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760 Coordination Compounds

TABLE XII Some “Specific” Complexing Agents for ous solutions are Na 3 [Au(S 2 O 3 ) 2 ] (sanochrysine), sodium
Aqueous Iron and Natural Analogs gold thiomalate (myocrisin), and a phosphine complex
Compound (Solganol). These may have grave side effects but are com-
(oxidation state) Ligand Natural example monly effective in restoring expression to locked joints.
The detailed mechanism of action is unknown, but an in-
Fe(OH 2 ) 3+ Salicylate —
6 triguing fact is that when two enantiomeric joints are ex-
(III) (2-hydroxybenzoate) —
amined, one affected, the other not (such as two elbows),
Hydroxamic acids Ferrioxamine
Fe(OH 2 ) 2+ 2,2 -Bipyridyl gold is found only in the rheumatic or arthritic joint.

6
(II) Platinum therapy, discovered by Rosenberg, used cis-
dichlorodiammineplatinum(II) (see Table IX). This is sold
under the names Platinol, cis-platin, or Neo-platin. It is
thought to act by interfering with nucleic acid replication.
Platinosis (a sensitivity, revealed as an allergy, to certain
complex compounds of platinum) has become a notifiable
industrial disease in France. It has been known since the
early years of this century among workers in factories
producing platinum chemicals. The novel utility of this
a Structure 52 and derivatives known as caerulomycins B, C, and

D (all based on the 2,2 -bipyridyl-6-aldoxime moiety) are isolated simplest of coordination compounds, cis-[Pt(NH 3 ) 2 Cl 2 ],
from Streptomyces caeruleus. is certainly a major breakthrough in cancer chemotherapy.
b Ferropyrimine (53) is isolated from the organism Erwinia Ligands by themselves are often effective drugs or
rhapontici, the cause of crown rot in rhubarb, which is also a rich detoxificants. For example, D-penicil-lamine (3, a substi-
source of the chelating agent (C 2 O 4 ) 2− , oxalate, or ethane 1,2-dioate.
tuted cysteine) is used to mobilize copper deposited in
reducing tissues in patients with Wilson’s disease (hep-
atolenticular degeneration), a hereditary defect in cop-
on concentration, temperature, ionic strength, pH, and so
per metabolism. The copper transport protein (cerulo-
forth, will come to equilibrium with the environment.
plasmin) of blood plasma is faulty and bonds copper
Establishing the actual nature (speciation) of the metal-
ions less effectively than it should. The enantiomeric
containing ions and molecules (species) that are present
L-penicillamine is ineffective as a treatment. If (as may
in such a given environment is obviously important. It
happen) D-penicillamine is either inactive or gives rise
is best done, at present, by a combination of potentiom-
to intense nausea, triethylenetetraamine (trien; 4) is often
etry [described in Section II.G, Eqs. (41) and (42)] and
used.
spectroscopic analysis. The potentiometry defines ranges
of possible speciation, and spectroscopy decides among
them. Characteristic therapeutic effects [other than those SEE ALSO THE FOLLOWING ARTICLES
of the separated constituent parts, metal ion and ligand(s)
added separately] are therefore to be expected for kinet- CATALYSIS,HOMOGENEOUS • CATALYSIS,INDUSTRIAL
ically inert compounds. Synergic effects are, of course, • ELECTRON TRANSFER REACTIONS • KINETICS (CHEM-
conceivable for kinetically labile metal ions with particu- ISTRY) • LIGAND FIELD CONCEPT • NOBLE METALS •
lar ligands. RARE EARTH ELEMENTS AND MATERIALS
The two best-known therapies involving kinetically in-
ert coordination compounds are chrysotherapy (treatment
of rheumatoid arthritis with gold compounds) and the rel- BIBLIOGRAPHY
atively new treatment of certain cancers with platinum
compounds. Kauffman, G. B. (ed.) (1994). “Coordination Chemistry, A Century of
Progress,” ACS Symposium Series 565; American Chemical Society,
In chrysotherapy, following earlier uses of “potable
Washington, D.C.
gold” and of “colloidal gold,” the intact complex com- Wilkinson, G., Gillard, R. D., and McCleverty, J. A. (1987). “Compre-
pounds (with trade names) used in the form of aque- hensive Coordination Chemistry,” Vols. 1–7, Pergamon Press, Oxford.