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316 Boron Hydrides

FIGURE 19 A metal complex containing two olide ions and two metal atoms enclosing a canistide ion. [From Dunks,
G. B., and Hawthorne, M. F. (1975). In “Boron Hydride Chemistry” (E. L. Muetterties, ed.), p. 405, Academic Press,
New York, Figure 11.25.]

that are prevalent in living tissue is given in Table IV. The ticularly relevant to this article are derivatives of the
other elements in this table will also emit ionizing radia- closo boron hydride anions, B 12 H 2− and B 10 H 2− con-
12 10
tion when neutrons are absorbed, but the much higher neu- taining the sulfhydryl group ( SH), which can bind to
tron cross section of boron means that the radiation will proteins.
be dominant in the boron-containing regions provided that Problems of binding boron-containing compounds to
the concentration of boron is sufficiently high compared tumorous tissue as well as delivering the slow-moving
to that of the other elements. neutrons to the desired region have yet to be perfected.
Research in the area of BNCT has been directed to- However, vigorous research continues in this area, and
ward developing methods for delivering boron-containing commercial ventures have been initiated.
compounds to tumorous tissue and avoiding the surround-
ing healthy tissue. A number of different strategies have
been employed including boron-containing derivatives of SEE ALSO THE FOLLOWING ARTICLES
proteins, nucleosides, porphyrins, and antibodies. Par-
HYDROGEN BONDS • METAL HYDRIDES

TABLE IV Thermal Neutron Cross Sections of
10 B (barns) Compared with Isotopes of Other BIBLIOGRAPHY
Elements
Isotope Thermal neutron Cross section Beall, H., and Gaines, D. F. (1999). “Chemistry of Pentaborane(9).
A Review.” Collect. Czech. Chem. Commun. 64, 747–765.
10 B 3838 Beall, H., and Gaines, D. F. (1999). “Mechanistic Aspects of Boron
Hydride Reactions.” Inorgan. Chem. Acta 1–10.
16 O 0.0002
Hawthorne, M. F. (1991) “Biochemical Applications of Boron Cluster
12 C 0.0037 Chemistry,” Pure Appl. Chem. 63, 327–334.
1 H 0.332 Siebert, W., ed. (1997). “Advances in Boron Chemistry,” Royal Society
14 N 1.75 of Chemistry, Cambridge.
Soloway, A. H., Tjarks, W., Barnum, B. A., Rong, F., Barth, R. F.,
[From Barth, R. R., Soloway, A. H., and Fairchild, Codogni, I. M., and Wilson, J. G. (1998). “The Chemistry of Neu-
R. G. (1990). Scie. Ame. 100–107.] tron Capture Tumor Therapy.” Chem. Rev. 98, 1515–1562.