Dominik Kurzydłowski, Marianna Derzsi, Armand Budzianowski, Zvonko Jagličić, Wiktor Koźmiński, Zoran Mazej, Wojciech Grochala
European Journal of Inorganic Chemistry
Volume 2010, Issue 19, pages 2919–2925, July 2010
Dediacted to the memory of Neil Bartlett
We report the crystal structure and magnetic properties of a novel β polymorph of K2AgF4. β-K2AgF4 is paramagnetic above 20 K and exhibits a low Curie temperature (θ < 5 K). Solid state DFT (GGA and GGA+U) calculations were performed to analyze the electronic and magnetic structure of β-K2AgF4 at 0 K/0 GPa, reproducing correctly the ferromagnetic (FM) semiconductor ground state with the band gap at the Fermi level of approximately 1.65eV. Furthermore, we show that the novel β form is thermodynamically favoured over the previously reported two-dimensional α form and can be formed either by slow spontaneous exothermic α to β phase transition occurring on heating or direct synthesis from KF and AgF2 at 300°C. The relative stability of the α and β phases is rationalized in terms of the size of the M+cation in the M2M′F4 series (M = Na, K, Cs, M′ = Cu, Ag) and the mismatch between [MF] and [M′F4/2] sublattices in the layered perovskite α form.
Anna Olejniczak, Michalina Anioła, Marek Szafrański, Armand Budzianowski and Andrzej Katrusiak
Cryst. Growth Des., 2013, 13 (7), pp 2872–2879 DOI: 10.1021/cg400276c
Wojciech Grochala, Michał Ksawery Cyrański, Mariana Derzsi, Tomasz Michałowski, Przemysław J. Malinowski, Zoran Mazej, Dominik Kurzydłowski, Wiktor Koźmiński, Armand Budzianowski and Piotr J. Leszczyński
Dalton Trans., 2012,41, 2034-2047 DOI: 10.1039/C1DT11747E
Crystal and electronic structure, lattice dynamics and thermal properties of Ag(I)(SO3)R (R = F, CF3)
Trifluoromethansulfonate of silver(I), AgSO3CF3 (abbreviated AgOTf), extensively used in organic chemistry, and its fluorosulfate homologue, AgSO3F, 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 (R space group, No.148) with a=b=5.312(3)Å and c=32.66(2)Å, while AgSO3F crystallizes in a monoclinic system in the centrosymmetric P21/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 (100K 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 19F NMR spectrum of AgSO3F. 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. AgSO3F 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 othervia long Ag–O(F) contacts. AgSO3F decomposes thermally above 250°C, yielding mostly Ag2SO4 and liberating SO2F2. AgOTf is much more thermally stable than AgSO3F; 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 Ag2SO4 and an unidentified phase as major products of decomposition in the solid state.
Piotr J. Leszczyński, Armand Budzianowski, Łukasz Dobrzycki, Michał K. Cyrański, Mariana Derzsia and Wojciech Grochala
Dalton Trans., 2012,41, 396-402 DOI: 10.1039/C1DT10744E
Unusual crystal structure of a Ag(I)
High purity samples of a [Ag(pyrazine)2]S2O8 complex were obtained using modified synthetic pathways. Di(pyrazine)silver(II) peroxydisulfate is sensitive to moisture forming [Ag(pyrazine)2](S2O8)(H2O) hydrate which degrades over time yielding HSO4− derivatives and releasing oxygen. One polymorphic form of pyrazinium hydrogensulfate, β–(pyrazineH+)(HSO4−), is found among the products of chemical decomposition together with unique [Ag(I)(pyrazine)]5(H2O)2(HSO4)2[H(SO4)2]. Chemical degradation of [Ag(pyrazine)2]S2O8 in the presence of trace amounts of moisture can explain the very low yield of wet synthesis (11–15%). Attempts have failed to obtain a mixed valence Ag(II)/Ag(I) pyrazine complex via partial chemical reductionof the [Ag(pyrazine)2]S2O8 precursor with a variety of inorganic and organic reducing agents, orvia controlled thermal decomposition. Thermal degradation of [Ag(pyrazine)2]S2O8 containing occluded water proceeds at T > 90°C via evolution of O2; simultaneous release of pyrazine andSO3 is observed during the next stages of thermal decomposition (120–285°C), while Ag2SO4 and Ag are obtained upon heating to 400–450°C.
Przemysław Jan Malinowski, Mariana Derzsi, Armand Budzianowski, Piotr J. Leszczyński, Bartłomiej Gaweł, Zoran Mazej and Wojciech Grochala
Issue Chemistry – A European Journal Volume 17, Issue 38, pages 10524–10527,
Chem. Eur. J., 17: 10524–10527. doi: 10.1002/chem.201101952
O2 at low expense from AgIISO4: Silver(II) sulfate provides the first example among metal sulfates of low-temperature “reductive” thermal decomposition, which results in AgI disulfate and molecular dioxygen. Despite the similarity of this reaction to the one known for peroxodisulfates (e.g., K2S2O8), the thermodynamics and kinetics of both processes are markedly different, and when compared they severely disobey Hammond’s rule (see scheme).
Karol J. Fijalkowski, Radostina V. Genova, Yaroslav Filinchuk, Armand Budzianowski, Mariana Derzsi, Tomasz Jaroń, Piotr J. Leszczyński and Wojciech Grochala
Dalton Trans., 2011,40, 4407-4413 OI: 10.1039/C0DT01491E
Na[Li(NH2BH3)2] first mixed-cation amidoborane
We describe the successful synthesis of the first mixed–cation (pseudoternary) amidoborane, Na[Li(NH2BH3)2], with theoretical hydrogen capacity of 11.1 wt%. Na[Li(NH2BH3)2] crystallizes triclinic (P) with a=5.0197(4)Å, b=7.1203(7)Å, c=8.9198(9)Å, α=103.003(6)°, β=102.200(5)°, γ=103.575(5)°, and V=289.98(5)Å3 (Z=2), as additionally confirmed by Density Functional Theory calculations. Its crystal structure is topologically different from those of its orthorhombic LiNH2BH3 and NaNH2BH3 constituents, with distinctly different coordination spheres of Li (3 N atoms and 1 hydride anion) and Na (6 hydride anions). Na[Li(NH2BH3)2], which may be viewed as a product of a Lewis acid (LiNH2BH3)/Lewis base (NaNH2BH3) reaction, is an important candidate for a novel lightweight hydrogen storage material. The title material decomposes at low temperature (with onset at 75°C, 6.0% mass loss up to 110°C, and an additional 3.0% up to 200°C) while evolving hydrogen contaminated with ammonia.
Andrew James Churchard, Michał Ksawery Cyranski, Łukasz Dobrzycki, Armand Budzianowski and Wojciech Grochala
Energy Environ. Sci., 2010,3, 1973-1978 DOI: 10.1039/C0EE00051E
Nickel macrocycles with complex hydrides—new avenues for hydrogen storage research
As part of an investigation into Ni(macrocycle) complexes as a new class of complex hydridehydrogen store catalysts, two isomers of the unusually stable nickel borohydride, Ni(cyclam)(BH4)2 (cyclam = 1,4,8,11-tetraazacyclotetradecane), have been isolated and characterised by means of single crystal X-ray diffraction, infrared spectroscopy, thermogravimetry andcalorimetry. trans-Ni(cyclam)(BH4)2 crystallizes monoclinic (P21/c, a=7.1397(5)Å, b=12.8109(7)Å, c=8.7041(5)Å, β=109.948(6)°, V=748.36(8)Å3, Z=2); cis-Ni(cyclam)(BH4)2crystallizes orthorhombic (Pnma, a=14.4512(7)Å, b=9.4625(6)Å, c=11.7824(7)Å, V=1611.18(16)Å3, Z=4, with static disorder). The compounds were found to be considerably more thermally stable than the unchelated relative, Ni(BH4)2, with the onset of decomposition for the trans isomer at 170°C, thus nearly 200 °C higher than the decomposition temperature of Ni(BH4)2. This spectacular stabilisation holds promise for related macrocycle complexes of late transition metals to be used as hydrogenation catalysts on an equal footing with their unligated early transition metal counterparts.
Armand Budzianowski and Andrzej Katrusiak
Acta Crystallographica Section B
Volume 58, Part 1 (February 2002)
Acta Cryst. (2002). B58, 125-133 [doi:10.1107/S0108768101017955]
Conformational disorder and inversions of the lactone ring induce structural transformations in the crystals of 6-hydroxy-4,4,5,7,8-pentamethyl-3,4-dihydrocoumarin, C14H18O3. The onset of ordering of the lactone ring at 300K proceeds continuously, changes the space group from P21/m to P21/c and doubles the unit cell; the abrupt inversion of the lactone rings at 225K changes the crystal translational symmetry in the (010) plane. The mechanism combining the molecular conformation and dynamics with the crystal structure, its symmetry, and phase transitions is presented.