organic papers o3574 Duong et al.  C 32 H 26 Si doi:10.1107/S1600536806028169 Acta Cryst. (2006). E62, o3574–o3576 Acta Crystallographica Section E Structure Reports Online ISSN 1600-5368 cis-1,2,2,3-Tetraphenyl-2,3-dihydro-1H-2-benzosilole Luong C. Duong, Stephen K. Cope, Daniel S. Jones* and Craig A. Ogle Department of Chemistry, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, NC 28223, USA Correspondence e-mail: djones@email.uncc.edu Key indicators Single-crystal X-ray study T = 295 K Mean (C–C) = 0.003 A ˚ R factor = 0.035 wR factor = 0.101 Data-to-parameter ratio = 15.4 For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e. Received 24 May 2006 Accepted 20 July 2006 # 2006 International Union of Crystallography All rights reserved The title compound, C 32 H 26 Si, is a benzosilacyclopentene in which the silacyclopentene ring assumes an envelope confor- mation, with the Si atom displaced by 0.953 (2) A ˚ from the mean plane of the four C atoms. The Si atom is bonded to two phenyl rings and to two Csp 3 atoms in the silacyclopentene ring; one phenyl ring is attached to each of these two Csp 3 atoms in the cis configuration. Comment In the title compound, (3) (Fig. 1), the Si atom is bonded to two phenyl rings and to two Csp 3 atoms in the silacyclo- pentene ring; one phenyl ring is attached to each of these two Csp 3 atoms in the cis configuration. The average Si—phenyl bond distance is 1.869 (2) A ˚ . The average Si—Csp 3 bond distance is 1.902 (2) A ˚ , and the corresponding C—Si—C angle is 90.68 (7)  . The silacyclopentene ring assumes an envelope conformation, with the Si atom displaced by 0.953 (2) A ˚ from the mean plane of the four C atoms. The only structure in the Cambridge Structural Database (Version 5.27, ConQuest Version 1.8; Allen, 2002) having the same fused ring system as (3) is 2,2-diphenyl-2-silaindan (Vidal & Falgueirettes, 1973), which has H atoms on the silacyclopentene ring where (3) has phenyl rings. The Si— phenyl distances in 2,2-diphenyl-2-silaindan are nearly iden- tical, at 1.876 and 1.875 A ˚ . The average Si—Csp 3 distance is 1.886 A ˚ , and the corresponding C—Si—C angle is 93.59  . The silacyclopentene ring assumes an envelope conformation, with the Si atom displaced by 0.636 A ˚ from the mean plane of the four C atoms.