Chemistry Reference
In-Depth Information
Table 7.1
Key physical methods available for separation and isolation of complexes and for
determining basic information about the isolated compound.
Method
Sample and
device
requirements
Outcome expected
Separation Techniques
Crystallization
A solution of either the pure
complex or a mixture of
complex species.
Selective crystallization of a pure
complex; this may, but need
not, follow chromatographic
separation of solution species.
Ion chromatography
Solutions of soluble ionic
complexes.
Ion chromatography columns
packed with appropriate
cationic or anionic polymer
resin.
Separation of ions mainly
according to charge, and
possibly assignment of charge.
(Examination of separated bands
of compounds directly as they
exit the column by tandem
instrumental methods is also
possible.)
High pressure liquid
chromatography
(HPLC)
Liquids or solutions.
Commercial HPLC instrument
with appropriate packed
columns.
Separation of neutral and/or
ionic species.
Gas chromatography
Gaseous or volatile liquid
samples.
Gas chromatograph instrument
with capillary or packed
columns.
Separation of volatile samples,
usually applicable only to
some neutral low molecular
weight complexes.
Identification by comparison with
known standards is possible.
Basic Analytical Procedures
Elemental analysis
Pure compound, as liquid, solid
or solution of known
concentration.
Elemental autoanalyser
(for C,
H, N, S, O only usually) or
else
atomic absorption (AAS)
or
atomic emission (ICP-AES)
spectrometers
(for other
elements).
Percentage composition of
elements determined, allowing
component elements and the
empirical formula to be
defined.
Thermal analysis
techniques
[Thermogravimetric
analysis, differential
thermal analysis]
Solid or liquid sample.
Thermogravimetric analyser.
Mass change with temperature;
information on number of
waters of crystallization,
ligand loss and complex
transformation with increasing
temperature obtained.
Conductivity
A solution of a pure compound
of known concentration.
Conductivity meter and probe.
Ionic or neutral character of
complex, and possibly the
overall charge of the complex
ion.
Magnetic
measurements
Solid or concentrated solution.
Magnetobalance or
magnetometer.
(A limited
NMR-based method
is
also available.)
Defines dia- or para-magnetism;
number of unpaired electrons,
and some inferences about
gross symmetry possible.
Variable-temperature
behaviour provides
information on metal-metal
interactions in polymetallic
species.
