Dr. Stefanie Gärtner

Studies on alkali metal trielides ATr (A=Na, K, Rb, Cs; Tr=In, Tl)

Almost 90 years after the first description of the NaTl structure, the Zintl-Klemm concept occupies a central position in the description of intermetallic compounds consisting of the combination of an electropositive metal with elements to the right of the Zintl line (between groups 13 and 14 in the PSE). Interestingly, the element on which this concept is based, thallium, is located to the left of the Zintl line.

The oldest characterised Zintl phase is cubic sodium thallide, which was characterised by Zintl himself in very careful investigations using the methods possible at the time. Combinations of electropositive metals with thallium (thallides) can be understood as border crossers between classical intermetallic compounds and Zintl phases. As a heavy group 13 element to the left of the Zintl line, no classical polyanionic salts are to be expected here, but significant Tl-Tl interactions nevertheless appear to play a role in structure formation. In addition to isolated clusters, two- and three-dimensional networks are found, depending on the proportion and type of electropositive metal involved. In some cases, the thallium substructures formed can be explained using the classic Zintl-Klemm concept with formal transfer of the valence electrons of the electropositive element to thallium. In some cases, however, this description fails and the resulting compounds can be categorised as classical intermetallic compounds.

The aim of this project is to expand the structural chemistry of the elements thallium and indium in formally negative oxidation states. Special emphasis will be placed on the role of alkali metals in structure formation. When synthesising the compounds, we therefore usually use several alkali metals at the same time. The crystal structures provide a more precise insight into their contribution to structure formation.

Front Cover: Synthesis and characterization of ternary trielides Na7KTr4 [Tr=In or Tl] including [Tr4]8- tetrahedra M. Janesch, V.F. Schwinghammer, I.G. Shenderovich, S. Gärtner, Z. Anorg.      Allg. Chem., 649, e202300211.  DOI: 10.1002/zaac.202300211

Front Cover: Investigations on Tetragonally Distorted Sodium Thallide NaTl‐tI8 S. Tiefenthaler, M. Schlosser, F. Pielnhofer, I. G. Shenderovich, A. Pfitzner, S. Gärtner, Z. Anorg. Allg. Chem. 646, 77-77 (2020).            DOI:10.1002/zaac.202070031

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  [Tl7]7- Clusters in Mixed Alkali Metal Thallides Cs7.29K5.71Tl13 and Cs3.45K3.55

V.F. Schwinghammer, S. Gärtner, Inorg. Chem., 2024, DOI: 10.1021/acs.inorgchem.3c04034

• Synthesis and characterization of ternary trielides Na7KTr4 [Tr=In or Tl] icluding [Tl4]8- Tetrahedra

M. Janesch, V.F. Schwinghammer, I.G. Shenderovich, S. Gärtner, Z. Anorg. Allg. Chem., 2023, e202300112. DOI: 10.1002/zaac.202300112

• Na7RbTl4 — A New Ternary Zintl Phase Containing [Tl4]8– Tetrahedra

V.F. Schwinghammer, M. Janesch, N. Korber, S. Gärtner, Z. Anorg. Allg. Chem.,  2022, e202200332. DOI: 10.1002/zaac.202200332

• Single Crystal X-Ray Structure Analyses of Binary and Ternary Compounds A49Tl108+x (A=K, Rb, Cs; x=0-1.76) Related to the K49Tl108 Type Structure

V.F. Schwinghammer, M. Janesch, F. Kleemiss, S. Gärtner, Z. Anorg. Allg. Chem. 648, 1-7 (2022)  DOI: 10.1002/zaac.202200117

• The Role of Different Alkali Metals in the A15Tl27 Type Structure and the Synthesis and X-ray Structure Analysis of a New Substitutional Variant Cs14.53Tl28.4        

V.F. Schwinghammer, S.M. Tiefenthaler, S. Gärtner, Materials 14, 7512 (2021)     DOI: 10.3390/ma14247512

• Spotlight on Alkali Metals: The Structural Chemistry of Alkali Metal Thallides

S. Gärtner, Crystals 10, 1013 (2020) DOI: 10.3390/cryst10111013

•  Investigations on Tetragonally Distorted Sodium Thallide NaTl‐tI8
  S. Tiefenthaler, M. Schlosser, F. Pielnhofer, I. G. Shenderovich, A. Pfitzner, S. Gärtner, Z. Anorg. Allg. Chem. 646, 82 (2020) DOI:10.1002/zaac.201900269

• Synthesis of the Tetragonal Phase of Zintl’s NaTl and Its Structure Determination from Powder Diffraction Data
  S. Tiefenthaler, N. Korber, S. Gärtner, Materials 12, 1356 (2019) DOI:10.3390/ma12081356

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  Elusive Zintl Ions [μ HSi₄]³⁻ and [Si₅]²⁻ in Liquid Ammonia: Protonation States, Sites, and Bonding Situation by NMR and Theory
  F. Hastreiter, C. Lorenz, J. Hioe, S. Gärtner, L. Nanjundappa, N. Korber, R. M. Gschwind, Angew. Chem. 58, 3133 (2019) DOI:10.1002/anie.201812955

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  Structural Chemistry of Halide including Thallides A₈Tl₁₁X_1−n  (A = K, Rb, Cs; X = Cl, Br; n = 0.1–0.9)

  S. Gärtner, S. Tiefenthaler, N. Korber, S. Stempfhuber, B. Hischa, Crystals 8, 319 (2018) DOI:10.3390/cryst8080319

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  Single Crystal X-ray Structure Analyses of Thallides: Halide Incorporation and Mixed Alkali Sites in A₈Tl₁₁X (A = K, Rb, Cs; X = Cl, Br)

  S. Gärtner, S. Tiefenthaler, Proceedings 2, 1124 (2018) DOI:10.3390/IECC_2018-05259

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  Structure of [HSi₉]³⁻ in Solid State and Its Unexpectedly High Dynamics in Solution
  C. Lorenz, F. Hastreiter, J. Hioe, L. Nanjundappa, S. Gärtner, N. Korber, R. M. Gschwind, Angew. Chem. 130, 13138 (2018) DOI:10.1002/ange.201807080

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  Ammoniates of Zintl Phases: Similarities and Differences of Binary Phases A₄E₄ and Their Corresponding Solvates
  C. Lorenz, S. Gärtner, N. Korber, Crystals 8, 276 (2018) DOI:10.3390/cryst8070276

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  Dinuclear indium and thallium diyls: biscarbenoids or metal cluster?
  M. Desat, S. Gaertner, R. Kretschmer, Chem.Commun. 53, 1510-1513 (2017)
  DOI:10.1039/C6CC09488K

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  Si₄⁴⁻ in Solution - First Solvate Crystal Structure of the Ligand-​free Tetrasilicide Tetraanion in Rb₁.₂K₂.₈Si₄ ⋅ 7 NH₃
  C. Lorenz, S. Gaertner, N. Korber, Z. Anorg. Allg. Chem. 643, 141-145 (2017)
  DOI:10.1002/zaac.201600336

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  Selective P4 Activation by a Highly Reduced Cobaltate: Synthesis of Dicobalt Tetraphosphido Complexes
  S. Pelties, T. Maier, D. Herrmann, B. de Bruin, C.  Rebreyend, S. Gaertner, I. G. Shenderovich, R. Wolf,  Chem. Eur. J. 23, 6094-6102 (2017)
  DOI:10.1002/chem.201603296

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  Co-​crystallization of Half-​sandwich (RM,​RC)​/(SM,​RC)​-​Diastereomers in Single Crystals
  H. Brunner, T. Tsuno, M. Bodensteiner, S. Gaertner, C. Miyahara, S.  Ito, T. Kurosawa, K. Koyama, Eur. J. Inorg. Chem. 2016, 5405-5410 (2016)
  DOI:10.1002/ejic.201600962

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  The first chelate-free crystal structure of a silicide transition metal complex K₀.₂₈Rb₇.₇₂[Si₉Ni(CO)₂]₂⋅16NH₃
  S. Gärtner, M. Hamberger, N. Korber, Crystals 5, 275-282 (2015) DOI:10.3390/cryst5030275

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  Stability and Conversion of Tin Zintl Anions in Liquid Ammonia Investigated by NMR Spectroscopy
  F. Fendt, C. Koch, M. Neumeier, S. Gärtner, R. M. Gschwind, N. Korber, Chem. Eur. J. 21, 14539-14544 (2015) DOI:10.1002/chem.201501100

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  About the polymorphism of [Li(C₄H₈O)₃]I: crystal structures of trigonal and tetragonal polymorphs
  S. Gärtner, T. Gärtner, R. M. Gschwind, N. Korber, Acta Cryst. E70, 555-558 (2014) DOI:10.1107/S160053681402529X

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  Coordination preferences of the alkali cations sodium and caesium in the mixed-cationic Zintl ammoniate Cs₃.₂Na₀.₈Ge₉·5.3NH₃
  S. Gärtner, C. Suchentrunk, N. Korber, Acta Crystallogr. C70, 1036-1039 (2014) DOI:10.1107/S2053229614021998

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  Reaction of Sn₄⁴⁻ in liquid ammonia: the formation of Rb₆[(η²-Sn₄)Zn(η³-Sn₄)]·5NH₃
  F. Fendt, C. Koch, S. Gärtner, N. Korber, Dalton Trans. 42, 15548-15550 (2013) DOI:10.1039/C3DT51932E

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  Zintl Anions S. Gärtner, N. Korber, in: K. Poeppelmeier (Ed.), J. Reedijk (Ed.), Main-Group Elements, Comprehensive Inorganic Chemistry II (Second Edition) 1, Elsevier Ltd., Amsterdam Oxford Waltham (2013) S. 251-267; ISBN 978-0-08-096529-1 DOI:10.1016/B978-0-08-097774-4.00110-8

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  NMR-spektroskopische Detektion der schwer zu fassenden hochgeladenen Zintl-Ionen Si₄⁴⁻ und Sn₄⁴⁻ in flüssigem Ammoniak
  M. Neumeier, F. Fendt, S. Gärtner, C. Koch, T. Gärtner, N. Korber, R. M. Gschwind, Angew. Chem. 125, 4579-4582 (2013) DOI:10.1002/ange.201209578

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  [Rb(18-crown-6)][Rb([2.2.2]-cryptand)]Rb₂Sn₉·5NH₃
  S. Gärtner, N. Korber, Acta Crystallogr. E67, m613-m614 (2011) DOI:10.1107/S1600536811013997

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  Polyanions of group 14 and Group 15 elements in alkali and alkaline earth metal solid state compounds and solvate structures S. Gärtner, N. Korber, in: T. F. Fässler (Ed.), Zintl Ions, Structure and Bonding 140, Springer, Berlin Heidelberg (2011) S. 25-57; ISBN 978-3-642-21180-5 DOI:10.1007/430_2011_43

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  Dissolving Silicides: Syntheses and Crystal Structures of New Ammoniates Containing Si₅²⁻ and Si₉⁴⁻ Polyanions and the Role of Ammonia of Crystallisation
  S. Joseph, C. Suchentrunk, N. Korber, Z. Naturforsch. 65b, 1059-1065 (2010)

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  Chemie mit substituentenfreien Silicium-Clustern in Lösung – ein Übergangsmetallkomplex eines Polysilicid-Anions
  S. Joseph, M. Hamberger, F. Mutzbauer, O. Härtl, M. Meier, N. Korber, Angew. Chem. 121, 8926-8929 (2009) DOI:10.1002/ange.200904242

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  Si₉⁴⁻ Anions in Solution - Structures of the Solvates Rb₄Si₉·4.75NH₃ and [Rb(18-crown-6)]Rb₃Si₉⋅4NH₃, and Chemical Bonding in Si₉⁴⁻
  S. Joseph, C. Suchentrunk, F. Kraus, N. Korber, Eur. J. Inorg. Chem., 4641-4647 (2009) DOI:10.1002/ejic.200900230

22nd Conference on Inorganic Chemistry by GDCH divisions of Inorganic Chemistry (Wöhler-Vereinigung) and Solid-State Chemistry & Materials Research (Festkörperchemie und Materialforschung)

From the 16.-18th of september the 22nd Conference on Inorganic Chemistry took place at the TUM Research Center in Garching. Together with the two members of AK Korber, Paul and Michael, we joint this conference, where we met old and new friends. While Steffi held a speech on tuesday, we four PhDs presented each our poster on monday or tuesday in the evening. After three days full with interessting talks, the conference ended with the social evening in the AUGUSTINER STAMMHAUS in Munich.

Visit from AK Hoch

On 6th of august four members of the AK Hoch including Tino visited us for the exchange of samples and some new learned techniques. As a surprise also Jan Minár joined our meeting. So the bosses could chat about different topics, while we PhDs worked in the lab. In the afternoon the session was relocated to the castle in Donaustauf and to Steffi´s garden, where she and her husband provided us with food and drinks. That's how we ended the official part in the evening.

Award for Stefanie Gärtner

Steffi was one of three outstanding female academics to be honoured with the Maria Weber Grant from the Hans Böckler Foundation.

Pressemitteilung Uni Regensurg

Pressemitteilung Hans-Böckler-Stiftung

Solid State Symposium in Hirschegg

This year we were once again able to take part in the Solid State Symposium in Hirschegg from 13-15 June 2024. After we closed the symposium last year, it is only fair to open this one. With two lectures on alkali metal trielides, we brought new insights into the world of polar intermetallics. This was followed by many more exciting presentations. Friday morning was free time, which most of us used for a hike.

Visit to the LMU München

On 11 April 2024, we travelled to the Bavarian capital Munich and visited the AK Hoch at LMU Munich. After lunch together, Steffi went to the meetings with the other professors and we were both allowed to participate in a Cs2O presentation, weld silver yolks, prepare crystals in capillaries and get to know many other methods and great machines. The evening was rounded off with a presentation by Steffi, before ending with the post-session at the Gasthaus & Hotel zum ERDINGER Weißbräu.

32nd Annual Meeting of the DGK in Bayreuth

Bayreuth is just under two hours by train from Regensburg. This was the venue for the 32nd annual conference of the German Society of Crystallography (DGK) from 18-21 March 2024. In addition to four plenary lectures from different disciplines, there were also many exciting microsymposia covering topics such as structural biology, crystallography under extreme conditions, quantum crystallography, aperiodic and disordered structures and much more. Vanessa and Melissa each presented the results of their research in one of the two poster sessions, whereby Melissa was allowed to tease her poster with an additional oral poster presentation.

On the first evening, we went to the Science Slam organised by Stoe, where some presented their own research in a satirical and funny way.

The next day there were three times four Microsymposia and one Plenary Lecture. During the generously calculated lunch break, we had some time to see Bayreuth. We ended the evening at the ‘Get Together’ of the Young Crystallographers, where we met Prof Dr Florian Kleemiß (RWTH Aachen) again.

The last evening was similar to the first. First there was a social evening in the restaurant ‘Liebesbier’ with very good food.

So with plenty of coffee, we were awake and ready for the first session on the last day. The conference ended with a great talk on misarrangements and quasicrystals.

Melissa's Blog Post for the Young Crystallographers

57. Hemdsärmelkolloquium in Stuttgart

In mid-March (14-16 March 2024), Steffi, Vanessa and Michael (AK Korber) travelled to the 57th Shirtsleeve Colloquium, which took place at the Max Planck Institute for Solid State Research in Stuttgart-Vaihingen. Steffi gave a lecture there alongside many other scientists (‘It's all in the mix’). To summarise, there was good food, lots of interesting conversations, discussions and also new contacts.

(Picture 1 from MPI Team, Picture 2 from Prof. Dr. Arno Pfitzner)

Festkörperpraktikum, Forschungspraktikum und Synthec Versuche

Since December 2023, various internships have again taken place at our department and at Prof Korber's AK.

• On the one hand, we were able to supervise two groups for the 7th semester practical course on preparative methods. In addition to high-temperature solid-state syntheses in tantalum ampoules, they also carried out dissolution experiments in liquid ammonia. In addition, we also segregated potassium for purification and carried out diffraction experiments on single crystals and powders.
•  Since the beginning of February, we have also had a research intern who is supporting Melissa in the investigation of mixed indidene thallides. She is also familiarising herself with our working methods, such as solid-state syntheses, dissolution experiments and diffraction experiments.
•  As part of the synthesis techniques practical, Vanessa offers a reduction of RbCl with Ca to obtain elemental rubidium according to Hackspill.

Visit in Pilsen

We had all been looking forward to our visit to Pilsen, but Covid put a spanner in the works, at least for Steffi and Vanessa. Melissa and Jan-Malte therefore travelled to the Czech Republic alone. From 23.10.2023 to 25.10.2023, they visited the New Technologies Research Centre at the University of West Bohemia, where Prof. Dr Ján Minár's working group carried out the first XPS measurements on our alkali metal cadmium halides as part of the KKR and Wien2K workshop. This huge machine is really impressive, as in addition to XPS, ARPES measurements, a spin analysis and time-resolved photoemission can also be carried out. Melissa and Jan-Malte rounded off the fantastic visit together with the scientists from Pilsen in the LÉKÁRNA restaurant with delicious, traditional Czech food. Another trip to Pilsen is planned, and hopefully Vanessa and Steffi will be able to join them.

Front Cover for ZAAC

DOI: 10.1002/zaac.202300211

M. Janesch, V.F. Schwinghammer, I.G. Shenderovich, S. Gärtner, Z. Anorg. Allg. Chem. 2023, 649, e202300112. DOI:10.1002/zaac.202300112

KKR and Wien2K Workshop Part 1 in Regensburg

From 24-27.07.2023 we had a visit from the working group around Prof. Dr. Ján Minár from the New Technologies Research Centre of the University of West Bohemia in Pilsen. Ján Minár and his colleagues showed us new theoretical methods (KKR and Wien2K) and their equipment in the laboratory, with which we try to clarify questions about the ternary alkali metal trielides. We also showed them our working methods for solid-state production, laboratory facilities and single-crystal X-ray diffractometers in the ZA.

18th European Conference on Solid State Chemistry in Prag

The 18th European Solid State Conference ECSSC took place in an old Benedictine monastery in the west of Prague from 9-12 July 2023. In addition to exciting lectures on perovskites, battery materials, investigation methods and much more, we were also able to present our own results at one of the two poster sessions. After the informative but at the same time exhausting conference days at approx. 37°C, we were able to enjoy the golden city at night together with other conference participants.

Visit from AK Hoch 

After Steffi and Constantin Hoch (LMU) met for the first time in persona at the DGK in Frankfurt am Main in March, Tino was invited to give a lecture at the AC Colloquium. On 29 June 2023, the time had come.

As the reception committee, Steffi and Vanessa picked up the AK Hoch (Tino, Daniel, Lukas, Irina and Timo) from the train station in Regensburg. A tight programme then began for the five of them. While Tino spent most of the time talking to other professors, we visited our laboratories and demonstrated working techniques from the Korber/ Gärtner working group, such as cesium visualisation according to Hackspill, tantalum welding, condensing ammonia and searching for crystals under nitrogen cooling.

After Tino's super interesting lecture, the evening ended with the first AC summer party in the chemistry beer garden.

Solid State Symposium in Hirschegg

After around 15 years, we took part in the Solid State Symposium in Hirschegg again from 8-11 June 2023 as the Regensburg representative. It was also (presumably) the 50th anniversary, which was celebrated with a special dinner on Friday after the hike. There were a total of 34 short lectures, the last of which was given by Vanessa. The evening lecture by PD Constantin Hoch (LMU) was dedicated to the history of ammonium amalgam.

31st Annual Meeting of the DGK in Frankfurt (Main)

After a Germany-wide local and long-distance transport strike took place on Monday 27 March 2023 and the 31st annual conference of the German Crystallographic Society started in Frankfurt am Main, we spontaneously travelled by car instead of by ICE from Regensburg to Frankfurt. As a result, the conference was still somewhat sparsely attended on Monday, but this changed over the following days. After a day full of exciting talks, Tuesday ended with the first poster session, in which we presented our posters. On Wednesday, Steffi gave a talk in the Inorganic Structural Chemistry session. The day was rounded off with the Social Evening in Schuch's Restaurant. On the last day of the conference, Melissa was awarded one of three poster prizes for her poster on ‘Investigating the Role of Alkali Metals in the Structure Type K14Cd9Tl21’. She received a cash prize of €200 and a huge bouquet of flowers. In the afternoon, we visited Rigaku during a lab tour in Neu-Isenburg before travelling back to Regensurg by ICE.

Poster Melissa, Poster Vanessa, Vortrag Steffi

21st Conference on Inorganic Chemistry by GDCH divisions of Inorganic Chemistry (Wöhler-Vereinigung) and Solid-State Chemistry & Materials Research (Festkörperchemie und Materialforschung)

Together with the rest of the AK Korber, we (Melissa, Vanessa, AG Gärtner) went to Marburg from 26-28 September 2022 for the 21st Conference for Inorganic Chemistry of the GDCH departments Wöhler-Vereinigung and Solid State Chemistry and Materials Research. We (almost) all presented a poster. The conference was rounded off with a social evening at the Hotel Restaurant Dammühle.

30th Annual Meeting of DGK

The 30th Annual Meeting of the German Crystallographic Society was held as an online conference from 14-17 March 2022, after a face-to-face event in Munich was not possible due to the pandemic. Nevertheless, we were able to present a joint poster on the ternary compound Na7RbTl4. In addition, Steffi gave a talk on the alkali metal-thallide compounds in the approximate alkali metal to thallium ratio of 1:2.