Aggregation and contingent metal/surface reactivity of 1,3,8,10- tetraazaperopyrene (TAPP) on Cu(111)

Chemistry - A European Journal

Volumn 16, Issue 7, 2010, Pages 2079-2091

  Matena, Manfred ^a   Stöhr, Meike ^a   Riehm, Till ^c   Björk, Jonas ^e   Martens, Susanne ^c   Dyer, Matthew S ^e   Persson, Mats ^e,f   Lobo Checa, Jorge ^a,b   Müller, Kathrin ^d   Enache, Mihaela ^a   Wadepohl, Hubert ^c   Zegenhagen, Jörg ^g   Jung, Thomas A ^d   Gade, Lutz H ^c  

^a UNIVERSITY OF BASEL   (Switzerland)

^b CATALAN INSTITUTE OF NANOSCIENCE AND NANOTECHNOLOGY ICN2   (Spain)

^c UNIVERSITY OF HEIDELBERG   (Germany)

^d PAUL SCHERRER INSTITUTE   (Switzerland)

^e UNIVERSITY OF LIVERPOOL   (United Kingdom)

^f CHALMERS UNIVERSITY OF TECHNOLOGY   (Sweden)

^g EUROPEAN SYNCHROTRON RADIATION FACILITY   (France)

Author keywords

Aggregation; C H activation; Coordination networks; Density functional calculations; Surface chemistry

Indexed keywords

BULK STRUCTURE; C-H ACTIVATION; CLOSE-PACKED ASSEMBLY; COORDINATION NETWORKS; COPPER SURFACE; COVALENT COUPLINGS; CU ATOMS; CU SUBSTRATE; CU(1 1 1); DENSITY-FUNCTIONAL CALCULATIONS; DEPOSITION CONDITIONS; DFT CALCULATION; ELEVATED TEMPERATURE; EXPERIMENTAL TECHNIQUES; INTERMOLECULAR INTERACTIONS; METAL ADATOMS; METAL COORDINATION; MOLECULAR CHAINS; POROUS NETWORKS; REACTION CHANNELS; REACTION PRODUCTS; SCANNING TUNNELING MICROSCOPY (STM); STRUCTURAL CHEMISTRY; SUBMONOLAYER COVERAGE; SURFACE TRANSFORMATIONS; VAN DER WAALS; WEAK HYDROGEN BOND; XPS;

ACTIVATION ANALYSIS; CAPILLARITY; COORDINATION REACTIONS; HYDROGEN BONDS; REACTION KINETICS; SCANNING TUNNELING MICROSCOPY; SULFUR COMPOUNDS; SURFACE CHEMISTRY; SURFACES; VAN DER WAALS FORCES; X RAY PHOTOELECTRON SPECTROSCOPY;

AGGLOMERATION;

EID: 76449095529     PISSN: 09476539     EISSN: 15213765     Source Type: Journal    
DOI: 10.1002/chem.200902596     Document Type: Article

References (168)

1. For selected recent overviews covering various aspects of the field, see: a) J. V. Barth, G. Costantini, K. Kern, Nature 2005, 437, 671;
2. b) K.-H. Ernst, Top. Curr. Chem. 2006, 265, 209;
3. c) K. Müllen, J. P. Rabe, Acc. Chem. Res. 2008, 41, 511;
4. d) D. Li, R. B. Kaner, Science 2008, 320, 1170;
5. e) M. Treier, R. Fasel, Chimia 2009, 63, 122;
6. f) J. A. A. W. Elemans, S. Lei, S. De Feyter, Angew. Chem. 2009, 121, 7434;
7. Angew. Chem. Int. Ed. 2009, 48, 7298.
8. a) J. Sakamoto, J. van Heijst, O. Lukin, A. D. Schlüter, Angew. Chem. 2009, 121, 1048;
9. Angew. Chem. Int. Ed. 2009, 48, 1030;
10. b) D. F. Perepichka, F. Rosei, Science 2009, 323, 216;
11. c) A. Gourdon, Angew. Chem. 2008, 120, 7056;
12. Angew. Chem. Int. Ed. 2008, 47, 6950.
13. Selected key references: a) C. Joachim, J. K. Gimzewski, A. Aviram, Nature 2000, 408, 541;
14. b) C. D. Dimitrakopoulos, P. R. L. Malenfant, Adv. Mater. 2002, 14, 99;
15. c) L. Venkataraman, J. E. Klare, C. Nuckolls, M. S. Hybertsen, M. L. Steigerwald, Nature 2006, 442, 904;
16. d) B. Crone, A. Dodabalapur, Y.-Y. Lin, R. W. Filas, Z. Bao, A. LaDuca, R. Sarpeshkar, H. E. Katz, W. Li, Nature 2000, 403, 521;
17. e) L. Fu, L. Cao, Y. Liu, D. Zhu, Adv. Colloid Interface Sci. 2004, 111, 133.
18. a)J.-M. Lehn, Supramolecular Chemistry -Concepts and Perspectives, VCH, Weinheim, 1995.
19. See also: b) J.-M. Lehn, Science 2002, 295, 2400;
20. c) O. Ikkala, G. tenBrinke, Science 2002, 295, 2407;
21. d) D.N. Reinhoudt, M. Crego-Calama, Science 2002, 295, 2403;
22. e)G. M. Whitesides, B. Grzybowski, Science 2002, 295, 2418;
23. f) M. D. Hollingsworth, Science 2002, 295, 2410;
24. g) T. Kato, Science 2002, 295, 2414;
25. h) M. Ruben, J. Rojo, F. J. Romero-Salguero, L. H. Uppadine, J.-M. Lehn, Angew. Chem. 2004, 116, 3728;
26. Angew.Chem. Int. Ed. 2004, 43, 3644.
27. Selected examples: SPM: a) G. Binnig, H. Rohrer, Rev. Mod. Phys. 1987, 59, 615;
28. b) F. J. Giessibl, Rev. Mod. Phys. 2003, 75, 949. Photoelectron spectroscopy:
29. c) S. Hüfner, Photoelectron Spectroscopy - Principles and Applications, Springer, Heidelberg, 2003. General overview of surface science techniques:
30. d) K. Oura, V. G. Lifshits, A. A. Saranin, A. V. Zotov, M. Katayama, Surface Science: An Introduction, Springer, Berlin 2003.
31. a) R. Lazzaroni, A. Calderone, J. L. Brédas, J. P. Rabe, J. Chem. Phys. 1997, 107, 99;
32. b) M. Elstner, D. Porezag, G. Jungnickel, J. Eisner, M. Haugk, T. Frauenheim, S. Suhai, G. Scifert, Phys. Rev. B 1998, 58, 7260;
33. c)X. Wu, M. C. Vargas, S. Nayak, V. Lotrich, G. Scoles, J. Chem. Phys. 2001, 115, 8748;
34. d) W. A. Hofer, A. S. Foster, A. L. Shluger, Rev. Mod. Phys. 2003, 75, 1287.
35. a) J. V. Barth, Annu. Rev. Phys. Chem. 2007, 58, 375;
36. b) L. Grill, J. Phys. Condens. Matter 2008, 20, 053001;
37. c) S. Stepanow, N. Lin, J. V. Barth, J. Phys. Condens. Matter 2008, 20, 184002;
38. d) A. Kühnle, Curr. Opin. Colloid Interface Sci. 2009 ,14, 157.
39. a) S. DeFeyter, F. C. De Schryver, Chem. Soc. Rev. 2003, 32, 139;
40. b) S. De Feyter, F. C. De Schryver, J. Phys. Chem. B 2005, 109, 4290;
41. c) L.-J. Wan, Acc. Chem. Res. 2006, 39, 334;
42. d) S. Yoshimoto, Bull. Chem. Soc. Jpn. 2006, 79, 1167;
43. e) U Ziener, Phys. Chem. B 2008, 112, 14698.
44. a) F. Rosei, M. Schunack, Y. Naitoh, P. Jiang, A. Gourdon, E. Laegsgaard, I. Stensgaard, C. Joachim, F. Besenbacher, Prog. Surf. Sci. 2003, 71, 95;
45. b) F. S. Tautz, Prog. Surf. Sci. 2007, 82, 479.
46. a) M. Böhringer, K. Morgenstern, W.-D. Schneider, R. Berndt, F. Mauri, A. D. Vita, R. Car, Phys. Rev. Lett. 1999, 83, 324;
47. b) S. Ito, M. Wehmeier, J. D. Brand, C. Kubel, R. Epsch, J. P. Rabe, K. Müllen, Chem. Eur. J. 2000, 6, 4327;
48. c) T. Yokoyama, S. Yokoyama, Y. Okuno, S. Mashiko, Nature 2001, 413, 619;
49. d) A. Langner, S. L. Tait, N. Lin, C. Rajadurai, M. Ruben, K. Kern, Proc. Natl. Acad. Sci. USA 2007, 104, 17927.
50. a) J. Weckesser, A.D. Vita, J.V. Barth, C. Cai, K. Kern, Phys. Rev. Lett. 2001, 87, 096101;
51. b) H. Spillmann, A. Dmitriev, N. Lin, P. Messina, J. V. Barth, K. Kern, J. Am. Chem. Soc. 2003, 125, 10725;
52. c) M. de Wild, S. Berner, H. Suzuki, H. Yanagi, D. Schlettwein, S. Ivan, A. Baratoff, H.-J. Güntherodt, T. A. Jung, ChemPhysChem 2002, 3, 881;
53. d) S. De Feyter, M. Larsson, N. Schuurmans, B. Verkuijl, G. Zoriniants, A. Gesquière, M. M. Abdel-Mottaleb, J. van Esch, B. L. Feringa, J. vanStam, F. De Schryver, Chem. Eur. J. 2003, 9, 1198;
54. e) D. Bonifazi, H. Spillmann, A. Kiebele, M. de Wild, P. Sciler, F. Cheng, H.-J. Güntherodt, T. Jung, F. Diederich, Angew. Chem. 2004;
55. Angew. Chem. Int. Ed. 2004, 43, 4759;
56. f) M. E. Cañas-Ventura, W. Xiao, D. Wasserfallen, K. Müllen, H. Brune, J. V. Barth, R. Fasel, Angew. Chem. 2007, 119, 1846;
57. Angew. Chem. Int. Ed. 2007, 46, 1814.
58. Selected references: a) J. A. Theobald, N. S. Oxtoby, M. A. Phillips, N. R. Champness, P. H. Beton, Nature 2003, 424, 1029.
59. See also: b)F. Cicoira, C. Santato, F. Rosei, Top. Curr. Chem. 2008, 285, 203;
60. c) A. Ziegler, W. Mamdouh, A. Ver Heyen, M. Surin, H. Ujii, M. M. S. Abdel-Mottaleb, F. C. De Schryver, S. De Feyter, R. Lazzaroni, S. Höger, Chem. Mater. 2005, 17, 5670;
61. d) S. Griessl, M. Lackinger, M. Edelwirth, M. Hietschold, W. M. Heckl, Single Mol. 2002, 3, 25;
62. e) G. Pawin, K. L. Wong, K.-Y. Kwon, L. Bartels, Science 2006, 313, 961;
63. f) H. Spillmann, A. Kiebele, M. Stöhr, T. A. Jung, D. Bonifazi, F. Cheng, F. Diederich, Adv. Mater. 2006, 18, 275;
64. g) M. Wahl, M. Stöhr, H. Spillmann, T. A. Jung, L. H. Gade, Chem. Commun. 2007, 1349;
65. h) U Schlickum, R. Decker, F. Klappenberger, G. Zoppellaro, S. Klyatskaya, M. Ruben, I. Silanes, A. Arnau, K. Kern, H. Brune, J. V. Barth, Nano Lett. 2007, 7, 3813;
66. i) S. Furukawa, H. Ujii, K. Tahara, T. Ichikawa, M. Sonoda, F. C. De Schryver, Y. Tobe, S. DeFeyter, J. Am. Chem. Soc. 2006, 128, 3502;
67. j)M. Stöhr, M. Wahl, H. Spillmann, L. H. Gade, T. A. Jung, Small 2007, 3, 1336;
68. k) S. Lei, K. Tahara, X. Feng, S. Furukawa, F. C. De Schryver, K. Müllen, Y. Tobe, S. De Feyter, J. Am. Chem. Soc. 2008, 130, 7119.
69. Recent reviews: a) N. Lin, S. Stepanow, M. Ruben, J. V. Barth, Top. Curr. Chem. 2009, 275-278, 1;
70. b) J. V. Barth, Surf. Sci. 2009, 603, 1533.
71. Selected examples: a) A. Dmitriev, H. Spillmann, N. Lin, J. V. Barth, K. Kern, Angew. Chem. 2003, 115, 2774
72. Angew. Chem. Int. Ed. 2003, 42, 2670;
73. b) M. A. Lingenfelder, H. Spillmann, A. Dmitriev, S. Stepanow, N. Lin, J. V. Barth, K. Kern, Chem. Eur. J. 2004, 10, 1913;
74. c) N. Lin, S. Stepanow, F. Vidal, J. V. Barth, K. Kern, Chem. Commun. 2005, 1681;
75. d) T. Classen, G. Fratesi, G. Costantini, S. Fabris, F. Stadler, C. Kim, S. de Gironcoli, S. Baroni, K. Kern Angew. Chem. 2005, 117, 6298;
76. Angew. Chem. Int. Ed. 2005, 44, 6142;
77. Angew. Chem. Int. Ed. 2005, 44, 6142;
78. e) N. Lin, S. Stepanow, F. Vidal, K. Kern, M. S. Alam, S. Strömsdörfer, V. Dremov, P. Müller, A. Landa, M. Ruben, Dalton Trans. 2006, 2794;
79. f) S. Stepanow, N. Lin, D. Payer, U. Schlickum, F. Klappenberger, G. Zoppel- laro, M. Ruben, H. Brune, J. V. Barth, K. Kern, Angew. Chem. 2007, 119, 724;
80. Angew. Chem. Int. Ed. 2007, 46, 710;
81. g) S. Tait, A. Langner, N. Lin, S. Stepanow, C. Rajadurai, M. Ruben, K. Kern, J. Phys. Chem. C 2007, 111, 10982;
82. h) A. Langner, S. L. Tait, N. Lin, R. Chandrasekar, M. Ruben, K. Kern, Angew. Chem. 2008, 120, 8967;
83. Angew. Chem. Int. Ed. 2008, 47, 8835;
84. i) S. L. Tait, A. Langner, N. Lin, R. Chandrasekar, M. Ruben, K. Kern, ChemPhysChem 2008, 9, 2594;
85. j) D. Kühne, F. Klappenberger, R. Decker, U. Schlickum, H. Brune, S. Klyatskaya, M. Ruben, J. V. Barth, J. Am. Chem. Soc. 2009, 131, 3881;
86. k) A. Langner, S. Tait, N. Lin, R. Chandrasekar, M. Ruben, K. Kern, Chem. Commun. 2009, 2502.
87. R. F. W. Bader, Atoms in Molecules-A Quantum Theory, Clarendon Press, Oxford, 1994.
88. a) S. W. HIa, L. Bartels, G. Meyer, K. H. Rieder, Phys. Rev. Lett. 2000, 85, 2777;
89. b) Y. Okawa, M. Aono, Nature 2001, 409, 683;
90. c) H. Ozaki, T. Funaki, Y. Mazaki, S. Masuda, Y. Harada, J. Am. Chem. Soc. 1995, 117, 5596.
91. a) S. Weigelt, C. Busse, C. Bombis, M. M. Knudsen, K. V. Gothelf, T. Strunskus, C. WoIl, M. Dahlboom, B. Hammer, E. Laegsgaard, F. Besenbacher, T. R. Linderoth, Angew. Chem. 2007, 119, 9387;
92. Angew. Chem. Int. Ed. 2007, 46, 9227;
93. b) N. A. A. Zwaneveld, R. Pawlak, M. Abel, D. Catalin, D. Gigmes, D. Bertin, L. Porte, J. Am. Chem. Soc. 2008, 130, 6678;
94. c) S. Boz, M. Stöhr U. Soydaner, M. Mayor, Angew. Chem. 2009,121, 3225;
95. Angew. Chem. Int. Ed. 2009, 48, 3179;
96. d) C. H. Schmitz, J. Ikonomov, M. Sokolowski, J. Phys. Chem. C 2009, 113, 11984.
97. a) L. Grill, M. Dyer, L. Lafferentz, M. Persson, M. V. Peters, S. Hecht, Nat. Nanotechnol. 2007, 2, 687;
98. b) M. In't Veld, P. Iavicoli, S. Haq, D. B. Amabilino, R. Raval, Chem. Commun. 2008, 1536.
99. M. Matena, T. Riehm, M. Stöhr, T. A. Jung, L. H. Gade, Angew. Chem. 2008, 120, 2448;
100. Angew. Chem. Int. Ed. 2008, 47, 2414.
101. T. Riehm, G. DePaoli, A. Konradsson, L. de Cola, H. Wadepohl, L. H. Gade, Chem. Eur. J. 2007, 13, 7317.
102. a) G. R. Desiraju, A. Gavezotti, Acta Crystallogr. Sect. B 1989, 45, 473;
103. G. R. Desiraju, A. Gavezotti, J. Chem. Soc. Chem. Commun. 1989, 621 ;
104. b) D. M. Cho, S. R. Parkin, M. D. Watson, Org. Lett. 2005, 7, 106
105. c) C. A. Hunter, K. R. Lawson, J. Perkins, C. J. Urch, J. Chem. Soc. Perkin Trans. 2 2001, 651;
106. d) M. D. Curtis, J. Cao, J. W. Kampf, J. Am. Chem. Soc. 2004, 126, 4318;
107. e) G. Horowitz, B. Bachet, A. Yassar, P. Lang, F. Demanze, J.-L. Fave, F. Garnier, Chem. Mater. 1995, 7, 1337;
108. f) D. Fichou, J. Mater. Chem. 2000, 10, 571.
109. a) G. R. Desiraju, T. Steiner, The Weak Hydrogen Bond in Structural Chemistry and Biology, Oxford University Press, New York, 1999;
110. b) M. Mascai, Chem. Commun. 1998, 303;
111. c) F. A. Cotton, L. M. Daniels, G. T. Jordan IV, C. A. Murillo, Chem. Commun. 1997, 1673;
112. d) R. Taylor, O. Kennard, J. Am. Chem. Soc. 1982, 104, 5063;
113. e) V. R. Thalladi, A. Gehrke, R. Boese, New J. Chem. 2000, 24, 463;
114. f) R. Cini, C. Bellucci, G. Tamasi, M. Corsini, M. Fontani, P. Zanello, Inorg. Chim. Acta 2002, 339, 89;
115. g) M. Hartmann, L. Radom, J. Phys. Chem. A 2000, 104, 968.
116. a) R. E. Franklin, Acta Crystallogr. 1951, 4, 253;
117. b) G. E. Bacon, Acta Crystallogr. 1951, 4, 458.
118. K. Glöckler, C. Scidel, A. Soukopp, M. Sokolowski, E. Umbach, M. Böhringer, R. Berndt, W. D. Schneider, Surf. Sci. 1998, 405, 1.
119. LEED pattern simulator: LEEDpat Version 2.1, K. Hermann, M. A. van Hove, 2006.
120. D. E. Hooks, T. Fritz, M. D. Ward, Adv. Mater. 2001, 13, 227.
121. M. Giesen, Surf. Sci. 1999, 442, 543.
122. a) F. H. Allen, O. Kennard, Chem. Des. Autom. News 1993, 8, 1631;
123. b)D. A. Fletcher, R. F. McMeeking, D. J. Parkin, J. Chem. Inf. Comput. Sci. 1996, 36, 746.
124. See also: L. H. Gade, Koordinationschemie, Wiley-VCH, Weinheim, 1998.
125. C. C. Perry, S. Haq, B. G. Frederick, N. V. Richardson, Surf. Sci. 1998, 409, 512.
126. a) S. Stepanow, M. Lingenfelder, A. Dmitriev, H. Spillmann, E. Delvigne, N. Lin, X. Deng, C. Cai, J. V. Barth, K. Kern, Nat. Mater. 2004, 3, 229;
127. b) S. Stepanow, N. Lin, J. V. Barth, K. Kern, J. Phys. Chem. B 2006, 110, 23472.
128. J. V. Barth, J. Weckesser, N. Lin, A. Dmitriev, K. Kern, Appl. Phys. A 2003, 76, 645.
129. N. Lin, A. Dmitriev, J. Weckesser, J. V. Barth, K. Kern, Angew. Chem. 2002, 114, 4973;
130. Angew. Chem. Int. Ed. 2002, 41, 4779.
131. a) M. Schunack, F. Rosei, Y. Naitoh, P. Jiang, A. Gourdon, E. Laegsgaard, I. Stensgaard, C. Joachim, F. Besenbacher, J. Chem. Phys. 2002, 117, 6259. A fundamental study on the energies controlling surface restructuring processes on Ag (111) has been published by Morgenstern et al.:
132. b) K. Morgenstern, G. Rosenfeld, E. Laengsgaard, F. Besenbacher, G. Comsa, Phys. Rev. Lett. 1998, 80, 556.
133. M. Giesen, Prog. Surf Sci. 2001, 68, 1.
134. M. Giesen, G. Icking-Konert, Surf Sci. 1998, 412-413, 645.
135. H.-W. Wanzlick, Angew. Chem. 1962, 74, 129;
136. Angew. Chem. Int. Ed. Engl. 1962, 1, 75.
137. Y. Hasegawa, P. Avouris, Phys. Rev. Lett. 1993, 71, 1071.
138. M. F. Crommie, C. P. Lutz, D. M. Eigler, Nature 1993, 363, 524.
139. a) E. Alvarez, S. Conejero, M. Paneque, A. Petronilho, M. L. Pověda, O. Serrano, E. Carmona, J. Am. Chem. Soc. 2006, 128, 13060; an analogous reaction has been reported for a quinoline derivative inter alia:
140. b) M. Esteruelas, F.J. Fernandez-Alvarez, E. Oñate, J. Am. Chem. Soc. 2006, 128, 13044; review:
141. c) D. Kunz, Angew. Chem. 2007, 119, 3473;
142. Angew. Chem. Int. Ed. 2007, 46, 3405.
143. a) J. C. Y. Lin, R. T. W. Huang, C. S. Lee, A. Bhattacharyya, W. S. hwang, I. J. B. Lin, Chem. Rev. 2009, 109, 3561;
144. b) S. Diez-Gonzalez, N. Marion, S. P. Nolan, Chem. Rev. 2009, 109, 3612;
145. c) S. Diez-González, S. P. Nolan, Acc. Chem. Res. 2008, 41, 349;
146. d) N-Heterocyclic Carbenes in Syntheses (Ed.: S. P. Nolan), Wiley-VCH, Weinheim, 2006;
147. e)S.P. Nolan, Chem. Eur. J. 2008, 14, 158;
148. f) P. L. Arnold, Heteroat. Chem. 2002, 13, 534;
149. g) C. Nolte, P. Mayer, B. F. Straub, Angew. Chem. 2007, 119, 2147;
150. Angew. Chem. Int. Ed. 2007, 46, 2101.
151. M. Stöhr, M. Wahl, C. H. Galka, T. Riehm, T. A. Jung, L. H. Gade, Angew. Chem. 2005, 117, 7560;
152. Angew. Chem. Int. Ed. 2005, 44, 7394.
153. I. Horcas, R. Fernández, J. M. Gómez-Rodríguez, J. Colchero, Rev. Sci. Instrum. 2007, 78, 013705.
154. G. Kresse, J. J. Furthmüller, Phys. Rev. B 1996, 54, 11169.
155. a) P. E. Blüchl, Phys. Rev. B 1994, 50, 17593;
156. b) G. Kresse, D. Joubert, Phys. Rev. B 1999, 59, 1758.
157. P. Perdew, J. A. Chevary, S. H. Vosko, K. A. Jackson, M. R. Pederson, D. J. Singh, C. Fiolhais, Phys. Rev. B 1992, 46, 6671.
158. a) J. Tersoff, D. R. Hamann, Phys. Rev. B 1985, 31, 805;
159. b) J. Tersoff, D. R. Hamann, Phys. Rev. Lett. 1983, 50, 1998.
160. W. Sacks, S. Gauthier, S. Rousset, J. Klein, M. A. Erck, Phys. Rev. B 1987, 36, 961.
161. L. Köhler, G. Kresse, Phys. Rev. B 2004, 70, 165405.
162. B. Johansson, N. Mârtensson, Phys. Rev. B 1980, 21, 4427.
163. SAINT, Bruker AXS, 1997-2008.
164. R. H. Blessing, Acta Crystallogr. Sect. A 1995, 51, 33.
165. SADABS, G. M. Sheldrick, Bruker AXS, 2004-2008.
166. SHELXS-97, G. M. Sheldrick, University of Göttingen, Göttingen, 1997.
167. G. M. Sheldrick, Acta Crystallogr. Sect. A 2008, 64, 112.
168. SHELXL-97, G. M. Sheldrick, University of Göttingen, Göttingen, 1997.