Cluster compounds molybdenum-sulfur

Table 3.4 lists values for A Eq and for some important oxidation and spin states found in bioinorganic molecules. Data are taken from reference 24 and from Table 1 of reference 25 for hemoglobin, myoglobin, and the picket-fence porphyrin model compound, FeTpivPP(l-Melm).25 The myoglobin and hemoglobin model compounds are discussed in Section 4.8.2. Reference 26 provides the Table 3.4 data on iron sulfur clusters found in many bioinorganic species.26 The unusual iron-sulfur and iron-molybdenum-sulfur clusters found in the enzyme nitrogenase are discussed more fully below and in Chapter 6. 

Cluster compounds, chiral, 27 191 molybdenum-sulfur, 27 47 transition metal, 27 182... 

Methods of preparing molybdenum(V) complexes with M02O4 cores have been published. However, those of sulfur-bridged molybdenum(V) complexes with M02O3S and M02O2S2 cores remain difficult. Molybdenum-sulfur cluster compounds attract much attention since almost all molybdenum enzymes contain both molybdenum and sulfur, being always accompanied by iron. 

Cyclopentadienyl molybdenum-sulfur compounds are useful synthons for the preparation of Mo—M—S (e.g. M = Fe (see Section 36.6.2), Co, Ni) clusters " in reactions with metal carbonyls. However, the principal interest in molecules of this class has arisen because of the reactivity of the Mo—S system, primarily in respect of the making and breaking of S—H... 

The situation is very similar in the Chevrel phases. These are ternary molybdenum chalcogenides A,.[Mo6Xg] (A = metal, X = S, Se) that have attracted much attention because of their physical properties, especially as superconductors. The parent compound is PbMo6Sg it contains Mo6Sg clusters that are linked with each other in such a way that the free coordination sites of one cluster are occupied by sulfur atoms of adjacent clusters (Fig. 13.9). The electric properties of Chevrel phases depend on the number of valence electrons. With 24 electrons per cluster (one electron pair for each edge of the... 

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