Anorganische Chemie - Beckhaus

Journale

2017

84. M. Fischer, M. Schmidtmann und R. Beckhaus
Crystal structure of the formal 20 electron zirconocene pentafulvene complex Cp2
Zr(h5:h1-adamantylidenepentafulvene): toluene:n-hexane = 1 : 0.125 : 0.125
Acta Crystallographica Section E-Crystallographic Communications E73, 2017, 1823 -1826.

 

83. M. Fischer, M. Schmidtmann und R. Beckhaus
From Five to Five - Titanium Ketimine Complexes with Monoaza-butadiene η4-Coordination Mode and Hidden η2-Imine Reactivity
Organometallics 36, 2017, DOI: 10.1021/acs.organomet.7b00673


Illustration: Friederike Kirschner

 

82. M. Manßen, C. Kahrs, I. Töben, J.-H. Bölte, M. Schmidtmann und R. Beckhaus
From Five to Seven - Ring Expansion of Monoazadiene Titanium Complexes by Insertion of Aldehydes, Ketones and Nitriles

Chemistry - A European Journal 2017, 10.1002/chem.201703873.

 

81. T. Oswald, T. Gelert, Ch. Lasar, M. Schmidtmann, T. Klüner und R. Beckhaus
Formation of Binuclear Zigzag Hexapentaene T
itanium Complexes via a Titanabutatriene [Ti=C=C=CH2] Intermediate
Angew. Chem. 129, 2017, 12465 - 12469; Angew. Chem. Int. Ed. 56, 2017, 12297 - 12301.

 

 

80. M. Manßen, I. Töben, C. Kahrs, J.-H. Bölte, M. Schmidtmann und R. Beckhaus
Reactions of Secondary Allyl Amines with Bis(
η5:η1-pentafulvene)titanium complexes: Formation of Monoazabutadiene Titanium Complexes by N-H and C-H Bond Activation
Organometallics 36, 2017, 2973 - 2981.

79. F. Jaroschik, M. Penkhues, B. Bahlmann, M. Fischer, E. Nicolas, F. Massicot, A. Martinez, D. Harakat, M. Schmidtmann, K. V. Radhakrishnan, J.-L. Vasse und R. Beckhaus
Synthesis, Characterization and Reactivity of Formal 20 Electron Zirconocene-Pentafulvene Complexes
Organometallics 36, 2017, 2004 - 2013.

78. T. Oswald, T. Beermann, W. Saak und R. Beckhaus
Crystal structure of a P4-bridged (η5-pentamethylcyclopentadienyl) (η5-adamantylcyclopentadienyl)titanium(III)complex, C50H66P4Ti2
Z. Kristallogr. - New Cryst. Struct. 232, 2017, 143 - 145.

77. M. Manßen, N. Lauterbach, T. Woriescheck, M. Schmidtmann und R. Beckhaus
Reactions of Secondary Amines with Bis(h5:h1-pentafulvene)titanium  Complexes: Formation of Titanium Amides and Titanaaziridines
Organometallics 36, 2017, 867 - 876.

76. C. Adler, M. Schmidtmann und R. Beckhaus
Crystal structure of n-butyltris(dicyclohexylamido)hafnium, C40H75N3Hf
Z. Kristallogr. - New Cryst. Struct. 232, 2017, 623 - 625.

 

75. F. Loose, M. Schmidtmann und R. Beckhaus
Imines in the Titanium Coordination Sphere - Transformation of Imidoyl Chlorides to Nitrilium Ions
Z. Anorg. Allg. Chem. 643, 2017, 443 - 446.

74. M. Manßen, M. Schmidtmann und R. Beckhaus
Crystal structure of 1,1-bis(η5-adamantylcyclopentadienyl)-3-phenyl- 2-trimethylsilyl-2,3-dihydroisotitanazole, C42H55NSiTi
Z. Kristallogr. - New Crys. Struct. 232, 2017, Nr. 4, 671 - 673.

73. T. Oswald, M. Diekmann, A. Frey, M. Schmidtmann und R. Beckhaus
Crystal structures of titanium-aluminum and -gallium complexes bearing two µ-CH3 units
Acta Crystallographica Section E-Crystallographic Communications E73, 2017, 691 - 693.

 

72. C. Adler, M. Diekmann, M. Schmidtmann und R. Beckhaus
Activation of Molecular Hydrogen by Bis(h5,h1-pentafulvene)-titanium Complexes - Efficient Formation of Titanium(III)hydrides
Z. Anorg. Allg. Chem. 643, 2017, 732 - 735.

Illustration: Friederike Kirschner

2016

71. F. Loose, M. Schmidtmann, W. Saak, R. Beckhaus,
Imines in the Titanium Coordination Sphere: h1-Imine Complexes as Sources of Azavinylidenes and Four-Membered Imine–Amido-N,N' Chelates
E. J. Inorg. Chem., 2016, Nr. 33, 5242 - 5249.

70. O. N. Frey, T. Stalling, F. Schlüter, W. Saak, M. Schmidtmann, D. Haase, R. Beckhaus
Remarkably Stability of Tetrabenzo[a,c,g,i]fluorenyl Ammonium Salts in Water: Syntheses, Reactions, and Crystal Structures
Dalton Trans. 45, 2016, 1085 - 1092.

69. T. Oswald, A. Frey, M. Schmidtmann, R. Beckhaus
Crystal structure of an isomeric bis[(η5:η1-6,6-dip-tolylpentafulvene)(η5-pentamethylcyclopentadienyl)titanium(III)]-μ2,η1:η1-dinitrogen
complex, C60H66N2Ti2

Z. Kristallogr. - New Cryst. Struct., 231, 2016, Nr. 4, 1095 - 1097.

68.  C. Adler, N. Frerichs, M. Schmidtmann, R. Beckhaus
Zwitterionic d0 Metal Complexes [(Cy2N)3M]+[(m-CH3-B(C6F5)]- (M: Ti, Zr, Hf) derived from Tris(dicyclohexylamido)methylmetal Precursors
Organometallics 35, 2016, Nr. 21, 3728 - 3733.

 

Illustration: Friederike Kirschner

67. T. Oswald, M. Schmidtmann, R. Beckhaus
Crystal structure of (η5-pentamethylcyclopentadienyl)titanium(III)dichloride (THF), C14H23Cl2OTi
Z. Kristallogr. - New Cryst. Struct., 231, 2016, (2), 637 - 639.

66. M. Manßen, C. Adler, R. Beckhaus
Flexible Structural Features of Pentafulvene Titanium Derivatives: Isolation and Characterization of NHC Complexes
Chem. Eur. J., 64, 2016, (13), 4405 - 4407.

2015

65. M. Manßen, N. Lauterbach, J. Dörfler, M. Schmidtmann, W. Saak, S. Doye, R. Beckhaus
Effizienter Zugang zu Titanaaziridinen durch C-H Aktivierung von N-Methylanilinen / Efficient Access to Titanaaziridines via C-H Activitation of N-Methylanilines at Ambient Temperature
Angew. Chem., 127, 2015, (14), 4458 - 4462; Angew. Chem. Int. Ed., 54, 2015, (14), 4383 - 4387.

64. C. Wolff, A. Gottschlich, J. England, K. Wieghardt, W. Saak, D. Haase, R. Beckhaus
Molecular and Electronic Structures of Organometallic Mono- and Dinuclear Titanium Complexes Containing π-Radical Anions of 2,2'-bipyridine and 1,10-phenanthroline. An Experimental and DFT Computational Study
Inorg. Chem., 64, 2015, (10), 4811 - 4820.

63. F. Loose, M.Schmidtmann, W. Saak R. Beckhaus
Imines in the titanium coordination sphere - Highly reactive titanaaziridines and larger titanacycles formed by subsequent C-C coupling reactions
Eur. J. Inorg. Chem., 2015, 5171 - 5187.

62. O. N. Frey, T. Stalling, F. Schlüter, W. Saak, M. Schmidtmann, D. Haase, R. Beckhaus Remarkably Stability of Tetrabenzo[a,c,g,i]fluorenyl Ammonium Salts in Water: Syntheses, Reactions, and Crystal Structures
Dalton Trans., 2015, 1085 - 1092.

2014

61. F. Loose, I. Plettenberg, D. Haase, W. Saak, M. Schmidtmann, A. Schäfer, T. Müller, R. Beckhaus
Aromatic Imines in the Titanocene Coordination Sphere—Titanaaziridine vs 1-Aza-2-titanacyclopent-4-ene Structures
Organometallics 2014, 33, 6785 - 6795.

60. C. Adler, G. Tomaschun, M. Schmidtmann, R. Beckhaus
Remarkably Robust Mono-n-butyl Group IV Dicyclohexylamido Complexes {(Cy)2N}3M(n-butyl) (Cy: cyclohexyl [C6H11], M: Ti, Zr)
Organometallics 2014, 33, 7011 - 7014.

59. H. Ebert, V. Timmermann, T. Oswald, W. Saak, M. Schmidtmann, M. Friedemann, D. Haase, R. Beckhaus
Synthesis and Reactivity of Bis(η51-pentafulvene)zirconium Complexes
Organometallics,
2014, 33, 1440 - 1452.

58. C. Adler, A. Bekurdts, D. Haase, W. Saak, M. Schmidtmann, R. Beckhaus
Bulky Titanium Amides: C–H Bond Activation under Mild Conditions
Eur. J. Inorg. Chem. 2014, 1289 - 1302; Eur. J. Inorg. Chem. 2014, 8, 1262.

 

2013

57. C. Maibohm. M. Rastedt, F. Kutscher, O. N. Frey, R. Beckhaus, K. Al-Shamery und H.-G. Rubahn

Optical waveguiding and temperature dependent photoluminescence of nanotubulars grown from molecular building blocks
Chem. Phys. Lett. 590, 2013, 98 - 91.

2011

56. J. Luo, J. Hu, W. Saak, R. Beckhaus, G. Wittstock, I. F. J. Vankelecom, C. Agert und O. Conrad
Protic ionic liquid and ionic melts prepared from methanesulfonic acid and 1H-1,2,4-triazole as high temperature PEMFC electrolytes
J. Mater. Chem. 21, 2011, 10426 - 10436.

2010

55. T. Janssen, R. Severin, M. Diekmann, M. Friedemann, D. Haase, W. Saak, S. Doye und R. Beckhaus
Bis(h5:h1-pentafulvene)titanium Complexes: Catalysts for Intramolecular Alkene Hydroamination and Reagents for Selective Reactions with N-H-acidic Substrates

Organometallics 29, 2010, Nr. 7 1806 - 1817.

54. M. Jordan, W. Saak, D. Haase und R. Beckhaus
Bridging Azines in the Coordination Sphere of Low Valent Vanadocene Derivatives
Organometallics 29, 2010, Nr. 22 5859 - 5870.

53. L. Scheffel, R. Beckhaus und I. Parchmann
Welche Inhalte gehören zum schulischen Basiskonzept Struktur-Eigenschaftsbeziehungen?
Naturwissenschaften im Unterricht Chemie, 2010, 1 - 8.

2009

52. A. Scherer, D. Haase, W. Saak, R. Beckhaus, A. Meetsma und M. W. Bouwkamp
Low-valent Pentafulvene Titanium Dinitrogen Complexes as a Precursor for Cationic Titanium Complexes
Organometallics 28, 2009, Nr. 24 6969 - 6974.

51. O. Theilmann, W. Saak, D. Haase und R. Beckhaus
Reactions of Low Valent Titanocene(II) Fragments with trans-4,4`-Azobispyridine (RN=NR, R: C5H4N): Formation of Tetranuclear Molecular Squares by trans-cis Isomerization
Organometallics 28, 2009, 2799 - 2807.

50. T. Jung, R. Beckhaus, T. Klüner, S. Höfener und W. Klopper
Unexpected Trimerization of Pyrazine in the Coordination Sphere of Low-Valent Titanocene Fragments
Journal of Chemical Theory and Computation 5, 2009, Nr. 8 2044 - 2049.

49. I. Prochnow, R. Kubiak, O. N. Frey, R. Beckhaus und S. Doye
Tetrabenzyltitanium: An Improved Catalyst for the Activation of sp3 C H Bonds Adjacent to Nitrogen Atoms
ChemCatChem 1, 2009; 162 - 172.

2008

48. J. Krahmer, R. Beckhaus, W. Saak, D. Haase
Chelating Complexes of Diethylzinc and ZnCl2 with 2,2-Bipyridine and 1,6,7,12,13,18-Hexaazatrinaphthylene (HATN) as Ligands
Z. Anorg. Allgem. Chem., 2008, 634 (10), 1696 - 1702.

47. K. Schröder, D. Haase, W. Saak, W. P. Kretschmer, A. Lützen, R. Beckhaus
Tetrabenzo[a,c,g,i]titanium(III) and -(IV) Complexes: Syntheses, Reactions and Catalytic Application
Organometallics,
2008, 27 (8), 1859 - 1868.

2006

44. R. Koch, E. Bölter, J. Stroot, R. Beckhaus
Theoretical Studies on Titanium Pentafulvene Complexes
J. Organomet. Chem., 2006, 691, 4539 - 4544. 

43. K. Schröder, D. Haase, W. Saak, A. Lützen, R. Beckhaus
Tetrabenzo[a,c,g,i]fluorenyllithium and η5-Tetrabenzo[a,c,g,i]fluorenyltitanium Complexes
Organometallics
,
2006, 25 (16), 3824 - 3836.

42. M. Diekmann, G. Bockstiegel, A. Lützen, M. Friedemann, D. Haase, W. Saak, R. Beckhaus, D. Haase, W. Saak
Chiral Bis(η51-Pentafulvene) Titanium Complexes
Organometallics, 2006, 25 (2), 339 - 348. 

40. F. Studt, N. Lehnert, B. E. Wiesler, A. Scherer, R. Beckhaus, F. Tuczek
Spectroscopic Comparison of Dinuclear Ti+ and Ti2+ μ11 Dinitrogen Complexes with Cp*/Pentafulvene and Amine/Amide Ligation: Moderate versus High Activation of N2
Eur. J. Inorg. Chem., 2006, 2, 291 - 297. 

2005

40. I. M. Piglosiewicz, R. Beckhaus, D. Haase, W. Saak
Dehydroaromatization of Quinoxalines: One-Step Syntheses of Trinuclear 1,6,7,12,13,18-Hexaazatrinaphthylene Titanium Complexes
J. Am. Chem. Soc., 2005, 127(41), 14190 - 14191. 

39. A. Scherer, K. Kollak, A. Luetzen, M. Friedemann, D. Haase, W. Saak, R. Beckhaus
Low-Valent Titanium-Pentafulvene Complexes - Formation of Dinuclear Titanium-Nitrogen Complexes
Eur. J. Inorg. Chem., 2005, 6, 1003 - 1010.

38. I. M. Piglosiewicz, S. Kraft, R. Beckhaus, D. Haase, W. Saak
Selective C-H and C-F Bond Activation Reactions of Pyridine and Fluoropyridines - Formation of Binuclear μ-X Titanocene Complexes (X = H, F) with α-Functionalized N-Heterocycles
Eur. J. Inorg. Chem., 2005, 5, 938 - 945.

37. S. Kraft, E. Hanuschek, R. Beckhaus, D. Haase, W. Saak
Titanium-Based Molecular Squares and Rectangles: Syntheses by Self-Assembly Reactions of Titanocene Fragments and Aromatic N-Heterocycles
Chem. Eur. J
., 2005, 3, 969 - 978.

2004

36. S. Kraft, R. Beckhaus, D. Haase, W. Saak
Directed Reduction of Six-Membered Nitrogen Heterocycles - Selective Formation of Polynuclear Titanium Complexes
Angew. Chem., 2004, 116, 1609 - 1614; Angew. Chem. Int. Ed., 2004, 12, 1583 - 1587. 

2002

35. J. Stroot, A. Lützen, M. Friedemann, W. Saak, R. Beckhaus
Pentafulvene Complexes of Titanium - Synthesis, Structure, and Fluxional Behavior of Cp´Ti{η6 -C5H4=C(p-Tol)2}Cl (Cp´ = Cp*, Cp)
Z. anorg. allg. Chem., 2002, 628, 797 - 802.

34. J. Stroot, D. Haase, W. Saak, R. Beckhaus
Reactions of Pentafulvene Complexes of Titanium with Nitriles and Iso-Nitriles - Synthesis and Isomerizations of σ, π-Chelate Complexes with Cp ~ N-Ligands
Z. anorg. allg. Chem., 2002, 628, 755 - 761.

33. J. Stroot, D. Haase, W. Saak, R. Beckhaus
Crystal Structure of (η5 -Pentamethylcyclopentadienyl)(η5 -1-(2,2-dimethylpropyl) cyclopentadienyl)titaniumdichloride, C20H30Cl2Ti
Z. Kristallogr. NCS, 2002, 217, 49 - 50.

32. J. Stroot, D. Haase, W. Saak, R. Beckhaus
Crystal Structure of (η5 -Pentamethylcyclopentadienyl)(η5 -1-(2,2-dimethylpropyl) cyclopentadienyl)(hydroxy)-titaniumchloride C20H31ClOTi
Z. Kristallogr. NCS, 2002, 217, 47 - 48.

2001

31. C. Santamaria, R. Beckhaus, D. Haase, R. Koch, W. Saak, I. Strauss
Reactions of the Titanaallene Intermediate [Cp*2Ti=C=CH2] with Isonitriles: An Approach to the Chemistry of Radialene Type Molecules
Organometallics, 2001, 7, 1354 - 1359.

30. R. Beckhaus, C. Santamaria
Carbene Complexes of Titanium Group Metals - Formation and Reactivity
J. Organomet. Chem., 2001, 617 - 618, 81 - 97.

1998

29. R. Beckhaus
Reaktivitätsprinzipien von Metallocenderivaten früher Übergangmetalle
Nachrichten aus Chemie, Technik und Laboratorium
, 1998, 46, 611 - 623.

28. N. Peulecke,  V. V. Burlakov, B. Heller, W. Baumann, A. Spannenberg, R. Kempe, U. Rosenthal, R. Beckhaus
Terminal Alkynes in the Coordination Sphere of Titanocene Complexes - Elementary Steps in Catalytic Dimerizations and Oligomerizations of Alkynes
Z. anorg. allg. Chem. 1998, 624, 129 - 134.

27. D. Thomas, N. Peulecke,  V. V. Burlakov, B. Heller, W. Baumann, A. Spannenberg, R. Kempe, U. Rosenthal, R. Beckhaus
Katalysatordesaktivierungen in der Acetylen-Polymerisation mit Titanocen- und Zirconocen-Komplexen des Bis(trimethylsily) acetylens
Z. anorg. allg. Chem. 1998, 624, 919 - 924.

26. R. Beckhaus, J. Oster, R. Wang, U. Böhme
Synthesis of Semibridging m-Vinylidene Titanium-Copper and -Gold Complexes. Crystal and Molecular Structure of Cp*2Ti(Cl)(μ-C=CH2)AuPPh3
Organometallics, 1998, 17, 2215 - 2221. 

25. R. Beckhaus, M. Wagner, R. Wang
Darstellung und Kristallstruktur des Azavinylidenderivates Cp*2Ti(CH=CH2)(N=CPh2) ausgehend vom thermisch gebildeten Titanaallenintermediate[Cp*2Ti=C=CH2]
Z. anorg. allg. Chem., 1998, 624, 277 - 280.

24. R. Beckhaus, M. Wagner, U. Rosenthal, R. Kempe, A. Spannenberg, W. Baumann
Terminal Alkynes in the Coordination Sphere of Titanocene Complexes - Elementary Steps in Catalytic Dimerizations and Oligomerizations of Alkynes
Z. anorg. allg. Chem., 1998, 624, 129 - 134.

23. R. Beckhaus, M. Wagner, R. Wang
Synthesis and Structural Characterization of Azatitanacyclobutane Derivatives
Eur. J. Inorg. Chem. 1998, 253 - 256. 

1997

22. R. Beckhaus, J. Oster, B. Ganter, U. Englert
Vinyltitanium Complexes Containing the [2-(N,N-Dimethyl-amino)ethyl]tetramethylcyclopentadienyl Ligand Cp*N - Generation and Reactivity of the Vinylidene Intermediate, [(Cp*N)(Cp*)Ti=C=CH2] (Cp*N = η5-C5Me4(CH2)2NMe2, Cp* = η5-C5Me5)
Organometallics, 1997, 16, 3902 - 3909.

21. R. Beckhaus, J. Sang, T. Wagner, U. Böhme
Regioselective Reactions of Isothiocyanates with the Titanocene Vinylidene Fragment [Ti(=C=CH2)(η-C5Me5)2]. Crystal and Molecular Structure of [Ti{SC(=N(C6H11)C=CH2}(η-C5Me5)2]
J. Chem. Soc. Dalton Trans., 1997, 2249 - 2256. 

20. R. Beckhaus
C2 Building Blocks in the Coordination Sphere of Electron Poor Transition Metals. Aspects of the Chemistry of Early-Transition-Metal Carbenoide Complexes
J. Chem. Soc. Dalton Trans., 1997, 1991 - 2002. 

19. R. Beckhaus, I. Strauß, T. Wagner
Darstellung und Kristallstrukturanalyse von Bis(p-pentamethylcyclopentadienyl)(2-methylen)- (3-diphenylmethylen)oxatitanacyclobutan Cp*2TiOC(=CPh2)CC=CH2
Z. anorg. allg. Chem. 1997, 623, 654 - 658. 

18. R. Beckhaus
Carbenoide Komplexverbindungen elektronenarmer Übergangsmetalle - Synthesen von und mit kurzlebigen Synthesebausteinen
Angew. Chem. 1997, 109, 694 - 722; Angew. Chem., Int. Ed. Engl. 1997, 36, 686 - 713.

17. R. Beckhaus, J. Oster, J. Sang, I. Strauß, M. Wagner
The Story of 1-Alkenyl Complexes of Early Transition Metals - A Low Temperature Access to the Versatile Titana-Allene Building Block [Cp*2Ti=C=CH2]
Synlett 1997, 3, 241 - 249. 

1995

13. R. Beckhaus, J. Oster, R. Loo
a-H-Übertragungen an Vinylmetallverbindungen - Darstellung von (h5-Cyclopentadienyl(h5-pentamethylcyclopentadienyl)- (2-methyliden)titanacyclobutan
J. Organometal. Chem. 1995, 501, 321 - 326.

12. R. Beckhaus, I. Strauß, T. Wagner,
Synthese und Struktur von 1-Aza- und 1-Phospha-2-titanacyclobut-4-enen
Angew. Chem. 1995, 107, 738 - 740; Angew. Chem., Int. Ed. Engl. 1995, 34, 688 - 690.

11. R. Beckhaus, J. Oster
Zur Reaktivität isomerer heterodinuclearer Fischer-Carben Komplexe mit Titanaoxetan- und Titanaoxolenteilstrukturen - Cycloreversions- und Insertionsreaktionen
Z. anorg. allg. Chem. 1995, 621, 359 - 364. 

1993

7. R. Beckhaus, I. Strauß, T. Wagner, P. Kiprof
Überraschende Differenzierung bei der Cycloaddition von Cumulenen und Heterocumulenen an ein Vinylidentitanocen: Bildung vier- und fünfgliedriger Titanacyclen
Angew. Chem. 1993, 105, 281-283; Angew. Chem., Int. Ed. Engl. 1993, 32, 264 - 266. 

6. R. Beckhaus, T. Wagner, C. Zimmermann, E. Herdtweck
Bis(π-pentamethylcyclopentadienyl)(2-methyliden)titanacyclobutan: Selektive Insertion von Isonitrilen und Diphenylketen - Bildung fünf- und sechsgliedriger Metallacyclen
J. Organometal. Chem. 1993, 460, 181 - 189. 

5. D. Selent, R. Beckhaus, J. Pickardt
Heterodinuclear Titanium-Cobalt Complexes: Syntheses and Properties. X-ray Structure of [(tert.-C4H9O)3TiCo(CO)4] (Ti-Co)
Organometallics 1993, 12,
2857 - 2860.

4. R. Beckhaus
Methylidenetitanacyclobutane vs. Titanocene-Vinylidene - Versatile Building Blocks
Organic Synthesis via Organometallics (OSM 4), Proceedings of the Fourth Symposium in Aachen, July 15th to 18th, 1992, D. Enders, H.-J. Gais, W. Keim (Hrsg.),
Vieweg Verlag, Braunschweig 1993, 131 - 149. 

1991

3. D. Selent, R. Beckhaus, T. Bartik
Synthese und Charakterisierung eines stabilen heterobimetallischen Titan-Cobalt Komplexes mit unverbrückter Ti-Co-Bindung

J. Organometal. Chem.
1991, 405, C15 - C18.

2. R. Beckhaus
Zur Chemie von Vinylverbindungen elektronenarmer Übergangsmetalle
(Habilitation Thesis),
Fakultät für Naturwissenschaften, Technische Hochschule Leuna-Merseburg; Mathematisch-Naturwissen-schaftliche Fakultät der RWTH Aachen; 1991/1993.