Thermal Reactions of Systems in Solution 1947-67
Inorganic chemical reactions
The Department has done pioneering work on the mechanisms of electron
transfer and of substitution reactions of inorganic compounds in solution.
Rates of various one-electron exchange reactions between metal ions have
been successfully measured, and the long-standing problem of the
ferrous-ferric exchange was solved. This has stimulated many investigations
in this field of chemical kinetics. It has been found that electron transfer
from iron(II) and vanadium(II) proceeds via binuclear complexes in which the
donor and acceptor metal ions are connected via a bridging group. Bridging
groups vary enormously in their ability to promote electron transfer.
Certain unsymmetrical groups possess two different sites for binding to a
metal center. Two complexes containing chromium(III) and thiocyanate have
been prepared. In one complex the thiocyanate is attached to the chromium
through the nitrogen atom and in the other through the sulfur atom. These
two complexes differ considerably in their properties, and they afford one
of the very few examples of linkage isomerism. A novel type of
intramolecular reorganization reaction, the mercury(II) catalyzed
reorganization of a thiocyanate complex, was discovered. In this reaction
the metal atom moves from one end of the thiocyanate group to the other.
This process may have important implications for mechanisms of more complex
reactions.
J. Silverman and R. W. Dodson, "The Exchange Reaction Between the Two
Oxidation States of Iron in Acid Solution," J. Phys. Chem. 56,
846 (1952).
N. Sutin, J. K. Rowley, and R. W. Dodson, "Chloride Complexes of Iron(III)
Ions and the Kinetics of the Chloride-Catalyzed Exchange Reaction Between
Iron(II) and Iron(III) Ions in Light and Heavy Water," J. Phys. Chem.
65, 1248 (1961).
A. Haim and N. Sutin, "The Reactions of Isothiocyanatobis(ethylene-
diamine)cobalt(III) Complexes with Chromium(II) and the Linkage
Isomerization of the Monothiocyanate Complex of Chromium(III)," J. Am.
Chem. Soc. 88, 434 (1966).
M. Orhanovic and N. Sutin, "The Mercury(II)-Catalyzed Isomerization of the
Sulfur-Bonded Monothiocyanate Complex of Chromium(III)," J. Am. Chem.
Soc. 90, 538 (1968).
Complex organic reactions at low
temperatures
At very low temperatures the chemical behavior of systems is often
simplified because reaction velocities are greatly decreased and because
many perturbations are diminished or eliminated. It thus becomes possible to
study with relative ease species which at ordinary temperatures have only
transitory existence. The study of chemical reactions in solutions at very
low temperatures has had much development at BNL. One of the substances
studied is chlorophyll b, which, in alkaline media at ordinary temperature,
reacts to produce a short-lived, irreversibly disappearing, red
intermediate. At l50° K measurements were made of this substance undergoing
slow, reversible reactions. Similarly, phosphorescences were observed which
would have been quenched at higher temperatures and which have proved to be
useful in the analysis of substances of biochemical interest.
S. Freed and K. M. Sancier, "Reversible Reaction of Chlorophyll Giving
the Red-Brown Intermediate of the Molisch Phase Test," Science 11,
655 (1953).
S. Freed and M. H. Vise, "On Phosphorimetry as Quantitative Microanalysis
with Application to Some Substances of Biochemical Interest," Anal.
Biochem. 5, 338 (1963).
Last Modified: June 28, 2012
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