1,4-Bis[4-(tert-butyldiphenylsilyl)buta-1,3-diynyl]benzene

The title centrosymmetric molecule, C46H42Si2, is composed of a central benzene ring with buta-1,3-diynyl chains at positions 1 and 4. These chains are terminated by tert-butyldiphenylsilyl groups, hence the molecule is dumbbell in shape. The molecules are connected via C—H⋯π interactions in the structure, so forming an undulating two-dimensional network in the bc plane. There is also a weak π–π interaction involving centrosymmetrically related phenyl rings with a centroid–centroid distance of 3.8359 (11) Å.

The title centrosymmetric molecule, C 46 H 42 Si 2 , is composed of a central benzene ring with buta-1,3-diynyl chains at positions 1 and 4. These chains are terminated by tert-butyldiphenylsilyl groups, hence the molecule is dumbbell in shape. The molecules are connected via C-HÁ Á Á interactions in the structure, so forming an undulating two-dimensional network in the bc plane. There is also a weakinteraction involving centrosymmetrically related phenyl rings with a centroidcentroid distance of 3.8359 (11) Å .

Comment
The unique properties of polyynes and acetylenic arrays continue to be of great interest (Ginsburg et al., 1995;Siemsen et al., 2000;Brandsma, 1988). Compounds containing conjugated carbon-carbon triple bonds are important building blocks because they can function as carbon-rich scaffolds when incorporated into organic materials (Swager, 2005;Tobe & Wakabayashi, 2005;Höger, 2005;Zhou et al., 1994). Consequently, research into the synthesis of well-defined polyynes continues to expand. The efficiency of the energy and electron transfer processes in polyyne-bridged porphyrin systems (Maruyama & Kawabata, 1990) and bis(benzocrown ether)s (Lee et al., 2000) have been examined for their potential use as molecular wires and chemosensors.
The title compound was designed as a spacer-unit in linked materials for the creation of structured, discotic mesophases. It was synthesized from tert-Butyl(4,4-dibromobut-3-en-1-ynyl)diphenylsilane using a "one-pot" tandem synthesis, consisting of a Corey-Fuchs reaction (Corey & Fuchs, 1972;Desai & McKelvie, 1962) and a Negishi coupling reaction (King et al., 1977). The synthesis and crystal structure of the trimethylsilyl analogue has been described by (Shi Shun et al., 2003), and for some other related compounds by Chalifoux et al., 2009;Kim, 2009;West et al. (2008).
The title molecule is shown in Fig. 1. The bond lengths are normal (Allen et al., 1987) and the geometrical parameters are similar to those in the centrosymmetric trimethylsilyl analogue mentioned above (Shi Shun et al., 2003). The title molecule consists of a central benzene ring to which are attached buta-1,3-diynyl chains in positions 1 and 4. These chains are terminated with tert-butyldiphenylsilyl groups. The molecule is essentially linear and shaped like a dumbbell. The centers of the benzene rings are situated on crystallographic centers of symmetry, therefore the molecule has symmetry 1.
In the crystal of the title compound symmetry related molecules are connected via C-H···π interactions, involving the H-atoms of the central aromatic ring and the silyl phenyl rings, giving rise to the formation of an undulating two-dimensional network in the bc plane (Tab. 1 and Fig. 2). Centrosymmetrically related phenyl rings (C14 -C19), are involved in a weak π-π interaction with a centroid-to-centroid distance [Cg1···Cg1 i , symmetry code: (i) = 1-x, 1-y, 1-z] of 3.836 (1) Å.