Page 116 - Arrow Pushing in Inorganic Chemistry A Logical Approach to the Chemistry of the Main Group Elements

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Group 14 Elements

… sticky messes with no particular use …
Frederic Stanley Kipping, referring to his
newly discovered silicones, Proc. Chem.
Soc. 1905, 21, 65–66.

Since the few [organosilicon compounds]
which are known are very limited in their
reactions, the prospect of any immediate and
important advances in this section of organic
chemistry does not seem very hopeful.
Frederic Stanley Kipping, Bakerian lecture of the Royal Society, 1936
Our focus in this chapter is on group 14 elements other than carbon, namely, silicon, ger-
manium, tin, and lead. As in the case of group 13, the properties change considerably as we
go down the group, with the greatest discontinuity between carbon and silicon. Thus, car-
bon is a quintessential nonmetal, whereas silicon and germanium are semiconductors and
tin and lead are metals. Compared with the s-block elements, both Sn and Pb are far less
electropositive; unsurprisingly, therefore, all group 14 elements have an extensive covalent
chemistry. The following are a few important group trends:
• The standard group valence is 4. For Si, Ge, and Sn, however, coordination numbers
exceeding 4 occur regularly. The central atoms in such species are thus hypervalent,
that is, they have more than an octet of valence electrons. For example, 2,2-bipyridyl
reacts with triphenylchlorosilane to yield a relatively stable pentacoordinate silicon
complex. Observe that, although the Si carries a −1 formal charge, the complex as a
whole is cationic:

Arrow Pushing in Inorganic Chemistry: A Logical Approach to the Chemistry of the Main-Group Elements,
First Edition. Abhik Ghosh and Steffen Berg.
© 2014 John Wiley & Sons, Inc. Published 2014 by John Wiley & Sons, Inc.

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