CHAPTER V.
COMPOUNDS CONTAINING A COMPLEX POSITIVE
COMPONENT.THE fundamental principles involved in the formation and dissociation of
compounds containing complex cations are essentially the same as in com-
pounds with complex anions. For example, hexamminenickelous bromide
is formed as represented by the equation:
NiBr 2 + 6 NH, = [Ni(NH 3 ) 6 ] Bra;hexaaquochromic chloride:
CrCl 3 + 6 H 2 O = [Cr(H 2 O) 6 ] Cl 3 ;ammonium chloride is formed either in a similar manner:
NH 3 + HC1 - [NH 3 .H]C1;or by the association of the ions:
NH 4 + + Cl- = NH 4 C1.The last two equations, viewed in the light of Werner's theory of secondary
valences (cf. page 141), lead to the following structural formula:
H—N-H- -Cl.
H^ J
Compounds with complex cations dissociate according to reactions which
are the raverse of the reactions of their formation; naturally both formation
and dissociation may take place in stages.
In the production of complex cations, ammonia and water come most
frequently into consideration. Among the ammonia compounds, those in
which ammonia, or a substituted ammonia, is joined to hydrogen (ammonium
or substituted ammonium compounds) are to be distinguished from those
in which ammonia, or a substituted ammonia, is joined to metal. The classi-
fication which follows is based upon this distinction.
Other complex-producing substances than those mentioned are less often
met with. As representative of the compounds which they form, the nitric-
oxide-metal compounds (cf. the well-known test for nitric acid with ferrous
sulphate) may be mentioned, as well as the addition products with alcohol,
ether, and ethyl acetate, which are similar in nature to the hydrates.
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