The molecular structure of pentaborane(9) with halogen substituents in apical and basal positions, determined by electron diffraction and theoretical calculations

R. Greatrex, C. Workman, B. Johnston, D.W.H. Rankin, H.E. Robertson

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

The molecular structures of 1-bromo–pentaborane(9) and 2-bromo–pentaborane(9) in the gas phase have been determined by electron diffraction and ab initio and DFT computational methods. Computational methods have also been applied to the fluoro and chloro analogues, to 1,2-dibromo-pentaborane(9), and to the parent unsubstituted borane. The electronic effects of halogen substitution on the borane cage are remarkably small, particularly for chlorine and bromine substituents, and steric effects are also minimal, even in the compound with two bromine atoms. The largest effects are (a) lengthening of B(base)–B(apex) bonds adjacent to the halogen in the 2-isomers, with an associated shortening of the opposite base–apex bond, (b) shortening of the B(base)–B(apex) bond in the 1-fluoro compound, and (c) increase of the B(base)–B(apex)–F angle in 1-F–B5H8, but a decrease in this angle in the 2-bromo compounds.
LanguageEnglish
Pages1719-1725
Number of pages7
JournalDalton Transactions
Volume11
DOIs
Publication statusPublished - 2004

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Halogens
Electron diffraction
Boranes
Molecular structure
Bromine
Computational methods
Chlorine
Discrete Fourier transforms
Isomers
Substitution reactions
Gases
Atoms
pentaborane

Keywords

  • pentaborane
  • halogen substituents
  • electron diffraction

Cite this

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title = "The molecular structure of pentaborane(9) with halogen substituents in apical and basal positions, determined by electron diffraction and theoretical calculations",
abstract = "The molecular structures of 1-bromo–pentaborane(9) and 2-bromo–pentaborane(9) in the gas phase have been determined by electron diffraction and ab initio and DFT computational methods. Computational methods have also been applied to the fluoro and chloro analogues, to 1,2-dibromo-pentaborane(9), and to the parent unsubstituted borane. The electronic effects of halogen substitution on the borane cage are remarkably small, particularly for chlorine and bromine substituents, and steric effects are also minimal, even in the compound with two bromine atoms. The largest effects are (a) lengthening of B(base)–B(apex) bonds adjacent to the halogen in the 2-isomers, with an associated shortening of the opposite base–apex bond, (b) shortening of the B(base)–B(apex) bond in the 1-fluoro compound, and (c) increase of the B(base)–B(apex)–F angle in 1-F–B5H8, but a decrease in this angle in the 2-bromo compounds.",
keywords = "pentaborane , halogen substituents , electron diffraction",
author = "R. Greatrex and C. Workman and B. Johnston and D.W.H. Rankin and H.E. Robertson",
year = "2004",
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The molecular structure of pentaborane(9) with halogen substituents in apical and basal positions, determined by electron diffraction and theoretical calculations. / Greatrex, R.; Workman, C.; Johnston, B.; Rankin, D.W.H.; Robertson, H.E.

In: Dalton Transactions, Vol. 11, 2004, p. 1719-1725.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The molecular structure of pentaborane(9) with halogen substituents in apical and basal positions, determined by electron diffraction and theoretical calculations

AU - Greatrex, R.

AU - Workman, C.

AU - Johnston, B.

AU - Rankin, D.W.H.

AU - Robertson, H.E.

PY - 2004

Y1 - 2004

N2 - The molecular structures of 1-bromo–pentaborane(9) and 2-bromo–pentaborane(9) in the gas phase have been determined by electron diffraction and ab initio and DFT computational methods. Computational methods have also been applied to the fluoro and chloro analogues, to 1,2-dibromo-pentaborane(9), and to the parent unsubstituted borane. The electronic effects of halogen substitution on the borane cage are remarkably small, particularly for chlorine and bromine substituents, and steric effects are also minimal, even in the compound with two bromine atoms. The largest effects are (a) lengthening of B(base)–B(apex) bonds adjacent to the halogen in the 2-isomers, with an associated shortening of the opposite base–apex bond, (b) shortening of the B(base)–B(apex) bond in the 1-fluoro compound, and (c) increase of the B(base)–B(apex)–F angle in 1-F–B5H8, but a decrease in this angle in the 2-bromo compounds.

AB - The molecular structures of 1-bromo–pentaborane(9) and 2-bromo–pentaborane(9) in the gas phase have been determined by electron diffraction and ab initio and DFT computational methods. Computational methods have also been applied to the fluoro and chloro analogues, to 1,2-dibromo-pentaborane(9), and to the parent unsubstituted borane. The electronic effects of halogen substitution on the borane cage are remarkably small, particularly for chlorine and bromine substituents, and steric effects are also minimal, even in the compound with two bromine atoms. The largest effects are (a) lengthening of B(base)–B(apex) bonds adjacent to the halogen in the 2-isomers, with an associated shortening of the opposite base–apex bond, (b) shortening of the B(base)–B(apex) bond in the 1-fluoro compound, and (c) increase of the B(base)–B(apex)–F angle in 1-F–B5H8, but a decrease in this angle in the 2-bromo compounds.

KW - pentaborane

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U2 - 10.1039/b402688h

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