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Title: Nido-Carborane building-block reagents. 4. Regiospecific substitution at born in 2,3-R/sub 2/C/sub 2/B/sub 4/H/sub 6/ cages. Evidence for intramolecular C-H---H/sub bridge/ interactions in 2,3-R/sub 2/C/sub 2/B/sub 4/H/sub 5/-4R' derivatives

Abstract

Reaction of nido-2,3-R/sub 2/C/sub 2/B/sub 4/H/sub 5//sup /minus// ions (R = ethyl, benzyl) with organic halides (R'X) generate B(4)-substituted derivatives together with the B(6)-substituted enantiomers. The formation of the R/sub 2/C/sub 2/B/sub 4/H/sub 5/-4-R' products (R' = Me, Et, CH/sub 2/Ph, CH/sub 2/C/sub 6/H/sub 4/Me) is proposed to occur via R/sub 2/C/sub 2/B/sub 4/H/sub 5/-/mu/(4,5)-R' bridged bridged intermediates, which rapidly rearrange to the 4-substituted species. The reaction occurs cleanly, with /le/ 1% contamination by other geometric isomers, and thus furnishes a useful regiospecific synthetic route to B-monosubstituted derivatives. In all cases examined, the products are air-stable liquids of low volatility that can be employed as building-block units in the synthesis of organometallic complexes and oligomers. Proton NMR spectra of several of the 2,3,4-trisubstituted products, supported by NOE experiments, indicate spin coupling between a C-CH/sub 2/ methylene proton and a B-H-B bridging hydrogen. The triethyl and tribenzyl derivatives were bridge-deprotonated by NaH, complexed to Fe/sup 2+/, and oxidatively fused to produce the hexasubstituted R/sub 6/C/sub 4/B/sub 8/H/sub 6/ carboranes, although the reaction was sluggish compared to those of the parent C,C/prime/-disubstituted carboranes. The fused compounds are nonfluxional in solution, as determined from NMR spectra. 22 refs., 5 figs., 3 tabs.

Authors:
;
Publication Date:
Research Org.:
Univ. of Virginia, Charlottesville (USA)
OSTI Identifier:
5852722
Resource Type:
Journal Article
Journal Name:
Inorg. Chem.; (United States)
Additional Journal Information:
Journal Volume: 27:23
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CARBORANES; CHEMICAL REACTIONS; BORON 11; EXPERIMENTAL DATA; NMR SPECTRA; PROTONS; BARYONS; BORON COMPOUNDS; BORON ISOTOPES; CARBON COMPOUNDS; DATA; ELEMENTARY PARTICLES; FERMIONS; HADRONS; INFORMATION; ISOTOPES; LIGHT NUCLEI; NUCLEI; NUCLEONS; NUMERICAL DATA; ODD-EVEN NUCLEI; SPECTRA; STABLE ISOTOPES; 400201* - Chemical & Physicochemical Properties; 400202 - Isotope Effects, Isotope Exchange, & Isotope Separation

Citation Formats

Davis, Jr, J H, and Grimes, R N. Nido-Carborane building-block reagents. 4. Regiospecific substitution at born in 2,3-R/sub 2/C/sub 2/B/sub 4/H/sub 6/ cages. Evidence for intramolecular C-H---H/sub bridge/ interactions in 2,3-R/sub 2/C/sub 2/B/sub 4/H/sub 5/-4R' derivatives. United States: N. p., 1988. Web. doi:10.1021/ic00296a024.
Davis, Jr, J H, & Grimes, R N. Nido-Carborane building-block reagents. 4. Regiospecific substitution at born in 2,3-R/sub 2/C/sub 2/B/sub 4/H/sub 6/ cages. Evidence for intramolecular C-H---H/sub bridge/ interactions in 2,3-R/sub 2/C/sub 2/B/sub 4/H/sub 5/-4R' derivatives. United States. doi:10.1021/ic00296a024.
Davis, Jr, J H, and Grimes, R N. Wed . "Nido-Carborane building-block reagents. 4. Regiospecific substitution at born in 2,3-R/sub 2/C/sub 2/B/sub 4/H/sub 6/ cages. Evidence for intramolecular C-H---H/sub bridge/ interactions in 2,3-R/sub 2/C/sub 2/B/sub 4/H/sub 5/-4R' derivatives". United States. doi:10.1021/ic00296a024.
@article{osti_5852722,
title = {Nido-Carborane building-block reagents. 4. Regiospecific substitution at born in 2,3-R/sub 2/C/sub 2/B/sub 4/H/sub 6/ cages. Evidence for intramolecular C-H---H/sub bridge/ interactions in 2,3-R/sub 2/C/sub 2/B/sub 4/H/sub 5/-4R' derivatives},
author = {Davis, Jr, J H and Grimes, R N},
abstractNote = {Reaction of nido-2,3-R/sub 2/C/sub 2/B/sub 4/H/sub 5//sup /minus// ions (R = ethyl, benzyl) with organic halides (R'X) generate B(4)-substituted derivatives together with the B(6)-substituted enantiomers. The formation of the R/sub 2/C/sub 2/B/sub 4/H/sub 5/-4-R' products (R' = Me, Et, CH/sub 2/Ph, CH/sub 2/C/sub 6/H/sub 4/Me) is proposed to occur via R/sub 2/C/sub 2/B/sub 4/H/sub 5/-/mu/(4,5)-R' bridged bridged intermediates, which rapidly rearrange to the 4-substituted species. The reaction occurs cleanly, with /le/ 1% contamination by other geometric isomers, and thus furnishes a useful regiospecific synthetic route to B-monosubstituted derivatives. In all cases examined, the products are air-stable liquids of low volatility that can be employed as building-block units in the synthesis of organometallic complexes and oligomers. Proton NMR spectra of several of the 2,3,4-trisubstituted products, supported by NOE experiments, indicate spin coupling between a C-CH/sub 2/ methylene proton and a B-H-B bridging hydrogen. The triethyl and tribenzyl derivatives were bridge-deprotonated by NaH, complexed to Fe/sup 2+/, and oxidatively fused to produce the hexasubstituted R/sub 6/C/sub 4/B/sub 8/H/sub 6/ carboranes, although the reaction was sluggish compared to those of the parent C,C/prime/-disubstituted carboranes. The fused compounds are nonfluxional in solution, as determined from NMR spectra. 22 refs., 5 figs., 3 tabs.},
doi = {10.1021/ic00296a024},
journal = {Inorg. Chem.; (United States)},
number = ,
volume = 27:23,
place = {United States},
year = {1988},
month = {11}
}