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Strukturen und Moleküleigenschaften sterisch überfüllter Moleküle, 36. ( E )‐1,1,1,4,4,4‐Hexakis(trimethylsilyl)‐2‐buten [(H 3 C) 3 Si] 3 C—HCCH—C[Si(CH 3 ) 3 ] 3 und Bis[tris(trimethylsilyl)silyl]ethin [(H 3 C) 3 Si] 3 Si—C≡C—Si[Si(CH 3 ) 3 ] 3
Author(s) -
Bock Hans,
Meuret Jochen,
Schödel Holger
Publication year - 1993
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19931261010
Subject(s) - trimethylsilyl , chemistry , steric effects , substituent , ethylene , crystallography , silylation , molecule , stereochemistry , crystal structure , derivative (finance) , medicinal chemistry , organic chemistry , catalysis , financial economics , economics
Structures and Molecular Properties of Sterically Overcrowded Molecules, 36 [1] . — ( E )‐1,1,1,4,4,4‐Hexakis(trimethylsilyl)‐2‐butene [(H 3 C) 3 Si] 3 C—HCCH—C[Si(CH 3 ) 3 ] 3 and Bis[tris(trimethylsilyl)silyl]ethin [(H 3 C) 3 Si] 3 Si—C≡C—Si[Si(CH 3 ) 3 ] 3 The single crystal structure of an ethylene derivative, in which the two substituent half‐shells are separated by a CC spacer of about 403 pm length, shows C≡C distances of 404, 415 as well as 421 pm between non‐adjacent and of 352 pm between adjacent methyl groups, i.e. close to or within their van der Waals radii sum of 400 pm. The PE‐spectroscopically determined vertical first ionization energies of both compounds, 7.78 eV and 7.71 eV, are each the lowest ones reported so far for disubstituted ethylenes and acetylenes. Despite of irreversible cyclovoltammetric oxidation potentials, the radical cation of the six‐fold R 3 Si‐substituted 2‐butene can be generated by SbCl 5 /H 2 CCl 2 and characterized below 230 K by its ESR spectrum.