Molybdenum Mo i

What do the ions of the following elements have in common calcium, Ca chlorine. Cl chromium, Cr cobalt, Co copper, Cu fluorine, F iodine, I iron, Fe magnesium. Mg manganese, Mn molybdenum, Mo nickel, Ni phosphorus, P potassium. K selenium, Se sodium, Na sulfur, S zinc, Zn They are all dietary minerals essential for good health, but can be harmful, even lethal, when consumed in excessive amounts. 

Some elements are essential to the composition or function of the body. Since the body is mostly water, hydrogen and oxygen are obviously essential elements. Carbon (C) is a component of all life molecules, including proteins, lipids, and carbohydrates. Nitrogen (N) is in all proteins. The other essential nonmetals are phosphorus (P), sulfur (S), chlorine (Cl), selenium (Se), fluorine (F), and iodine (I). The latter two are among the essential trace elements that are required in only small quantities, particularly as constituents of enzymes or as cofactors (nonprotein species essential for enzyme function). The metals present in macro amounts in the body are sodium (Na), potassium (K), and calcium (Ca). Essential trace elements are chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), magnesium (Mg), molybdenum (Mo), nickel (Ni), and perhaps more elements that have not yet been established as essential. 

Early attempts to prepare carbonyl halides of molybdenum failed, " until pioneering work by Colton and Tomkins in 1966 described the reaction of [Mo(CO)e] with liquid chlorine at -78°C to yield the tetracar-bonyl dimer, [ Mo(/i-Cl)Cl(CO)4 2] [Eq. (1)]. In the same year the bromo-bridged dimer, [ Mo()u-Br)Br(CO)4 2], was prepared in an analogous manner. 

Bimetallic molybdenum nitrosyl complexes, (containing Mo(I), i.e. a 17e species) with conjugated bridging ligands of the bispyridine family, or the bisphenolate family, present widely separated reduction waves, as shown by McCleverty, Ward, and others [86], The separation can be observed with spacers containing up to four double bonds, or four phenylene units. 

The central metal atom is thought to be M(II), while the outer molybdenum atoms are classified as Mo(0). Chemical oxidation by iodine affords a neutral molecule formulated as depicted in Scheme 4. The change in oxidation state involves the oxidation of both the outer molybdenum atoms to Mo(I). 

In acetonitrile solution, it undergoes a quasireversible one-electron reduction (E° = — 1.99 V, at — 40 °C) as well as an irreversible one-electron oxidation (Ep= + 0.18 V, at — 40 °C). Such redox changes are attributed to the reduction of the central tungsten atom and to the oxidation of one outer molybdenum atom, respectively. At variance with the previously discussed thiolate bridged trimetal clusters (which undergo a chemically reversible two-electron oxidation), the occurrence of an irreversible one-electron oxidation is attributed to the inability of the central W(VI) to form metal-metal bonds with the outer Mo(I) moieties [74]. 

The chief purpose of preparing this book was to condense all the information available on the subject of molybdenum (Mo) as it relates to soils, crops, and livestock. Because the problems related to the requirements for Mo in soil and in crop production differ considerably from one part of the world to another, I attempted to solicit the assistance of experts from the different regions of the world who were best suited to write about the topics of the various chapters. These contributions by authors from different geographical areas have helped to provide a broader viewpoint of the subject matter than would have been the case if only a single author had prepared the book in its entirety. 

The [M04I7] unit can also be related to the cube arrangement, with two adjacent molybdenum atoms removed, and the two related chlorine atoms at comers of the cube replaced by one at the centre of the edge linking these corners as shown in Figure 3. In this unit the two three-coordinate iodine atoms have much smaller Mo—I—Mo angles, presumably due to the larger size of the iodine atom. 

A molybdenum[Pg.114]

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