Lewis Acid/Base Interaction Matrix Database
Type 1 complexes, typified by hydrogen H2, are covalently bonded. The bonding is frontier molecular orbital (FMO) controlled. Hydrogen, H2, has a 1σ2 MO structure, ie they have two electrons in their 1σ molecular orbital.
Find out more about the bonding diatomic species elsewhere in this webbook, here.
|Charge:||Complexes can be neutral, H2, or positively charged [H3]+.|
Protons complex with hydride ions to form molecular hydrogen, H2, a uniquely simple and much studied diatomic molecule.
The H+ + H– → H2 reaction is not reversible: H2 does not act as a proton donor (although at high temperature, when exposed to high energy UV radiation or when absorbed onto a metallic surface, H2 can homolytically dissociate: radical cleavage).
As protons and hydride ions do not exist as independent species, they require "delivery" by donor complexes, ie reagents. Protons, H+ ions, are supplied by Brønsted acids and hydride ions by hydride donor complexes.
For example, hydrogen chloride an H+ donor reacts with sodium hydride an H– donor to give diatomic hydrogen and sodium chloride:
HCl + NaH → H2 + NaCl
[H3]+, the product of H+ and H2, is the simplest possible triatomic molecular ion – it has only two electrons – and is of considerable theoretical interest.
(In this author's opinion the [H3]+ ion should be called the 'hydronium ion', and [OH3]+ should be the 'oxonium ion'.)
|Congeneric Series:||Few series.|
|Type 1 Lewis acid/base complex (generic)
|Hydronium ion, [H3]+
|Interactions and reactions classified as:|
|Poster||Nucleophiles & Bases|
© Mark R. Leach 1999 –
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