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A Very Brief Introduction to Boron Chemistry

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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 Huheey, J. E.; Keiter, E. A.; Keiter, R. L. Inorganic Chemistry: principles of structure and reactivity, 4th ed. New York: HarperCollins College Publisher,

5 B2H6 MO Diagram Wade, K. Electron Deficient Compounds. London: Nelson,

6 Tetraborane B4H10 Huheey, J. E.; Keiter, E. A.; Keiter, R. L. Inorganic Chemistry: principles of structure and reactivity, 4th ed. New York: HarperCollins College Publisher,

7 Dodecaborane [B12H12]2- Huheey, J. E.; Keiter, E. A.; Keiter, R. L. Inorganic Chemistry: principles of structure and reactivity, 4th ed. New York: HarperCollins College Publisher,

8 Elemental Forms of Boron
b-rhombohedral, B12(B12)12, (B12)(B12)(B60) a- rhombohdral Housecroft, C. E.; Sharpe, A. G. inorganic Chemistry. New York: Pearson Education Limited,

9 Boron Deltahedra – Parent Clusters
Housecroft, C. E.; Sharpe, A. G. inorganic Chemistry. New York: Pearson Education Limited,

10 Boron Hydrides Housecroft, C. E.; Sharpe, A. G. inorganic Chemistry. New York: Pearson Education Limited,

11 Huheey, J. E. ; Keiter, E. A. ; Keiter, R. L
Huheey, J. E.; Keiter, E. A.; Keiter, R. L. Inorganic Chemistry: principles of structure and reactivity, 4th ed. New York: HarperCollins College Publishing,

12 Wade’s Rules n = number of B atoms in parent closo-deltahedron
Always n+1 bonding e- pairs and n+1 bonding MOs nido has n-1 vertices arachno has n-2 vertices hypho has n-3 vertices

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

14 Huheey, J. E. ; Keiter, E. A. ; Keiter, R. L
Huheey, J. E.; Keiter, E. A.; Keiter, R. L. Inorganic Chemistry: principles of structure and reactivity, 4th ed. New York: HarperCollins College Publisher,

15 Carboranes C2B10H12 ortho meta or neo para
Huheey, J. E.; Keiter, E. A.; Keiter, R. L. Inorganic Chemistry: principles of structure and reactivity, 4th ed. New York: HarperCollins College Publisher,

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, Housecroft, Catherine E. Boranes and Metallaboranes: structure, bonding, and reactivity. 2nd ed. New York: Ellis Horwood, , Housecroft, Catherine E., and Alan G. Sharpe. Inorganic Chemistry. New York: Pearson Education Limited, Huheey, James E., Ellen A. Keiter, and Richard L. Keiter. Inorganic Chemistry: principles of structure and reactivity. New York: HarperCollins College Publishers, Wade, Kenneth. Electron Deficient Compounds. London: Nelson,


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