Page 21 - Arrow Pushing in Inorganic Chemistry A Logical Approach to the Chemistry of the Main Group Elements

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A Collection of Basic

Concepts

In solving a problem of this sort, the grand
thing is to be able to reason backward. That is
a very useful accomplishment, and a very easy
one, but people do not practise it much. In the
everyday affairs of life it is more useful to reason
forward, and so the other comes to be neglected.
Sherlock Holmes in A Study in Scarlet, By Sir Arthur Conan Doyle

We assume you’ve had an introductory course in organic chemistry and hope you found
it logical and enjoyable. The logic of organic chemistry is of course key to its charm, and
mechanisms are a big part of that logic. In this book, we will present a similar approach
for inorganic chemistry, focusing on the main-group elements, that is, the s and p blocks
of the periodic table (Figure 1.1). As in organic chemistry, our main tool will be the curly
arrows that indicate the movement of electrons, typically electron pairs, but on occasion
also unpaired electrons. As we shall see, this approach—arrow pushing—works well in
inorganic chemistry, especially for the main-group elements.
We want to get you started with arrow pushing in an inorganic context as quickly as
possible, but we’d also like to make sure that you are equipped with the necessary concep-
tual tools. In this chapter, we’ll try to provide you with that background as efficiently as
possible. Unavoidably, the concepts form a somewhat disparate bunch but they do follow a
certain logic. Sections 1.1–1.6 introduce the idea of nucleophiles and electrophiles, in the
context of the S 2 displacement, and discuss physical concepts such as electronegativity,
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polarizability, pK , redox potentials, and bond energies in relation to chemical reactivity.
a
Armed with these concepts, we’ll devote the next several Sections 1.7–1.21 to survey key
mechanistic paradigms, focusing on major organic reaction types but also on a few special
inorganic ones. Sections 1.22 and 1.23 then present practical tips on arrow pushing, that

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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