Molybdenum 3 cores

The preparation typically involves a condensation reaction of acidic molybdenum sources such as molybdenum trioxide, molybdic acid and ammonium molybdate with dialkylammonium dialkyldithiocarbamate salts formed in situ by reaction of carbon disulphide and dialkylamine [45]. The extent of sulphurisation of the molybdenum core can be increased by the introduction of sulphurising agents such as sodiumhydrosulphide [46]. Patent literature reports that the greatest antioxidant effect of molybdenum dialkyldithiocarbamates is seen when combined with aminic and phenolic antioxidants [47]. 

The yariation in catalytic function with increasing oxygen coyerage is in excellent agreement with surface characterization by molybdenum core leyel shifts and surface polarizability measurements. Clearly the physical measurements were performed on the actual catalytically actiye sites, and the nature of the actiye sites has been established. The catalytic results combined with the spectroscopic data also serve to calibrate the minimum molybdenum oxidation state required for acid catalyzed C-C bond breaking and formation of a secondary carbenium ion, namely. Mo(IV). 

Fig. 4. Representative structures for compounds of molybdenum(IV) (a) bis(diaIkyldithiocarbamato)oxomolybdenum(IV), MoO(S2CNR2)2, where R = alkyl (b) / Jtetracyanodioxomolybdenum(IV), Mo02(CN) (c) M03SJ3 (d) Mo3S4(SCH2CH2 )1 (e) Mo304(H20)g" (f) the Mo M S thiocubane core stmcture (g) bis(cyclopentadienyl)dichloromolybdenum(IV), CP2M0CI2, where Cp = cyclopentadienyl.

Fig. 5. Representative structures for compounds of molybdenum(III) (a) hexacholoromolybdenum(III) ion, MoClg (b) bexabis(dimethylamiHo)dimo1ybdeniim (TTT), Mo (N(CH ) ) (c) the Mo S thiocubane core stmcture (d) dichlorocyclopentadienyl triaIkylphosphinedichloromolybdenum(III), CpMo(PR2)Cl2, where Cp = cyclopentadienyl and R = alkyl.

The dichloride of molybdenum(II) [13478-17-6] M0CI2, contains Mo CF g core units (Fig. 6c) having chloride bridges in its soHd-state stmcture. Similar or identical hexanuclear units are known in soluble species such as Mo3Ch 24 other derivatives containing the Mo CF g core. These compounds have been under investigation because of their photochemical and photoluminescent activity (see Photochemical technology) (36,37). The hexanuclear... 

Zn, Ni, Cu, and W, yet is the seventh most abundant element overall because Cr is concentrated in the earth s core and mantle (1,2). It has atomic number 24 and belongs to Group 6 (VIB) of the Periodic Table and is positioned between vanadium and manganese. Other Group 6 members are molybdenum and tungsten. On a toimage basis, chromium ranks fourth among the metals and thirteenth of aU mineral commodities in commercial production. 

Using one of the core materials listed in Table D-1, the designer can feel reasonably confident that he or she has made the best choice for a ferrite. Mopermalloy is a ferrite alloy that has nonmagnetic molybdenum mixed with it. The molybdenum acts as a distributed air-gap within the material, which makes the material excellent for dc biased or unipolar applications. Unfortunately, it is only available in toroid core styles, and it typically used for output filter chokes. 

The set of Mo(V) EPR signals detected in D. gigas and D. desulfuricans AORs shows close homology with the molybdenum-containing hydroxylase group. Mossbauer and X/Q-band EPR spectroscopic studies 208, 216) complemented the UV/visible and CD studies and the assignment of the [2Fe-2S] arrangement of the iron-sulfur cores. 

Solid-state cluster chemistry is dominated by octahedral (M 5L8)L6 and (MsLi2)L units which are the focus of this paper. These two cluster types are different in the way the metal octahedral core is surrounded by the ligands. In (MsLg)L6-type clusters (Fig. 6.1a), typical for molybdenum and rhenium halides, chalcogenides, and chalcohalides, eight innei hgands (L ) cap the octahedron faces and six outer ligands (L ) are located in the apical positions [9]. For metals with a smaller number of valence electrons, the (M6L i2)L -type clusters... 

When applying these methods to the study of molybdenum complexes Voityuk and Rosch [25, 41] found that the use of the AMI core-repulsion function (Eq. 5-6) led to some systematic deviations for some Mo—X bond lengths. To address these problems, important changes to the core-repulsion function were made by the introduction of bond-specific parameters (omo-x and 8 io-x, Eq. 5-9) [22, 25], The idea of using bond-specific core repulsion parameters is not new, since the AMI parameterisation of boron used bond-specific Gaussian functions to improve the final results [42],... 

It must be taken into account that there are dendrimers in which the central core is constituted by metallic assemblies.38 1 This is the case for example of the multiferrocene assemblies illustrated in Figure 31, which bear a phthalocyaninato-zinc, a tetraplatinum, a hexatin, or a hexa-molybdenum central core, respectively.55-58... 

Compound 23 is the most active of the only two commercially available (Strem Chemicals, Inc.) ROMP catalysts (the other one being the corresponding nonfluorinated product). Its availability prompted the author to test it before similar catalysts that contain tungsten as a core metal and that have been shown to be more stable and more active than the molybdenum ones molybdenum catalysts seem, nevertheless, to tolerate more functionalities than the tungsten ones. 

In the earlier examples, the binuclear complexes with a M02S3 core clearly cannot be seen as modeling the metal sites in FeMo—co since it is known to contain a single molybdenum center [74]. However, what is suggested by these studies is that several steps (if not all) of the reduction of dinitrogen to ammonia by Mo-nitrogenase could take place at a... 

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