Prof. Dr. Richard Dronskowski

Chair of Solid-state and Quantum Chemistry


Research

Research



In a nutshell, the Dronskowski group is specializing in the fields of synthetic and quantum-theoretical solid-state chemistry, bordering with materials science, solid-state and theoretical physics, crystallography, as well as quantum and computational chemistry. In detail, we are synthesizing novel, sometimes extremely sensitive, compounds and elucidate their compositions and crystal structures by means of X-ray and neutron diffractional techniques. The characterization of their physical properties, that is, electronic transport and magnetism, also plays a very important role.
We regularly perform solid-state quantum-chemical calculations from first principles to yield the electronic (band) structures and, in particular, to extract the important chemical bonding information needed to thoroughly understand the interplay between chemistry and physics. We have been a major player in making theoretical approaches an essential part of solid-state chemistry. Indeed, the ultimate quest for prediction and understanding is at the very center of our research; thus, syntheses are theory-driven and experiments challenge theories. Alternatively expressed, we have given up any unnecessary fencing between synthetic and theoretical approaches.
At the present moment, we expect the most exciting research opportunities in the fields of extended nitrides and oxynitrides, magnetic intermetallics, cyanamides and carbodiimides, and, also, in the quantum-chemical modeling of hypothetical phases and very large solid-state systems. In addition, there is an enormous scientific and, possibly, economical potential in (pathological) biomineralization, namely on the borderline between chemistry and medicine. For reasons of brevity, let's merely mention a small number of typical examples to illustrate our research philosophy and how it has evolved over the years:


Research: Without the slightest doubt, extended nitrides are clearly becoming the electronic (non-oxidic) materials of the 21st century, not only because of the fascinating optoelectronic properties of gallium nitride, GaN, and similar phases. There has been an enormous progress in the synthesis of more complex (ternary or quaternary) nitrides, and our group has specialized, some years ago, in the prediction of new nitride materials, yet to be made, or the characterization of existing nitrides [1]. Within the last years, we have studied, by means of first-principles total-energy calculations, the ternary system MFe3N (where M stands for another transition metal), derivatives of the famous Fe4N phase which is a magnetically as well as mechanically important material. Because of these calculations and the theoretically derived enthalpy-pressure diagrams (see right figure), we have predicted the existence of the compound RhFe3N and the high-pressure phase IrFe3N [2]. Before having synthesized the Rh-based material, we knew that this compound would behave ferromagnetically; in addition, the theory is able to correctly predict the conditions of its synthesis.


Research: Indeed, RhFe3N has been obtained a few months later by our group through a special chemical route of the coupled-reduction type (see figure). The new phase is indeed a very strong ferromagnet, and additional quantum-chemical calculations suggest the material to be semihard in magnetic nature [3]. With respect to IrFe3N, high-pressure routes will be needed to prepare the phase starting from FeN, Ir and molecular nitrogen, and we would be happy to either cooperate with high-pressure groups to eventually synthesize this exciting compound. For the future, we are planning to extend the theoretical as well as synthetic high-pressure nitride chemistry, in particular with respect to mixed transition-metal/rare-earth metal nitride systems because the 3d/4f electronic interplay in such metal-rich phases will guarantee even more exciting magnetic properties. On the theoretical side, the most recent result is the first-principles falsification of platinum nitride (PtN) which does not exist although it has been claimed by others. Instead, PtN2 adopting the pyrite structure was predicted by us, and this platinum diazenide (not nitride) has been made, independently, by other experimentalist in the meantime [4].


Research:Also, our group has specialized in the complex chemistry of novel metal oxynitrides, a very interesting class of materials; the German Science Foundation has recognized the importance of oxynitride chemistry by having started a special research initiative in which our group plays its role. For oxynitrides, the chemical tuning of the materials properties does not occur in the cationic but in the anionic substructure. Because these compounds are much more difficult to make, empirical knowledge is rare and a deep understanding based on quantum-chemical calculations may turn out extremely useful. As an example, we have cooperated in characterizing novel zirconium oxynitride films from the plasma phase [5] and we have theoretically characterized CoO0.5N0.5 (see above figure), the first oxynitride of a magnetic transition metal [6] as enthalpically unstable. This oxynitride only exists because of the existence of likewise unstable zinc blende-type CoO.


Research:Another important step [7] has been the prediction of a stoichiometrically precise vanadium oxynitride, VON, and the high-pressure conditions of its synthesis (see left figure). Also, the high-pressure phases of NbON and TaON have been predicted and wait for their discoveries. Many more synthetic and theoretical investigations are planned for the chemistry of oxynitrides, and applications are particularly obvious for the realm of, say, heterogeneous catalysis and non-toxic pigments. Note that the color of these phases (which simply reflect the topology of the band structure in the visual regime) may be nicely controlled by the stoichiometry of the anionic sub-structure.


Research:Starting in the late 1990s, our group has paved the way for a chemical understanding of itinerant (that is, delocalized) magnetism of the transition metals and their alloys. We have succeeded to re-formulate the phenomena of both itinerant ferro- and antiferromagnetism into a chemical bonding theory in which the tendency to behave either as a ferro- or antiferromagnet simply results from occupied anti- and nonbonding states (see right figure) at the Fermi level [8]. Based on these predictions, we have been the first to rationally design and prepare ferro- and antiferromagnets in the quaternary system alkaline-earth metal/rhodium/transition metal/boron, and the synthesis of the three new compounds Sc2FeRh5B2, Sc2MnRu2Rh3B2 and also Sc2FeRu3Rh2B2 [9] has corroborated our theoretical efforts. Research: Within the last two years, we have continuously made a dozen of similar intermetallic compounds (see structural sketch on the left), yet to be published, in which their valence electron concentrations are carefully adjusted between 60 and 68 electrons per formula unit, and this corresponds to a fine-tuning of the Mn/Fe electron density in fractions of an electron! This research topic has turned out extraordinarly fruitful, and we plan to heavily invest in the crystal chemistry of such novel and complex magnetic intermetallics. In general, the bonding theory of such metal-rich intermetallic phases is quite underdeveloped despite the fact that a chemical understanding is a prerequisite for truly rational syntheses. On the other side, complex intermetallic magnets are true bonanzas for the restless synthetic solid-state chemist because there are infinite possibilities in terms of structure and composition.


Research:As has been alluded to already, nitrogen-containing solids are a hot topic in contemporary solid-state chemistry, and we are also specializing in more complex phases with involve carbon-nitrogen anions such as cyanamides and carbodiimides as structure-building ingredients. In fact, the majority of all presently known solid cyanamides/carbodiimides has been made by our group. As a recent accomplishment, there is the phase HgNCN which represents the first solid state cyanamide/carbodiimide polymorphism ever encountered [10] as well as more much complex rare-earth carbodiimides such as LiEu2(NCN)I3 which are comprised of rare-earth tetrahedral clusters [11]; here, the NCN2- units serve as linkers between the magnetic europium units; clearly, there is more structural flexibility for NCN2- than for the simple N3- (nitride) ion such that even condensed and oligomeric cluster structures can be generated [12]. Also, because of the reduced anionic charge of NCN2- compared to N3-, there is more covalency present in these "2nd generation" nitrogen-based solid-state systems.


Interestingly, no cyanamide/carbodiimide phase of the magnetic transition metals has ever been reported which involves a non-d10 electron count. This is particularly puzzling because, as we suspect, a couple of groups have been trying to reach that goal. Research: In 2004, we had started a massive (almost combinatorial) computational project, funded by the von Humboldt foundation and targeted at the structure prediction of these phases, and the results indicate that all MNCN phases - before they have been made - are thermodynamically unstable with respect to the elements [13]. Given this information on hypothetical phases, the synthesis of MnNCN, the first member of a novel class of magnetic materials, is straightforward by removing another side product from the chemical equilibrium. As predicted, MnNCN (see left ORTEP sketch) is a high-spin antiferromagnetic material [14]. Other phases (such as CuNCN) can also be made [15]; we believe that there is an infinite number of ternary, quaternary or even higher magnetic carbodiimides waiting to be realized, and we have just begun to explorate this exciting kind of synthetic chemistry.


Research: A new, truly interdisciplinary direction of research is given by pathological biomineralization for which accurate analytical techniques, modern diffractional methods and, sure enough, intense medical research must be synergetically combined. Did you know that the calcification of the aortic valve of the human heart is one of the major killers in all western societies? Almost nothing is known about the cause of this "calcification" (see right figure), and even the technical term is entirely misleading because the mineral deposits are composed of Ca-deficient hydroxyapatite which is, chemically, a simple phosphate [16]. Research:We have found that - very surprisingly and counter-intuitively, too - only genetic reasons determine whether or not individuals will suffer from that disease, and we also believe that our recent crystallographic and statistical studies [17] (see left figure) will make it easier for the medical people to successfully navigate in the search for a cure for this disease. Without much doubt, there is enormous potential lurking in this hybrid of solid-state chemistry and medical research despite the fact that the experimental techniques involved, with the exception of X-ray crystallography, are relatively simple and inexpensive.


With the advent of very fast (parallel) computer architectures, density-functional theory-based molecular-dynamics simulations for molecules and solids are becoming increasingly popular, both on the pico- and nanometer length scales. For huge systems, we think that alternative parameterizations (which require a crystal-chemical understanding) may - sometimes - serve as cheaper (that is, much faster) alternatives [18]. In addition, order-N scaling electronic-structure methods using super-localized atomic orbitals are another alternative although their usefulness differs drastically from system to system. Also, entirely new approaches are needed to more systematically deal with periodic systems in which electron correlation plays a major, if not dominating, role such that density-functional theory appears as an invalid tool [19]. Upon searching for intermetallic compounds in the realm of anticorrosive alloys (binary system Sn/Zn), however, we have found a promising combination of density-functional theory on the one side and classic thermochemical approaches [20]. Here, too, the research is motivated by the paramount importance of corrosion protection; in Germany alone, corrosion destroys on the order of Euro 50 billion (!) each year; that's a lot of money. This kind of metal-oriented research will also become more important in the near future, in particular for high-performance steel-related activities.


Last, let's mention a few all-time research favorites of this group which we consider a useful supplement of a modern solid-state chemical laboratory. By pure curiosity, we have always been interested in the crystal chemistry of small high-energy molecules. As only one example, one might mention the crystal-structure determination and the study of the phase transformation of solid S4N4 in the proximity of its detonation temperature [21]. On the other side, metastable (albeit non-explosive) extended solids, for example binary indium halides such as In4Br7, have contributed to our ability to solve very complex structures from powder data and understand second-order Jahn-Teller distortions close to absolute zero temperature; such studies demand high-resolution neutron powder data [22]. Clearly, these "finger exercises" have no direct relationship with economically important materials but they provide and guarantee the skill of the coworkers to competently deal with any material. If one can handle and characterize air- and light-sensitive explosives at any temperature, the structural characterization of ionic liquids is not too difficult [23], and the characterization of oxidic ferroelectrics seems almost trivial [24]. There must always be a little room for unconventional, out-of-the-ordinary ideas.



References

[1] First-Principles Studies of Extended Nitride Materials, P. Kroll, B. Eck, R. Dronskowski, Adv. Mater. 2000, 12, 307.

[2] Predicting new ferromagnetic nitrides from electronic structure theory: IrFe3N and RhFe3N, J. von Appen, R. Dronskowski, Angew. Chem. Int. Ed. 2005, 43, 1205.

[3] Synthesis, crystal structure and magnetic properties of the semi-hard itinerant ferromagnet RhFe3N, A. Houben, P. Müller, J. von Appen, H. Lueken, R. Niewa, R. Dronskowski, Angew. Chem. Int. Ed. 2005, 44, 7212.

[4] Mysterious Platinum Nitride, J. von Appen, M.-W. Lumey, R. Dronskowski, Angew. Chem. Int. Ed. 2006, 45, 4365.

[5] Composition and formation mechanism of zirconium oxynitride films produced by reactive direct current magnetron sputtering, J. M. Ngaruiya, O. Kappertz, C. Liesch, P. Müller, R. Dronskowski, M. Wuttig, Phys. Stat. Sol. A 2004, 201, 967.

[6] Quantum-Chemical Studies on the Geometric and Electronic Structures of Bertholloide Cobalt Oxynitrides, M.-W. Lumey, R. Dronskowski, Adv. Funct. Mat. 2004, 14, 371.

[7] First-Principles Electronic Structure, Chemical Bonding and High-Pressure Phase Prediction of the Oxynitrides of Vanadium, Niobium and Tantalum, M-W. Lumey, R. Dronskowski, Z. Anorg. Allg. Chem. 2005, 631, 887.

[8] The Orbital Origins of Magnetism: From Atoms to Molecules to Ferromagnetic Alloys, G. A. Landrum, R. Dronskowski, Angew. Chem. Int. Ed. 2000, 39, 1560.

[9] Chemically Tuning between Ferromagnetism and Antiferromagnetism by Combining Theory and Synthesis in Iron/Manganese Rhodium Borides, R. Dronskowski, K. Korczak, H. Lueken, W. Jung, Angew. Chem. Int. Ed. 2002, 41, 2528.

[10] Synthesis, Structure Determination, and Quantum-Chemical Characterization of an Alternate HgNCN Polymorph, X. Liu, P. Müller, P. Kroll, R. Dronskowski, Inorg. Chem. 2002, 41, 4259.

[11] Formation of Complex Three- and One-Dimensional Interpenetrating Networks within Carbodiimide Chemistry: NCN2--Coordinated Rare-Earth-Metal Tetrahedra and Condensed Alkali-Metal Iodide Octahedra in Two Novel Lithium Europium Carbodiimide Iodides, LiEu2(NCN)I3 and LiEu4(NCN)3I3, W. Liao, C. Hu, R. K. Kremer, R. Dronskowski, Inorg. Chem. 2004, 43, 5884.

[12] Eu8(NCN)5-dI6+2d (d = 0.05): a Novel Rare-Earth Carbodiimide Iodide containing Oligomeric Tritetrahedral Eu8 Clusters, W. Liao, B. P. T. Fokwa, R. Dronskowski, Chem. Commun. 2005, 3612.

[13] A theoretical study on the existence and structures of some hypothetical first-row transition-metal M(NCN) compounds, M. Launay, R. Dronskowski, Z. Naturforsch. B 2005, 60, 701.

[14] Synthesis, Crystal Structure and Properties of MnNCN, the first Carbodiimide of a Magnetic Transition Metal, X. Liu, M. Krott, P. Müller, C. Hu, H. Lueken, R. Dronskowski, Inorg. Chem. 2004, 44, 3001.

[15] A Novel Method for Synthesizing Crystalline Copper Carbodiimide, CuNCN. Structure Determination by X-ray Rietveld Refinement, X. Liu, M. A. Wankeu, H. Lueken, R. Dronskowski, Z. Naturforsch. B 2005, 60, 593.

[16] The amount of calcium-deficient hexagonal hydroxyapatite in aortic valves is influenced by gender and associated with genetic polymorphisms in patients with severe calcific aortic stenosis, J. R. Ortlepp, F. Schmitz, V. Mevissen, S. Weiss, J. Huster, R. Dronskowski, G. Langebartels, R. Autschbach, K. Zerres, C. Weber, P. Hanrath, R. Hoffmann, Eur. Heart. J. 2004, 25, 514.

[17] Chemical analyses and X-ray diffraction investigations of human hydroxyapatite minerals from aortic valve stenoses, L. Stork, P. Müller, R. Dronskowski, J. R. Ortlepp, Z. Kristallogr. 2005, 220, 201.

[18] Atomistic Simulations of Solid-State Materials based on Crystal-Chemical Potential Concepts: Basic Ideas and Implementation; B. Eck, R. Dronskowski, J. Alloys Compd. 2002, 338, 136.

[19] A Geminal Model for the Electronic Structures of Extended Systems, A. Tokmachev, R. Dronskowski, Chem. Phys. 2006, 322, 423.

[20] A Theoretical Search for Intermetallic Compounds and Solution Phases in the Binary System Sn/Zn, J. von Appen, K. Hack, R. Dronskowski, J. Alloys Compd. 2004, 379, 110.

[21] Tetrasulphur Tetranitride: Phase Transition and Crystal Structure at Elevated Temperature, S. H. Irsen, P. Jacobs, R. Dronskowski, Z. Anorg. Allg. Chem. 2001, 627, 321.

[22] Temperature-Dependent Diffraction Studies on the Phase Evolution of Tetraindium Heptabromide, M. Scholten, P. Kölle, R. Dronskowski, J. Solid State Chem. 2003, 174, 349.

[23] Hydrogen Bonding in the Crystal Structures of the Ionic Liquid Compounds Butyldimethylimidazolium Hydrogen Sulfate, Chloride and Chloroferrate(II,III), P. Kölle, R. Dronskowski, Inorg. Chem. 2004, 43, 2803.

[24] Some A6B5O18 cation-deficient perovskites in the BaO-La2O3-TiO2-Nb2O5 system, H. Zhang, L. Fang, R. Dronskowski, P. Müller, R. Z. Yuan, J. Solid State Chem. 2004, 177, 4007.

Selected Publications


Nitrides:
Electronic Structure and Bonding in Ce (Nitride) Compounds: Trivalent versus Tetravalent Cerium, G. A. Landrum, R. Dronskowski, R. Niewa, F. J. DiSalvo, Chem. Eur. J. 1999, 5, 515.

Theoretical calculations on the structures, electronic and magnetic properties of binary 3d transition metal nitrides, B. Eck, R. Dronskowski, M. Takahashi, S. Kikkawa, J. Mater. Chem. 1999, 9, 1527.

Why is Nitrogen so Different? Structure, Bonding and Magnetic Properties of some Model Nitrides, Carbides and Phosphides, G. A. Landrum, B. Eck, R. Dronskowski, Mater. Sci. Forum 2000, 325/6, 105.

First-Principles Studies of Extended Nitride Materials, P. Kroll, B. Eck, R. Dronskowski, Adv. Mater. 2000, 12, 307.

Predicting new ferromagnetic nitrides from electronic structure theory: IrFe3N and RhFe3N, J. von Appen, R. Dronskowski Angew. Chem. Int. Ed. 2005, 43, 1205.

Mysterious Platinum Nitride, J. von Appen, M.-W. Lumey, R. Dronskowski, Angew. Chem. Int. Ed. 2006, 45, 4365.

Oxynitrides:
The Electronic Structure of Tantalum Oxynitride and the Falsification of a-TaON, M.-W. Lumey, R. Dronskowski, Z. Anorg. Allg. Chem. 2003, 629, 2173.

Composition and formation mechanism of zirconium oxynitride films produced by reactive direct current magnetron sputtering, J. M. Ngaruiya, O. Kappertz, C. Liesch, P. Müller, R. Dronskowski, M. Wuttig, Phys. Stat. Sol. A 2004, 201, 967.

Quantum-Chemical Studies on the Geometric and Electronic Structures of Bertholloide Cobalt Oxynitrides, M.-W. Lumey, R. Dronskowski, Adv. Funct. Mat. 2004, 14, 371.

First-Principles Electronic Structure, Chemical Bonding and High-Pressure Phase Prediction of the Oxynitrides of Vanadium, Niobium and Tantalum, M-W. Lumey, R. Dronskowski Z. Anorg. Allg. Chem. 2005, 631, 887.

A density-functional and molecular-dynamics study on the physical properties of yttrium-doped tantalum oxynitride, H. Wolff, H. Schilling, M. Lerch, R. Dronskowski, J. Solid State Chem. 2006, 179, 2265.

Metastable Solids:
Chemical Bonding of the Binary Indium Bromides, R. Dronskowski, Inorg. Chem. 1994, 33, 6201.

Synthesis, Structure, and Decay of In4Br7, R. Dronskowski, Angew. Chem. Int. Ed. Engl. 1995, 34, 1126.

In3Ti2Br9: Jahn Teller Unstable Indium(I) and Antiferromagnetically Coupled Titanium(III) Atoms, R. Dronskowski, Chem. Eur. J. 1995, 1, 118.

The Crystal Structure of In7Br9, R. Dronskowski, Z. Kristallogr. 1995, 210, 920.

Synthesis, Crystal Structure, Electronic Structure, and Magnetic Properties of In2ThBr6, R. Dronskowski, Inorg. Chem. 1995, 34, 4991.

InCaBr3, an electron absorbent material containing univalent indium, M. Scholten, R. Dronskowski, C. R. Acad. Sci. Paris (IIb) 1996, 322, 699.

InCrBr3: A Ternary Indium Bromide Containing Jahn-Teller Unstable Cr2+ and the Magnetic Structures of InCrBr3 and InFeBr3, M. Scholten, R. Dronskowski, H. Jacobs, Inorg. Chem. 1999, 38, 2614.

Temperature-Dependent Diffraction Studies on the Phase Evolution of Tetraindium Heptrabromide, M. Scholten, P. Kölle, R. Dronskowski, J. Solid State Chem. 2003, 174, 349.

Solid-State Carbodiimides and Cyanamides:
In2.24(NCN)3 and NaIn(NCN)2: Synthesis and Crystal Structures of New Main Group Metal Cyanamides, R. Dronskowski, Z. Naturforsch. B 1995, 50, 1245.

Crystal Structure Refinement of Lead Cyanamide and the Stiffness of the Cyanamide Anion, X. Liu, A. Decker, D. Schmitz, R. Dronskowski, Z. Anorg. Allg. Chem. 2000, 626, 103.

Synthesis, Structure Determination, and Quantum-Chemical Characterization of an Alternate HgNCN Polymorph, X. Liu, P. MÜller, P. Kroll, R. Dronskowski, Inorg. Chem. 2002, 41, 4259.

Mercury Cyanamide/Carbodiimide Networks: Synthesis and Crystal Structures of Hg2(NCN)Cl2 and Hg3(NCN)2Cl2, X. Liu, R. Dronskowski, Z. Naturforsch. B 2002, 57, 1108.

Experimental and Quantum-Chemical Studies on the Thermochemical Stabilities of Mercury Carbodiimide and Mercury Cyanamide, X. Liu, P. Müller, P. Kroll, R. Dronskowski, W. Wilsmann, R. Conradt, ChemPhysChem 2003, 4, 725.

Formation of Complex Three- and One-Dimensional Interpenetrating Networks within Carbodiimide Chemistry: NCN2--Coordinated Rare-Earth-Metal Tetrahedra and Condensed Alkali-Metal Iodide Octahedra in Two Novel Lithium Europium Carbodiimide Iodides, LiEu2(NCN)I3 and LiEu4(NCN)3I3, W. Liao, C. Hu, R. K. Kremer, R. Dronskowski, Inorg. Chem. 2004, 43, 5884.

LiSr2(NCN)I3: the first empty tetrahedral strontium(II) entity coordinated by carbodiimide units but without strontium-strontium bonding, W. Liao, J. von Appen, R. Dronskowski, Chem. Commun. 2004, 2302.

Carbodiimides with Extended Structures by an Azide-Cyanide Route: Synthesis and Crystal Structure of M2Cl2NCN (M = Eu and Sr), W. Liao, R. Dronskowski, Z. Anorg. Allg. Chem. 2005, 631, 496.

Synthesis and crystal structure of ammine copper(I) cyanamide, Cu4(NCN)2NH3, X. Liu, P. Müller, R. Dronskowski Z. Anorg. Allg. Chem. 2005, 631, 1071.

A theoretical study on the existence and structures of some hypothetical first-row transition-metal M(NCN) compounds, M. Launay, R. Dronskowski, Z. Naturforsch. B 2005, 60, 701.

Synthesis, Crystal Structure and Properties of MnNCN, the first Carbodiimide of a Magnetic Transition Metal, X. Liu, M. Krott, P. Müller, C. Hu, H. Lueken, R. Dronskowski, Inorg. Chem. 2005, 44, 3001.

A Novel Method for Synthesizing Crystalline Copper Carbodiimide, CuNCN. Structure Determination by X-ray Rietveld Refinement, X. Liu, M. A. Wankeu, H. Lueken, R. Dronskowski, Z. Naturforsch. B 2005, 60, 593.

Intermetallic Compounds:
Synthesis, Crystal Structure, Electronic Structure, and Properties of Hf2In5, a Metallic Hafnide with One-Dimensional Hf-Hf and Two-Dimensional In-In Bonding, R. Pöttgen, R. Dronskowski, Chem. Eur. J. 1996, 2, 800.

Structure and Properties of Zr2Ni2In and Zr2Ni2Sn, R. Pöttgen, R. Dronskowski, J. Solid State Chem. 1997, 128, 289.

Structure, Chemical Bonding, Magnetic Susceptibility, and 155Gd Mößbauer Spectroscopy of the Antiferromagnets GdAgGe, GdAuGe, GdAu0.44(1)In1.56(1), and GdAuIn, R. Pöttgen, G. Kotzyba, E. A. Görlich, K. Latka, R. Dronskowski, J. Solid State Chem. 1998, 141, 352.

Synthesis, Structure, Chemical Bonding, and Properties of CaTIn2 (T = Pd, Pt, Au), R.-D. Hoffmann, R. Pöttgen, G. A. Landrum, R. Dronskowski, B. Künnen, G. Kotzyba, Z. Anorg. Allg. Chem. 1999, 625, 789.

Structure, Chemical Bonding, and Properties of ZrIn2, IrIn2, and Ti3Rh2In3, M. F. Zumdick, G. A. Landrum, R. Dronskowski, R.-D. Hoffmann, R. Pöttgen, J. Solid State Chem. 2000, 150, 19.

Metallic Behavior of the Zintl Phase EuGe2: Combined Structural Studies, Property Measurements and Electronic Structure Calculations, S. Bobev, E. D. Bauer, J. D. Thompson, J. L. Sarrao, G. J. Miller, B. Eck, R. Dronskowski, J. Solid State Chem. 2004, 177, 3545.

Synthesis, Structure and Properties of the New Rare-Earth Zintl Phase Yb11GaSb9, S. Bobev, V. Fritsch, J. D. Thompson, J. L. Sarrao, B. Eck, R. Dronskowski, S. M. Kauzlarich, J. Solid State Chem. 2005, 178, 1071.

Synthesis, crystal-structure determination and Fe/Rh site preference in the new ternary boride FeRh6B3, B. P. T. Fokwa, R. Dronskowski, Z. Anorg. Allg. Chem. 2005, 631, 2478.

Unusual Mn-Mn Spin Coupling in the Polar Intermetallic Compounds CaMn2Sb2 and SrMn2Sb2, S. Bobev, J. Merz, A. Lima, V. Fritsch, J. D. Thompson, J. L. Sarrao, M. Gillessen, R. Dronskowski, Inorg. Chem. 2006, 45, 4047.

Metal-Rich Cluster Compounds:
PbMo5O8 and Tl0.8Sn0.6Mo7O11, Novel Clusters of Molybdenum and Thallium, R. Dronskowski, A. Simon, Angew. Chem. Int. Ed. Engl. 1989, 28, 758.

Synthesis and Crystal Structure of PbMo5O8, a Reduced Oxomolybdate with Mo10O28 Double Octahedra, R. Dronskowski, A. Simon, W. Mertin, Z. Anorg. Allg. Chem. 1991, 602, 49.

Synthesis and Crystal Structure of Tl0.8Sn0.6Mo7O11. Mo14O34 Clusters Containing Three Condensed Mo6 Octahedra, R. Dronskowski, A. Simon, Acta Chem. Scand. 1991, 45, 850.

On the Crystal Structure of In3Mo11O17 and the Physical Properties of Oligomeric Oxomolybdates, R. Dronskowski, Hj. Mattausch, A. Simon, Z. Anorg. Allg. Chem. 1993, 619, 1397.

Superconductivity in Intercalated and Substituted Y2Br2C2, M. Bäcker, A. Simon, Hj. Mattausch, R. Dronskowski, J. Rouxel, Angew. Chem. Int. Ed. Engl. 1996, 35, 752.

La9Br5(CBC)3: A New Superconductor, Hj. Mattausch, A. Simon, C. Felser, R. Dronskowski, Angew. Chem. Int. Ed. Engl. 1996, 35, 1685.

Quantum Chemistry of the Reactivity of Solids:
Theoretical Increments and Indices for Reactivity, Acidity, and Basicity within Solid-State Materials, R. Dronskowski, J. Am. Chem. Soc. 1992, 114, 7230.

Bond Reactivities, Acidities, and Basicities within AMo3X3 Phases (A = Li, Na, K, In; X = Se, Te), R. Dronskowski, R. Hoffmann, Inorg. Chem. 1992, 31, 3107.

A Theoretical Way of Aiding the Design of Solid-State Syntheses, R. Dronskowski, R. Hoffmann, Adv. Mater. 1992, 4, 514.

Reactivity and Acidity of Li in LiAlO2 phases, R. Dronskowski, Inorg. Chem. 1993, 32, 1.

Quantum Chemistry of Itinerant Ferro- and Antiferromagnetism:
Ferromagnetism in Transition Metals: A Chemical Bonding Approach, G. A. Landrum, R. Dronskowski, Angew. Chem. Int. Ed. 1999, 38, 1389.

The Orbital Origins of Magnetism: From Atoms to Molecules to Ferromagnetic Alloys, G. A. Landrum, R. Dronskowski, Angew. Chem. Int. Ed. 2000, 39, 1560.

Itinerant Ferromagnetism and Antiferromagnetism from a Chemical Bonding Perspective, R. Dronskowski, Adv. Solid State Phys. 2002, 42, 433.

Chemically Tuning between Ferromagnetism and Antiferromagnetism by Combining Theory and Synthesis in Iron/Manganese Rhodium Borides, R. Dronskowski, K. Korczak, H. Lueken, W. Jung, Angew. Chem. Int. Ed. 2002, 41, 2528.

Electronic Structure, Chemical Bonding, and Spin Polarization in Ferromagnetic MnAl, Y. Kurtulus, R. Dronskowski, J. Solid State Chem. 2003, 176, 390.

Electronic structure and magnetic exchange coupling in ferromagnetic full Heusler alloys, Y. Kurtulus, R. Dronskowski, G. D. Samolyuk, V. P. Antropov, Phys. Rev. B 2005, 71, 14425-1.

Electronic Structure, Chemical Bonding and Finite-Temperature Magnetic Properties of full Heusler Alloys, Y. Kurtulus, M. Gillessen, R. Dronskowski, J. Comput. Chem. 2006, 27, 90.

General Quantum Chemistry of the Solid State:
Crystal Orbital Hamilton Populations (COHP). Energy-Resolved Visualization of Chemical Bonding in Solids Based on Density-Functional Calculations, R. Dronskowski, P. E. Blöchl, J. Phys. Chem. 1993, 97, 8617.

Structural and Electronic Peierls Distortions in the Elements (A): The Crystal Structure of Tellurium, A. Decker, G. A. Landrum, R. Dronskowski, Z. Anorg. Allg. Chem. 2002, 628, 295.

Structural and Electronic Peierls Distortions in the Elements (B): The Antiferromagnetism of Chromium, A. Decker, G. A. Landrum, R. Dronskowski, Z. Anorg. Allg. Chem. 2002, 628, 303.

A Theoretical Search for Intermetallic Compounds and Solution Phases in the Binary System Sn/Zn, J. von Appen, K. Hack, R. Dronskowski, J. Alloys Compd. 2004, 379, 110.

Group Functions for the Analysis of the Electronic Structures of Polymers, A. Tokmachev, R. Dronskowski, Phys. Rev. B 2005, 71, 195202.

A Geminal Model for the Electronic Structures of Extended Systems, A. Tokmachev, R. Dronskowski, Chem. Phys. 2006, 322, 423.

Pathological Biomineralization:
Relation of aortic valve calcification with cardiovascular risk factors and anti inflammatory gene polymorphism in patients with degenerative calcific aortic stenosis, J. R. Ortlepp, F. Schmitz, V. Mevissen, S. Weiss, R. Dronskowski, K. Zerres, C. Weber, R. Autschbach, B. Messmer, P. Hanrath, R. Hoffmann, J. Am. Coll. Cardiol. 2003, 41, 507A.

The amount of calcium-deficient hexagonal hydroxyapatite in aortic valves is influenced by gender and associated with genetic polymorphisms in patients with severe calcific aortic stenosis, J. R. Ortlepp, F. Schmitz, V. Mevissen, S. Weiss, J. Huster, R. Dronskowski, G. Langebartels, R. Autschbach, K. Zerres, C. Weber, P. Hanrath, R. Hoffmann, Eur. Heart. J. 2004, 25, 514.

Chemical analyses and X-ray diffraction investigations of human hydroxyapatite minerals from aortic valve stenoses, L. Stork, P. Müller, R. Dronskowski, J. R. Ortlepp, Z. Kristallogr. 2005, 220, 201.

Crystallography of Ionic Liquids:
Synthesis, Crystal Structures and Electrical Conductivities of the Ionic Liquid Compounds Butyldimethylimidazolium Tetrafluoroborate, Hexafluorophosphate and Hexafluoroantimonate, P. Kölle, R. Dronskowski, Eur. J. Inorg. Chem. 2004, 2313 & 2989.

Hydrogen Bonding in the Crystal Structures of the Ionic Liquid Compounds Butyldimethylimidazolium Hydrogen Sulfate, Chloride and Chloroferrate(II,III), P. Kölle, R. Dronskowski, Inorg. Chem. 2004, 43, 2803.

Electronic Materials:
Preparation, structure and dielectric properties of Ba4LaMNb3O15 (M = Ti, Sn) ceramics, L. Fang, H. Zhang, T. H. Huang, R. Z. Yuan, R. Dronskowski, Mater. Res. Bull. 2004, 39, 1649.

Preparation, characterization and dielectric properties of Ba3M0.33Ta4.67O15 (M = Zn, Ni) ceramics, H. Zhang, L. Fang, T. H. Huang, R. Z. Yuan, R. Dronskowski, J. Mater. Sci.: Mater. Electron. 2004, 15, 695.

Characterization and dielectric properties of Sr4La2Ti4M6O30 (M = Nb, Ta) ceramics, L. Fang, H. Zhang, R. Z. Yuan, R. Dronskowski, J. Mater. Sci.: Mater. Electron. 2004, 15, 699.

Preparation and characterization of two new dielectric ceramics Ba4NdTiNb3O15 and Ba3Nd2Ti2Nb2O15, L. Fang, C. L. Diao, H. Zhang, R. Z. Yuan, R. Dronskowski, H. X. Liu, J. Mater. Sci.: Mater. Electron. 2004, 15, 803.

Some A6B5O18 cation-deficient perovskites in the BaO - La2O3 - TiO2 - Nb2O5 system, H. Zhang, L. Fang, R. Dronskowski, P. MÜller, R. Z. Yuan, J. Solid State Chem. 2004, 177, 4007.

Synthesis, characterization and dielectric properties of a new cation-deficient perovskite Ba4La2Ti3Nb2O18, L. Fang, H. Zhang, R. Z. Yuan, R. Dronskowski, J. Mater. Sci. 2004, 39, 7093.

Preparation and Characterization of New Dielectric Ceramics Ba5LnTi2Nb3O18 (Ln = La, Nd), L. Fang, H. Zhang, L. Chen, R. Z. Yuan, R. Dronskowski, J. Mater. Sci.: Mater. Electron. 2005, 16, 43.

Powder Diffraction of Coordination Solids:
Alkali-Metal Compounds of Hydroquinone: Synthesis and Crystal Structure, U. Couhorn, R. Dronskowski, Z. Anorg. Allg. Chem. 2003, 629, 647.

Alkali-Metal ortho-Hydroxyphenolates: Syntheses and Crystal Structures from Powder X-Ray Diffraction, U. Couhorn, R. Dronskowski, Z. Anorg. Allg. Chem. 2003, 629, 2554.

Alkali-Metal meta-Hydroxyphenolates: Syntheses and Crystal Structures from Powder X-Ray Diffraction, U. Couhorn, R. Dronskowski, Z. Anorg. Allg. Chem. 2004, 630, 427.

Simulation of Very Large (Nano) Systems:
Chemical Reactions within Fe/AlN Layered Nanocomposites: A Simulation Study based on Crystal-Chemical Atomic Dynamics, R. Dronskowski, B. Eck, S. Kikkawa, Jpn. J. Appl. Phys. 2000, 39, 3326.

Atomistic simulations of solid-state materials based on crystal-chemical potential concepts: basic ideas and implementation, B. Eck, R. Dronskowski, J. Alloys Compd. 2002, 338, 136.

Atomistic simulations of solid-state materials based on crystal-chemical potential concepts: applications for compounds, metals, alloys, and chemical reactions, B. Eck, Y. Kurtulus, W. Offermanns, R. Dronskowski, J. Alloys Compd. 2002, 338, 142.

Crystal Chemistry of Energy-Rich Molecules:
The Crystal Structure of Mn2O7, A. Simon, R. Dronskowski, B. Krebs, B. Hettich, Angew. Chem. Int. Ed. Engl. 1987, 26, 139.

The Crystal and Molecular Structure of Manganese(VII) Oxide, R. Dronskowski, B. Krebs, A. Simon, G. Miller, B. Hettich, Z. Anorg. Allg. Chem. 1988, 558, 7.

Tetrasulphur Tetranitride: Phase Transition and Crystal Structure at Elevated Temperature, S. H. Irsen, P. Jacobs, R. Dronskowski, Z. Anorg. Allg. Chem. 2001, 627, 321.

Synthesis and X-Ray Crystal Structure Determination of Thiotrithiazyl Iododichloride, S4N3Cl2, S. H. Irsen, R. Dronskowski, Z. Naturforsch. B 2002, 57, 1387.

Miscellaneous:
Copper Extraction from TlCu3S2 A Neutron Diffraction and Electronic Structure Calculation Study, R. Berger, R. Dronskowski, L. Norén, J. Solid State Chem. 1994, 112, 120.

The Little Maghemite Story: A Classic Functional Material, R. Dronskowski, Adv. Funct. Mater. 2001, 11, 27.

Magnetic and electronic structure of TlCo2S2, S. Ronneteg, M.-W. Lumey, R. Dronskowski, U. Gelius, R. Berger, S. Felton, P. Nordblad, J. Solid State Chem. 2004, 177, 2977.

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