition (Ag0.05Na0.95)(Ag0.65Na0.35)AgII(SO3F)4. The mixed potassium–silver fluorosulfate does not correspond to KI2AgII(SO3F)4 but rather to KAgI2AgII(SO3F)5 [orthorhombic P2221, a = 6.4736(3) Å, b = 7.3915(4) Å, and c = 17.7736(10) Å]. Two rubidium–silver fluorosulfates form as a mixture, one corresponds to RbAgI2AgII(SO3F)5 [orthorhombic P2221, a = 6.4828(6) Å, b = 7.3551(7) Å, c = 18.0262(17) Å], and the other corresponds to RbAgII(SO3F)3 [monoclinic P21/m, a = 15.8152(14) Å, b = 15.4861(13) Å, c = 17.0211(14) Å, and β = 101.513(5)°]. The cesium fluorosulfate/silver(II) fluorosulfate phase diagram is exemplified by the CsAgII(SO3F)3 salt [triclinic P, a = 14.9241(5) Å, b = 9.7046(3) Å, c = 17.8465(7) Å, α = 109.116(2)°, β = 84.655(3)°, and γ = 119.171(3)°]. The IR and Raman spectra of the compounds were measured, and their thermal stability and magnetic properties have been determined. The MAgI2AgII(SO3F)5 systems show antiferromagnetic behavior with absolute superexchange constants of up to 19.1 meV for M = K, and ferromagnetism can be observed below 20–40 K for the MAg(SO3F)3 derivatives (M = Rb, Cs).
    Berichte der deutschen chemischen Gesellschaft 12/2014; · 2.97 Impact Factor
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    Zoran Mazej, Evgeny Goreshnik
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    ABSTRACT: The KM(AsF6)3 (M2+ = Mg, Co, Mn, Zn) and KCu(SbF6)3 compounds crystallize isotypically to previously known KNi(AsF6)3. The main features of the structure of these compounds are rings of MF6 octahedra sharing apexes with AsF6 octahedra connected into infinite tri-dimensional frameworks. In this arrangement cavities are formed where K+ cations are placed. Single crystals of CoSr5(AsF6)12·8HF were obtained as one of the products after the crystallization of 3KF/CoF2/SrF2 mixture in the presence of AsF5 in anhydrous HF. The CoSr5(AsF6)12·8HF is monoclinic, C/2c (No.15), with a = 26.773(5) Å, b = 10.087(2) Å, c = 21.141(5) Å, β = 93.296(13) °, V = 5699.9(19) Å3 at 200 K, and Z = 4. There are three crystallographically non-equivalent Sr2+ cations in the crystal structure of CoSr5(AsF6)12·8HF. The Sr1 is coordinated by ten fluorine atoms from eight different [AsF6]- anions, meanwhile Sr2 and Sr3 are bound to nine fluorine atoms provided by one HF and eight AsF6 units or by two HF and six AsF6 units, respectively. The Co2+ is coordinated distorted-octahedrally by six fluorine atoms from two HF molecules and four different AsF6 units. All those moieties in the crystal strucutre of [Co(HF)2]Sr[Sr(HF)]2[Sr(HF)2]2[AsF6]12 are connected into tridimensional framework. The CoSr5(AsF6)12·8HF is a unique example of compound where HF molecules are directly bound via fluorine atoms to two different metal centres.
    Zeitschrift für Kristallographie - Crystalline Materials. 12/2014; 230(2):123–130.
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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; · 1.95 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; · 4.79 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: Single crystals of the title compounds are prepared by slow evaporation of anhydrous HF solutions containing mixtures of KF or RbF and TiF4.
    ChemInform 06/2013; 44(23):no-no.
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    ABSTRACT: The crystal structures of the three new HF solvates K2(HF)TiF6 (I), K2(HF)3B12F12 (II), and Cs2(HF)3B12F12 (III) are determined by single crystal XRD.
    ChemInform 05/2013; 44(20):no-no.
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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. · 1.95 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. · 0.81 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. · 0.81 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. · 3.86 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; · 4.10 Impact Factor

Publication Stats

401 Citations
260.82 Total Impact Points

Institutions

  • 1998–2014
    • Jožef Stefan Institute
      • Department of Inorganic Chemistry and Technology K1
      Lubliano, Ljubljana, Slovenia
  • 2010–2013
    • University of Warsaw
      • Faculty of Chemistry
      Warsaw, Masovian Voivodeship, Poland
  • 1999–2010
    • University of Ljubljana
      Lubliano, Ljubljana, Slovenia
  • 2009
    • University of Nova Gorica
      Gorica, Nova Gorica, Slovenia
    • Warsaw University of Technology
      Warszawa, Masovian Voivodeship, Poland
  • 2006
    • Kyoto University
      • Department of Fundamental Energy Science
      Kyoto, Kyoto-fu, Japan
  • 2004
    • Pierre and Marie Curie University - Paris 6
      Lutetia Parisorum, Île-de-France, France