Dibenzopentalene (dibenzo[a,e]pentalene or dibenzo[b,f]pentalene) is an organic compound and a hydrocarbon with formula C16H10. It is of some scientific interest as a stable derivative of the highly reactive antiaromatic pentalene by benzannulation.[1] The first derivative was synthesised in 1912 by Brand.[2] The parent compound was reported in 1952.[3] The NICS value for the 5-membered rings is estimated at 7.4 ppm and that of the six-membered rings -9.8 ppm.[1] Aromatic dicationic salts can be obtained by reaction with antimony pentafluoride in sulfuryl chloride. The dianion forms by reduction with lithium metal or deprotonation of 5,10-dihydroindeno[2,1-a]indene with two equivalents of butyllithium.[4][5] The aromatic nature of the dianion has been confirmed by X-ray analysis.[6] Another isomer of this compound exists called dibenzo[a,f]pentalene with one of the benzene rings positioned on the other available pentalene face.

Dibenzopentalene
Names
Preferred IUPAC name
Indeno[2,1-a]indene
Identifiers
3D model (JSmol)
ChemSpider
UNII
  • InChI=1S/C16H10/c1-3-7-13-11(5-1)9-15-14-8-4-2-6-12(14)10-16(13)15/h1-10H
    Key: OZEPXROCWSMGGM-UHFFFAOYSA-N
  • C1=C2C(=CC3=C2C=CC=C3)C2=CC=CC=C12
Properties
C16H10
Molar mass 202.256 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

References

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  1. ^ a b Saito, Masaichi (2010). "Synthesis and Reactions of Dibenzo\a,e]pentalenes". Symmetry. 2 (2): 950–969. Bibcode:2010Symm....2..950S. doi:10.3390/sym2020950.
  2. ^ Brand, K. Über Gefärbte Kohlenwasserstoffe der Diphensuccinden-Reihe. Ber. Detsch. Chem. Ges. 1912, 45, 3071-3077
  3. ^ Blood, C. T.; Linstead, R. P. (1952). "422. Fused carbon rings. Part XXI. Dibenzopentalene". Journal of the Chemical Society (Resumed): 2263. doi:10.1039/JR9520002263.
  4. ^ Willner, Itamar; Rabinovitz, Mordecai (1978). "1,9-Dimethyldibenzo\b,f]pentalene dication and dianion. New 14.pi. And 18.pi. Aromatic systems". Journal of the American Chemical Society. 100: 337–338. doi:10.1021/ja00469a085.
  5. ^ Willner, Itamar; Becker, James Y.; Rabinovitz, Mordecai (1979). "Manifestation of dual aromaticity in doubly charged annelated pentalenes". Journal of the American Chemical Society. 101 (2): 395. doi:10.1021/ja00496a020.
  6. ^ Saito, Masaichi; Nakamura, Michio; Tajima, Tomoyuki; Yoshioka, Michikazu (2007). "Reduction of Phenyl Silyl Acetylenes with Lithium: Unexpected Formation of a Dilithium Dibenzopentalenide". Angewandte Chemie International Edition. 46 (9): 1504–7. doi:10.1002/anie.200604067. PMID 17387657.