Frank Haarmann

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Equiatomic AEAuX (AE=Ca−Ba, X=Al−In) Intermetallics: A Systematic Study of their Electronic Structure and Spectroscopic Properties

Christopher Benndorf, Frank Stegemann, Stefan Seidel, Lea Schubert, more

Chemistry – A European Journal > 23 > 17 > 4187 - 4196

The three intermetallic compounds SrAuGa, BaAuAl and BaAuGa were synthesised from the elements in niobium ampoules. The Sr compound crystallises in the orthorhombic KHg₂‐type structure (Imma, a=465.6(1), b=771.8(2), c=792.6(2) pm, wR₂=0.0740, 324 F² values, 13 variables), whereas the Ba compounds were both found to crystallise in the cubic non‐centrosymmetric LaIrSi‐type structure (P2₁3, BaAuAl: a=...

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Unravelling Local Atomic Order of the Anionic Sublattice in M(Al_1−xGa_x)₄ with M=Sr and Ba by Using NMR Spectroscopy and Quantum Mechanical Modelling

Oliver Pecher, Bernhard Mausolf, Volker Peters, Kevin Lamberts, more

Chemistry – A European Journal > 22 > 49 > 17833 - 17842

The quasibinary section of the intermetallic phases MAl₄ and MGa₄ with M=Sr and Ba have been characterised by means of X‐ray diffraction (XRD) studies and differential thermal analysis. The binary phases show complete miscibility and form solid solutions M(Al_1−xGa_x)₄ with M=Sr and Ba. These structures crystallise in the BaAl₄ structure type with four‐ and five‐bonded Al and/or Ga atoms (denoted as...

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Zintl Phases K_4–xNa_xSi₄ (1 ≤ x ≤ 2.2) and K₇NaSi₈: Synthesis, Crystal Structures, and Solid‐State NMR Spectroscopic Investigations

Lavinia M. Scherf, Oliver Pecher, Kent J. Griffith, Frank Haarmann, more

European Journal of Inorganic Chemistry > 2016 > 28 > 4674 - 4682

The Zintl phases K_4–xNa_xSi₄ (1 ≤ x ≤ 2.2) and K₇NaSi₈ are the first representatives of the K–Na–Si system, and both contain tetrahedral [Si₄]^4– clusters and a charge‐balancing number of K⁺ and Na⁺ cations. All phases of K_4–xNa_xSi₄ (1 ≤ x ≤ 2.2) crystallize in a new structure type with space group P2₁/n, as determined by single‐crystal X‐ray diffraction analysis of the parent phase K₃NaSi₄. Rietveld...

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Inside Cover: The Solid Solution Sr_1−xBa_xGa₂: Substitutional Disorder and Chemical Bonding Visited by NMR Spectroscopy and Quantum Mechanical Calculations (Chem. Eur. J. 40/2015)

Oliver Pecher, Bernhard Mausolf, Kevin Lamberts, Dirk Oligschläger, more

Chemistry – A European Journal > 21 > 40 > 13826 - 13826

By combining solid‐state synthesis with elaborate experimental and theoretical techniques, F. Haarmann and co‐workers, in their Full Paper on page 13971 ff., have examined intermetallic phases. The combined application of X‐ray diffraction, solid‐state NMR spectroscopy, and density functional theory (DFT) offers insights into the local atomic environments. Synthesis of Sr_1−xBa_xGa₂ solid solution samples...

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The Solid Solution Sr_1−xBa_xGa₂: Substitutional Disorder and Chemical Bonding Visited by NMR Spectroscopy and Quantum Mechanical Calculations

Oliver Pecher, Bernhard Mausolf, Kevin Lamberts, Dirk Oligschläger, more

Chemistry – A European Journal > 21 > 40 > 13971 - 13982

Complete miscibility of the intermetallic phases (IPs) SrGa₂ and BaGa₂ forming the solid solution Sr_1−xBa_xGa₂ is shown by means of X‐ray diffraction, thermoanalytical and metallographic studies. Regarding the distances of Sr/Ba sites versus substitution degree, a model of isolated substitution centres (ISC) for up to 10 % cation substitution is explored to study the influence on the Ga bonding situation...

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The Zintl Phase Cs₇NaSi₈ – From NMR Signal Line Shape Analysis and Quantum Mechanical Calculations to Chemical Bonding

Oliver Pecher, Marco Esters, Arno Görne, Bernhard Mausolf, more

Zeitschrift für anorganische und allgemeine Chemie > 640 > 11 > 2169 - 2176

Powder samples as well as red and transparent single crystals of the Zintl phase Cs₇NaSi₈ were synthesized and characterized by means of X‐ray diffraction and differential thermal analysis. Cs₇NaSi₈ was found to be isotypic to the recently reported phase Rb₇NaSi₈. It crystallizes in the Rb₇NaGe₈ structure type forming trigonal pyramidal Si₄^4– anions. Two unique environments of the cations are observed,...

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Intermetallic Compounds with Multiple Yttrium Sites – An ⁸⁹Y Solid State NMR Spectroscopic Study

Christoph Höting, Hellmut Eckert, Frank Haarmann, Rainer Pöttgen

Zeitschrift für anorganische und allgemeine Chemie > 640 > 7 > 1303 - 1308

The intermetallic compounds Y₂RuB₆, Y₂ReB₆, Y₂RhSi₃, YRh₂Si, and YPdSi were synthesized from the elements by arc‐melting and subsequent annealing in sealed silica ampoules. The samples were studied by X‐ray diffraction on powders. The structures of Y₂RuB₆ and Y₂RhSi₃ were refined from single crystal diffraction data: Y₂ReB₆ type, Pbam, a = 916.3(2) pm, b = 1150.3(3) pm, c = 364.37(9) pm, wR₂ = 0...

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NaRb₇(Si_4–xGe_x)₂ – Soluble Zintl Phases Containing Heteroatomic Tetrahedral [Si_4–xGe_x]^4– Clusters

Markus Waibel, Oliver Pecher, Bernhard Mausolf, Frank Haarmann, more

European Journal of Inorganic Chemistry > 2013 > 32 > 5541 - 5546

The quaternary phases NaRb₇(Si_4–xGe_x)₂ (x = 1–3) crystallize with an NaRb₇Ge₈‐type structure and contain tetrahedral four‐atom clusters that consist of Si and Ge atoms. The quaternary phases possess larger cell volumes with increasing Ge amount. The formation of heteroatomic [Si_4–xGe_x]^4– clusters is indicated by chemically different Si environments, which were analyzed by means of solid‐state ²⁹Si...

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Crystal‐to‐Crystal Transformations in a Seven‐Coordinated Scandium Complex

Carina Merkens, Oliver Pecher, Friedrich Steuber, Sascha Eisenhut, more

Zeitschrift für anorganische und allgemeine Chemie > 639 > 2 > 340 - 346

Aquatris(3‐cyanopentane‐2, 4‐dionato)scandium(III) undergoes two transformations which can be monitored by X‐ray diffraction as well as solid‐state NMR spectroscopy: At 145 K, the mononuclear complex shows a reversible phase transition; in agreement with the symmetry principle, this transition of the t₂ type proceeds from the monoclinic room temperature phase to triclinic twins at low temperature,...

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Ga Bonding Variability in Ca_1–xGa_2+3x Visited by Solid State NMR Spectroscopy

Oliver Pecher, Frank Haarmann

Zeitschrift für anorganische und allgemeine Chemie > 638 > 10 > 1622 - 1622

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The Silicides M₄Si₄ with M = Na, K, Rb, Cs, and Ba₂Si₄ – NMR Spectroscopy and Quantum Mechanical Calculations

Thorsten Goebel, Alim Ormeci, Oliver Pecher, Frank Haarmann

Zeitschrift für anorganische und allgemeine Chemie > 638 > 10 > 1437 - 1445

The Zintl phases M₄Si₄ with M = Na, K, Rb, Cs, and Ba₂Si₄ feature a common structural unit, the Si₄^4– anion. The coordination of the anions by the cations varies significantly. This allows a systematic investigation of the bonding situation of the anions by ²⁹Si NMR spectroscopy. The compounds were characterized by powder X‐ray diffraction, differential thermal analysis, magnetic susceptibility measurements,...

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Solid State NMR Spectroscopy on Mn₃C

Sascha Eisenhut, Ludwig Stork, Jörg von Appen, Richard Dronskowski, more

Zeitschrift für anorganische und allgemeine Chemie > 638 > 10 > 1567 - 1567

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A Clathrate‐I Phase with Li–Ge Framework

Ying Liang, Bodo Böhme, Alim Ormeci, Horst Borrmann, more

Chemistry – A European Journal > 18 > 32 > 9818 - 9822

A clathrate containing lithium: K₈Li_xGe_44−x/4□_2−3x/4 constitutes the first intermetallic clathrate‐I containing lithium. Different to the clathrate phases formed with other alkali metals, Li does not occupy positions within the polyhedral cages but substitutes Ge in the host framework.

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Synthesis, Crystal Structure and Chemical Bonding of the Zintl Phase Rb₇NaSi₈

Thorsten Goebel, Yurii Prots, Alim Ormeci, Oliver Pecher, more

Zeitschrift für anorganische und allgemeine Chemie > 637 > 13 > 1982 - 1991

Abstract. The Zintl phase Rb₇NaSi₈ was synthesized as single‐phase material. Powder and single‐crystal X‐ray diffraction, thermal analysis, chemical analysis, measurement of the magnetic susceptibility, and ²³Na, ²⁹Si, and ⁸⁷Rb nuclear magnetic resonance (NMR) spectroscopy were employed to characterize the material. Rb₇NaSi₈ crystallizes in the Rb₇NaGe₈ type of structure forming trigonal pyramidal...

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NMR Spectroscopy of Intermetallic Compounds: An Experimental and Theoretical Approach to Local Atomic Arrangements in Binary Gallides

Frank Haarmann, Katrin Koch, Peter Jeglič, Oliver Pecher, more

Chemistry – A European Journal > 17 > 27 > 7560 - 7568

The results of the investigation of MGa₂ with M=Ca, Sr, Ba and of MGa₄ with M=Na, Ca, Sr, Ba by a combined application of NMR spectroscopy and quantum mechanical calculations are comprehensively evaluated. The electric‐field gradient (EFG) was identified as the most reliable measure to study intermetallic compounds, since it is accessible with high precision by quantum mechanical calculations and,...

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Sr_1‐xBa_xGa₂: NMR Spectroscopy

Oliver Pecher, Frank Haarmann

Zeitschrift für anorganische und allgemeine Chemie > 636 > 11 > 2089 - 2089

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Atomistic Characterisation of Li⁺ Mobility and Conductivity in Li_7−xPS_6−xI_x Argyrodites from Molecular Dynamics Simulations, Solid‐State NMR, and Impedance Spectroscopy

Oliver Pecher, Shiao‐Tong Kong, Thorsten Goebel, Vera Nickel, more

Chemistry – A European Journal > 16 > 28 > 8347 - 8354

The atomistic mechanisms of Li⁺ ion mobility/conductivity in Li_7−xPS_6−xI_x argyrodites are explored from both experimental and theoretical viewpoints. Ionic conductivity in the title compound is associated with a solid–solid phase transition, which was characterised by low‐temperature differential scanning calorimetry, ⁷Li and ¹²⁷I NMR investigations, impedance measurements and molecular dynamics simulations...

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Synthesis, Crystal Structure and Lithium Motion of Li₈SeN₂ and Li₈TeN₂

Daniel Bräunling, Oliver Pecher, Dmytro M. Trots, Anatoliy Senyshyn, more

Zeitschrift für anorganische und allgemeine Chemie > 636 > 6 > 936 - 946

The compounds Li₈EN₂ with E = Se, Te were obtained in form of orange microcrystalline powders from reactions of Li₂E with Li₃N. Single crystal growth of Li₈SeN₂ additionally succeeded from excess lithium. The crystal structures were refined using single‐crystal X‐ray diffraction as well as X‐ray and neutron powder diffraction data (I4₁md, No. 109, Z = 4, Se: a = 7.048(1) Å, c = 9.995(1) Å, Te: a =...

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Copper‐Containing SiCN Precursor Ceramics (Cu@SiCN) as Selective Hydrocarbon Oxidation Catalysts Using Air as an Oxidant

Germund Glatz, Thomas Schmalz, Tobias Kraus, Frank Haarmann, more

Chemistry – A European Journal > 16 > 14 > 4231 - 4238

A molecular approach to metal‐containing ceramics and their application as selective heterogeneous oxidation catalysts is presented. The aminopyridinato copper complex [Cu₂(Ap^TMS)₂] (Ap^TMSH=(4‐methylpyridin‐2‐yl)trimethylsilanylamine) reacts with poly(organosilazanes) via aminopyridine elimination, as shown for the commercially available ceramic precursor HTT 1800. The reaction was studied by ¹H and...

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Facile Scalable Synthesis of Rectorites

Michael W. Möller, Dunja Hirsemann, Frank Haarmann, Jürgen Senker, more

Chemistry of Materials > 2010 > 22 > 1 > 186 - 196

INFONA - science communication portal

Search results for: Frank Haarmann

Equiatomic AEAuX (AE=Ca−Ba, X=Al−In) Intermetallics: A Systematic Study of their Electronic Structure and Spectroscopic Properties

Unravelling Local Atomic Order of the Anionic Sublattice in M(Al_1−xGa_x)₄ with M=Sr and Ba by Using NMR Spectroscopy and Quantum Mechanical Modelling

Zintl Phases K_4–xNa_xSi₄ (1 ≤ x ≤ 2.2) and K₇NaSi₈: Synthesis, Crystal Structures, and Solid‐State NMR Spectroscopic Investigations

Inside Cover: The Solid Solution Sr_1−xBa_xGa₂: Substitutional Disorder and Chemical Bonding Visited by NMR Spectroscopy and Quantum Mechanical Calculations (Chem. Eur. J. 40/2015)

The Solid Solution Sr_1−xBa_xGa₂: Substitutional Disorder and Chemical Bonding Visited by NMR Spectroscopy and Quantum Mechanical Calculations

The Zintl Phase Cs₇NaSi₈ – From NMR Signal Line Shape Analysis and Quantum Mechanical Calculations to Chemical Bonding

Intermetallic Compounds with Multiple Yttrium Sites – An ⁸⁹Y Solid State NMR Spectroscopic Study

NaRb₇(Si_4–xGe_x)₂ – Soluble Zintl Phases Containing Heteroatomic Tetrahedral [Si_4–xGe_x]^4– Clusters

Crystal‐to‐Crystal Transformations in a Seven‐Coordinated Scandium Complex

Ga Bonding Variability in Ca_1–xGa_2+3x Visited by Solid State NMR Spectroscopy

The Silicides M₄Si₄ with M = Na, K, Rb, Cs, and Ba₂Si₄ – NMR Spectroscopy and Quantum Mechanical Calculations

Solid State NMR Spectroscopy on Mn₃C

A Clathrate‐I Phase with Li–Ge Framework

Synthesis, Crystal Structure and Chemical Bonding of the Zintl Phase Rb₇NaSi₈

NMR Spectroscopy of Intermetallic Compounds: An Experimental and Theoretical Approach to Local Atomic Arrangements in Binary Gallides

Sr_1‐xBa_xGa₂: NMR Spectroscopy

Atomistic Characterisation of Li⁺ Mobility and Conductivity in Li_7−xPS_6−xI_x Argyrodites from Molecular Dynamics Simulations, Solid‐State NMR, and Impedance Spectroscopy

Synthesis, Crystal Structure and Lithium Motion of Li₈SeN₂ and Li₈TeN₂

Copper‐Containing SiCN Precursor Ceramics (Cu@SiCN) as Selective Hydrocarbon Oxidation Catalysts Using Air as an Oxidant

Facile Scalable Synthesis of Rectorites

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