Molybdenum atoms, reactions

Fe—Fe bond can be assigned structures 201 or 202 based on spectral data. The other product of this reaction is 193 (R = r-Bu), however, it is produced in minor amounts. Complexes 199 (R = R = r-Bu, R = Ph, R = r-Bu) were obtained. Reaction of 146 (M = Mo, R = Ph, R = R = Ft, R = r" = Me) with (benzyli-deneacetone)iron carbonyl gives rise to the bimetallic complex 200 (M = Mo), which reacts further with the free phosphole to form the bimetallic heteronuclear sandwich 203. The preferable coordination of the molybdenum atom to the dienic system of the second phosphole nucleus is rather unusual. The molybdenum atom is believed to have a greater tendency to coordinate via the trivalent phosphorus atom than via the dienic system. 

Understanding the mechanism of reactions on the catalyst surface requires an adequate description of the surface it must modelled either by infinite slab or by clusters having similar properties. The interesting feature of the M0O3 surface is the existence of three structurally different oxygen atoms, a terminal one O] coordinated to one molybdenum atom, and two bridge-like oxygen atoms On and Om, coordinated to two and three Mo atoms, respectively. 

Central to catalysis is the notion of the catalytic site. It is defined as the catalytic center involved in the reaction steps, and, in Figure 8.1, is the molybdenum atom where the reactions take place. Since all catalytic centers are the same for molecular catalysts, the elementary steps are bimolecular or unimolecular steps with the same rate laws which characterize the homogeneous reactions in Chapter 7. However, if the reaction takes place in solution, the individual rate constants may depend on the nonreactive ligands and the solution composition in addition to temperature. 

Compound 12 displays an altogether different reactivity pattern upon treatment with iodine in the presence of an ether or a thioether. Thus, the sole product of the reaction of 12 in THF with iodine was the anionic Mo complex [N(PPh3)2][2,2,2-(CO)3-2-I-7-0(CH2)4-c/oxo-2,1-MoCBioHio] (67), with the carborane cage having undergone a substitution at a boron vertex. The substitution occurs at a p boron atom in the CBBBB face that ligates the molybdenum atom. When 67 is treated with further iodine in THF no reaction occurs. However, treatment with iodine using... 

Phosphides. The crystal structure of MogPj has been shown to involve trigonal prisms of molybdenum atoms each enclosing a central phosphorus atom. M0P4 has been prepared by reaction of the elements at 15—65 kbar and shown to be isostructural with CrP, and therefore to involve the metal atom surrounded by six phosphorus atoms in a distorted octahedral manner. ... 

The prosthetic group associated with the molybdenum atom of the molybdenum cofactor found in most molybdenum-containing enzymes except nitrogenase (See Molybdenum Cofactor). Many of these enzymes catalyze two-electron redox reactions involving the net exchange of an oxygen atom between the substrate and water. In bacterial enzymes a nucleotide is linked to the phosphoryl group. 

The maximum pressure that should be tolerated in a metal atom reactor is a point of controversy among various workers in this field. High pressures favor reaction in the gas phase with respect to those in the matrix. Where different products are obtained from the gas and condensed phases, the former products begin to appear at pressures of 10 4 torr. The molybdenum atom syntheses described in this volume are best carried out under 10 4 torr and with apparatus described in synthesis number 16. Skell and co-workers consider this apparatus necessary and appropriate for all work. 

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