Allyl‐End‐Grafted Carbosilane Dendrimers Based on 1, 4‐Phenylene Units: Synthesis, Reactivity, Structure, and Bonding Motifs12. Issue 13 (28th February 2013)

• Record Type: Journal Article
• Authors: Ishtaiwi, Zakariyya; Rüffer, Tobias; Hildebrandt, Alexander; Awwadi, Firas F.; Hahn, Harald; Abylaikhan, Akerke; Taher, Deeb; Siegert, Uwe; Walfort, Bernhard; Lang, Heinrich
• Is Part Of: European journal of inorganic chemistry. Issue 13(2013)
• Page Start: 2368
• Page End: 2381
• Publication Date: 2013-02-28
• Subjects: Dendrimers -- Self‐assembly -- Supramolecular chemistry -- Pi interactions -- NMR spectroscopy; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201201428
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract: The synthesis of a series of carbosilanes of type 1‐Br–C6 H4 –4‐SiMe3– n (CH2 CH=CH2 ) n ( n = 1, 2, 3), Si[C6 H4 –4‐SiMe3– n (CH2 CH=CH2 ) n ]4, 1‐Br–C6 H4 ‐4‐Si[C6 H4 –4‐SiMe3– n (CH2 CH=CH2 ) n ]3 ( n = 0, 1, 2, 3), ClSi[C6 H4 –4‐Si{C6 H4 –4‐SiMe3– n (CH2 CH=CH2 ) n }3 ]3, Si[C6 H4 –4‐Si{C6 H4 –4‐SiMe3– n (CH2 CH=CH2 ) n }3 ]4 ( n = 1, 2), and 1‐Br–C6 H4 –4‐Si[C6 H4 –4‐Si{C6 H4 –4‐SiMe3– n (CH2 CH=CH2 ) n }3 ]3 ( n = 0, 1, 2, 3) is discussed. The structures of Si[C6 H4 –4‐SiMe2 (CH2 CH=CH2 )]4 (7b ) and ClSi[C6 H4 –4‐Si{C6 H4 –4‐SiMe2 (CH2 CH=CH2 )}3 ]3 (10a ) in the solid state are reported. The crystal structures of both dendrimers are based on C–H··· πCC (πCC = double bond of the CH=CH2 groups) and π–π interactions. The 3D network structure observed for7b is composed of three crystallographically independent head‐to‐head stacking columns along the crystallographic b axis with π–π contacts among the C6 H4 groups of neighboring molecules, with the columns interacting further by C–H··· πCC arrangements. Two molecules of10a interdigitate in the solid state to form self‐complementary dimers that are stabilized by C–H··· πCC and π–π contacts. The structures of the monomer and the dimer were optimized by using the MM + force field as implemented in HyperChem 4.0 2 . In addition, the presence of self‐complementary structures in solution is evidenced from 1 H NMR spectroscopy. In dichloromethane solely dimeric species exist, whereas in benzene monomers are observed. Calculated electrostatic potentials were used to rationalize the supramolecular structures of these two carbosilane compounds. Abstract : The synthesis of zeroth‐ and first‐generation carbosilane dendrimers with rigid 1, 4‐phenylene units is reported. The first‐generation dendrimers undergo dimerization due to π–π interactions between the C6 H4 units, which stack in a T‐shaped conformation as evidenced by X‐ray structural determination, molecular mechanics calculations, and NMR spectroscopy.