Chemistry Reference
In-Depth Information
HIGH-VALENT Cr, Mn, AND
Fe SPECIES
High-valent metal-oxo species are involved in chemical, industrial, biological,
and environmental oxidations [1-5]. Compounds of Cr in the pentavalent
oxidation state with the formula M
3
CrO
8
(M = Na
+
, K
+
, Cs
+
, Rb
+
, and
NH
+
)
have shown magnetic and ferroelectric properties for their possible applica-
tions in data storage and manipulations [6]. Compounds of Cr(VI) have useful
properties, which include tensile strength and malleability and, hence, are used
in various industries such as stainless steel welding, chrome plating, and
production of dyes. The oxidative degradation of organic pollutants using
chromate-induced activation of hydrogen peroxide has also been proposed as
a potential advanced oxidation process [7]. Applications of Cr compounds may
lead to environmental hazards due to their carcinogenicity and mammalian
toxicity [8, 9]. High-valent complexes of Mn play a role in synthetic chemistry
and in biometric oxidation reactions. For example, high-valent manganese-oxo
species have been proposed in the oxygen evolving complex (OEC) of pho-
tosystem II (PSII) [5, 10, 11]. High-valent-iron-oxo species have been invoked
in oxidation reactions of heme and nonheme iron enzymes [12-16]. Ferrates
(
Fe O
2−
) have shown properties of disinfection and oxidation to
purify water [17-22].
In this chapter, the basic chemistry of high-valent compounds of Cr, Mn,
and Fe is presented, followed by a discussion on their reactivity with biological
compounds including amino acids, peptides, and proteins.
VI
V
3−
and
Fe O
4
4
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