Closely Approaching the Silylium Ion (R 3 Si + )
- 15 October 1993
- journal article
- other
- Published by American Association for the Advancement of Science (AAAS) in Science
- Vol. 262 (5132) , 402-404
- https://doi.org/10.1126/science.262.5132.402
Abstract
The crystal structure of the tri-isopropyl silyl species, i-Pr3Si(Br6-CB11H6), where the brominated carborane Br6-CB11 H6– is perhaps the least nucleophilic anion presently known, has revealed the highest degree of silylium cation character (R3Si+) yet observed. The average C—Si—C angle is 117°, only 3° short of the planarity expected of a pure silylium ion(120°). This value compares to 114° recently reported for a toluene-solvated silyl cation, [Et3Si(toluene)]+ by Lambert and co-workers. The greater silylium ion character of i-Pr3Si(Br6-CB11H6) versus [i-Pr3Si(toluene)]+ is also reflected in the larger downfield shift of the silicon-29 nuclear magnetic resonance, 109.8 versus ≤94.0 parts per million. The unusual bonding of toluene to R3Si+ in Lambert's compound is reinterpreted as a significant covalent π interaction.Keywords
This publication has 9 references indexed in Scilit:
- A Fischer-type silylene complex of platinum: [trans-(Cy3P)2(H)Pt:Si(SEt)2]BPh4Journal of the American Chemical Society, 1993
- Crystal Structure of a Silyl Cation with No Coordination to Anion and Distant Coordination to SolventScience, 1993
- Stable silylnitrilium ionsJournal of the American Chemical Society, 1993
- Models for organometallic molecule-support complexes. Very large counterion modulation of cationic actinide alkyl reactivityOrganometallics, 1991
- Synthesis of [Ag2{.mu.-{{CH(COOR)}2PPh2}}2] (R = Me, Et). The first crystal structure of a dinuclear silver diylide complex (R = Et). One-pot synthesis of the phosphonium salts [Ph2P(CH2COOR)2]Cl (R = Me, Et)Organometallics, 1989
- Organometallic chemistry. 22. Triphenylsilyl perchlorate revisited: silicon-29 and chlorine-35 NMR spectroscopy and x-ray crystallography showing covalent nature in both solution and the solid state. Difficulties in observing long-lived silyl cations in the condensed stateJournal of the American Chemical Society, 1987
- .eta.1-Benzene coordination: the synthesis and x-ray crystal structure of a novel silver salt of the weakly coordinating carborane anion B11CH12-Journal of the American Chemical Society, 1985
- Microwave spectrum, structure, and chemical bonding of trimethylbromosilaneJournal of Molecular Spectroscopy, 1980
- Crystal structure of the tetrachloroaluminate salt of the heptamethylbenzene cationJournal of the American Chemical Society, 1968