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A Very Brief Introduction to Boron Chemistry

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A Very Brief Introduction to Boron Chemistry Kristina Orosz Nov. 5, 2004 Uses of Boron Borosilicate glass-pyrex Detergents Flame retardants Ceramics Pyrotechnics Used ... – PowerPoint PPT presentation

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Title: A Very Brief Introduction to Boron Chemistry


1
A Very Brief Introduction to Boron Chemistry
  • Kristina Orosz
  • Nov. 5, 2004

2
Uses of Boron
  • Borosilicate glass-pyrex
  • Detergents
  • Flame retardants
  • Ceramics
  • Pyrotechnics
  • Used in production of impact resistant steels
  • Control rods in nuclear reactors

3
Common Bonds in Boranes
  • 2c-2e- B-H
  • 3c-2e- B-H-B
  • 2c-2e- B-B
  • 3c-2e- B-B-B

4
Diborane B2H6
5
  • B2H6 MO Diagram

Wade, K. Electron Deficient Compounds. London
Nelson, 1971. 30.
6
Tetraborane B4H10
7
  • Dodecaborane B12H122-

Huheey, J. E. Keiter, E. A. Keiter, R. L.
Inorganic Chemistry principles of structure and
reactivity, 4th ed. New York HarperCollins
College Publisher, 1993. 795.
8
Elemental Forms of Boron
b-rhombohedral, B12(B12)12, (B12)(B12)(B60)
a- rhombohdral
9
Boron Deltahedra Parent Clusters
10
Boron Hydrides
11
Huheey, J. E. Keiter, E. A. Keiter, R. L.
Inorganic Chemistry principles of structure and
reactivity, 4th ed. New York HarperCollins
College Publishing, 1993. 799.
12
Wades Rules
  • n number of B atoms in parent closo-deltahedron
  • Always n1 bonding e- pairs and n1 bonding MOs
  • nido has n-1 vertices
  • arachno has n-2 vertices
  • hypho has n-3 vertices

13
  • Find total available bonding e-s
  • Each B-H unit gives 2 e-s
  • Each additional H gives 1 e-
  • Overall charge
  • Find parent closo-deltahedron
  • n1 bonding e- pairs
  • Is it closo, nido, arachno, hypho?
  • Lose highest connectivity B first then lose
    adjacent sites
  • Determine number of remaining hydrogen atoms
  • Each vertex has a H
  • sew up hole with H atoms
  • Bridging H atoms
  • Low connectivity B atoms can get another 2c-2e-
    B-H bond
  • Try to keep it as symmetrical as possible
  • Using Wades Rules

14
(No Transcript)
15
CarboranesC2B10H12
ortho
meta or neo
para
16
Boron Neutron Capture Therapy (BNCT)
  • 10B has large cross-section for neutron capture
  • 10B ? a 7Li
  • Products can kill cells
  • Cancer treatment
  • Cages - need high 10B in cell

17
References
  • Dreiss, Matthias, ed., and Heinrich Nöth, ed.
    Molecular Clusters of the Main Group Elements.
    Weinheim Wiley-VCH, 2004. 95-125.
  • Housecroft, Catherine E. Boranes and
    Metallaboranes structure, bonding, and
    reactivity. 2nd ed. New York Ellis Horwood,
    1994. 1-20, 93-116.
  • Housecroft, Catherine E., and Alan G. Sharpe.
    Inorganic Chemistry. New York Pearson Education
    Limited, 2001. 245-279.
  • Huheey, James E., Ellen A. Keiter, and Richard L.
    Keiter. Inorganic Chemistry principles of
    structure and reactivity. New York HarperCollins
    College Publishers, 1993. 789-801.
  • Wade, Kenneth. Electron Deficient Compounds.
    London Nelson, 1971. 1-61.
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