Reduction of Dicarbapentaboranes(5) to 1,2-Diborata-4-boracyclopentadienes: Antiaromatic Compounds with 4π-Electron Systems

Angewandte Chemie (International Edition in English)

Volumn 36, Issue 8, 1997, Pages 853-855

  Unverzagt, Markus ^a   Winkler, Heinz Jürgen ^a   Brock, Michael ^a   Hofmann, Matthias ^b   Von Ragué Schleyer, Paul ^b   Massa, Werner ^a   Berndt, Armin ^a  

^a PHILIPPS UNIVERSITY MARBURG   (Germany)

^b UNIVERSITY OF ERLANGEN NUREMBERG   (Germany)

Author keywords

Ab initio calculations; Aromaticity; Boron; Carboranes

Indexed keywords

EID: 0031007312     PISSN: 05700833     EISSN: None     Source Type: Journal    
DOI: 10.1002/anie.199708531     Document Type: Article

References (32)

1. R. W. Rudolph, W. R. Pretzer, Inorg. Chem. 1972, 11, 1974-1978; R. W. Rudolph, Acc. Chem. Res. 1976, 9, 446-452.
2. R. W. Rudolph, W. R. Pretzer, Inorg. Chem. 1972, 11, 1974-1978; R. W. Rudolph, Acc. Chem. Res. 1976, 9, 446-452.
3. a) R. Köster, G. Seidel, B. Wrackmeyer, Angew. Chem. 1984, 96, 520-521, Angew. Chem. Int. Ed. Engl. 1984, 23, 512;
4. a) R. Köster, G. Seidel, B. Wrackmeyer, Angew. Chem. 1984, 96, 520-521, Angew. Chem. Int. Ed. Engl. 1984, 23, 512;
5. b) R. Köster, G. Seidel, B. Wrackmeyer, ibid. 1985, 97, 317-318 and 1985, 24, 317-318;
6. b) R. Köster, G. Seidel, B. Wrackmeyer, ibid. 1985, 97, 317-318 and 1985, 24, 317-318;
7. c) R. Köster, G. Seidel, B. Wrackmeyer, D. Bläser, R. Boese, M. Bühl, P. von R. Schleyer, Chem. Ber. 1991, 124, 2715-2724.
8. a) R. E. Williams, Inorg. Chem. 1971, 10, 210-214;
9. b) Chem. Rev. 1992, 92, 177-207.
10. J. Allwohn, M. Pilz, R. Hunold, W. Massa, A. Berndt, Angew. Chem. 1990, 102, 1084-1086, Angew. Chem. Int. Ed. Engl. 1990, 29, 1032.
11. J. Allwohn, M. Pilz, R. Hunold, W. Massa, A. Berndt, Angew. Chem. 1990, 102, 1084-1086, Angew. Chem. Int. Ed. Engl. 1990, 29, 1032.
12. 11B NMR data of the reduction product of pentaethyldicarbapentaborane. δ = -14.2 and -37.1, differ strongly from the values computed for 2u-4u and 8. Therefore, a pyramidal structure can definitively be ruled out. The reduction product may be a dimer of a radical anion of pentaethyldicarbapentaborane.
13. -3. A Flack Parameter x = 0.00(1) proves that the correct enantiomer has been refined. The crystallographic data (without structure factors) were deposited as "supplementary publication no. CCDC-179-165 at the Cambridge Crystallographic Data Center. Copies of the data can be requested free of charge from: The Director, CCDC. 12 Union Road, Cambridge CB2 1EZ, UK (Fax: Int. code +(1223)336-033; e-mail: deposits chemcrys.cam.ac.uk).
14. [7) Relative energies correspond to MP2(fc)/6-31 + G* +0.93 ZPE data. Geometry optimizations and frequency calculations were performed with Gaussian 94: M. J. Frisch, G. W. Trucks, H. B. Schlegel, P. M. W. Gill, B. G. Johnson, M. A. Robb, J. R. Cheeseman, T. Keith, J. A. Petersson, J. A. Montgomery, K. Raghavachari, M. A. Al-Laham, V. G. Zakrzewski, J. Y. Ortiz, J. B. Foresman, J. Cioslowski, B. B. Stefanov, A. Nanayakkara, M. Challcombe, C. Y. Peng, P. Y. Ayala, W. Chen, M. W. Wong, J. L. Andres, E. S. Replogle, R. Gomperts. R. L. Martin, D. J. Fox, J. S. Blinkley, D. J. DeFrees, J. Baker, J. J. P. Stewart, M. Head-Gordon, C. Gonzalez, J. A. Pople, Gaussian Inc., Pittsburgh, PA, 1995.
15. GIAO-MP2: a) J. Gauss, Chem. Phys. Lett. 1992, 191, 614;
16. b) J. Gauss, J. Chem. Phys. 1993, 99, 3629-3643. The method was implemented in ACESII (ACESII, an ab initio program: J. F. Stanton, J. Gauss, J. D. Watts, W. J. Lauderdale, R. J. Bartlett, Quantum Theory Project, University of Florida, Fl, 1991, 1992). The abbreviation tzpdz designates triple-zeta plus polarization basis sets for heavy elements and double-zeta for hydrogen: A. Schäfer, H. Horn, R. Ahlrichs, J. Chem. Phys. 1992, 97, 2571-2577.
17. b) J. Gauss, J. Chem. Phys. 1993, 99, 3629-3643. The method was implemented in ACESII (ACESII, an ab initio program: J. F. Stanton, J. Gauss, J. D. Watts, W. J. Lauderdale, R. J. Bartlett, Quantum Theory Project, University of Florida, Fl, 1991, 1992). The abbreviation tzpdz designates triple-zeta plus polarization basis sets for heavy elements and double-zeta for hydrogen: A. Schäfer, H. Horn, R. Ahlrichs, J. Chem. Phys. 1992, 97, 2571-2577.
18. b) J. Gauss, J. Chem. Phys. 1993, 99, 3629-3643. The method was implemented in ACESII (ACESII, an ab initio program: J. F. Stanton, J. Gauss, J. D. Watts, W. J. Lauderdale, R. J. Bartlett, Quantum Theory Project, University of Florida, Fl, 1991, 1992). The abbreviation tzpdz designates triple-zeta plus polarization basis sets for heavy elements and double-zeta for hydrogen: A. Schäfer, H. Horn, R. Ahlrichs, J. Chem. Phys. 1992, 97, 2571-2577.
19. + square pyramid: M. N. Glukhovtsev, B. Reindl, P. von R. Schleyer, Mendeleev Commun. 1993, 100-101.
20. P. von R. Schleyer, P. K. Freeman, H. Jiao, B. Goldfuss, Angew. Chem. 1995, 107, 332-335, Angew. Chem. Int. Ed. Engl. 1995, 34, 337.
21. P. von R. Schleyer, P. K. Freeman, H. Jiao, B. Goldfuss, Angew. Chem. 1995, 107, 332-335, Angew. Chem. Int. Ed. Engl. 1995, 34, 337.
22. A gallacyclopentadiene with a long single bond between short C=C double bonds is described in: A. H. Cowley, F. P. Gabbai, A. Decken, Angew. Chem. 1994, 106, 1429-1431. Angew. Chem. Im. Ed. Engl. 1994, 33, 1370.
23. A gallacyclopentadiene with a long single bond between short C=C double bonds is described in: A. H. Cowley, F. P. Gabbai, A. Decken, Angew. Chem. 1994, 106, 1429-1431. Angew. Chem. Im. Ed. Engl. 1994, 33, 1370.
24. 2 substituent on the boron atom between the C atoms of 5u has no significant influence on the C-B distances in the ring, even if it conjugates with the B atom (B-N 149.7 pm, B-N-H 115.2°; C-B 150.2, 155.9) or is twisted by 90 (B-N 157.4pm, B-N-H 104.5°; C-B 150.4, 154.5 pm).
25. P. von R. Schleyer, H. Jiao, Pure Appl. Chem. 1996, 68, 209-218.
26. a) W. Kutzelnigg, Isr. J. Chem. 1980, 19, 193-200;
27. b) M. Schindler, W. Kutzelnigg, J. Chem. Phys. 1982, 76, 1919-1933.
28. c) W. Kutzelnigg, U. Fleischer, M. Schindler, NMR Basic Princ. Prog. 1990, 23, 165-262.
29. A. Pasquarello, M. Schlüter, R. C. Haddon, Science 1992. 257, 1660-1661.
30. P. von R. Schleyer, C. Maerker, A. Dransfeld, H. Jiao, N. J. R. van E. Hommes. J. Am. Chem. Soc. 1996, 118, 6317-6318.
31. G. Subramanian, P. von R. Schleyer, H. Jiao, Angew. Chem. 1996, 108, 2824-2827, Angew. Chem. Int. Ed. Engl. 1996, 35, 2638-2641.
32. G. Subramanian, P. von R. Schleyer, H. Jiao, Angew. Chem. 1996, 108, 2824-2827, Angew. Chem. Int. Ed. Engl. 1996, 35, 2638-2641.