Clusters oxide/hydroxides

In very acidic solutions, bismuth(III) exists in the form of the nonaaquo ion [Bi(H20)9] +, which is similar to the aquo complexes of the lanthanide ions, but partial hydrolysis of bismuth(III) salts leads to the formation of bismuth oxo clusters. The core structure of these complexes is often based upon a Bie octahedral core with oxide, hydroxide, or alkoxide functions bridging the edges and/or faces of the octahedron. The [Bi6(OH)i2] + ion (11) has been studied spectroscopically. In oxo clusters, the octahedron is face-bridged by eight oxo or alkoxide functions (12). Such core structures have been found in the hydrolysis of bismuth nitrate or perchlorate. ... 

Experiments were also conducted to see whether that the alkynyl groups are perfect substitutes for alkoxyl groups towards hydrolysis. Indeed, when 4 is hydrolyzed, it leads to the same butyltin oxide-hydroxide cluster with 12 tin atoms as when butyltin triisopropoxide is used. Moreover, with the more bulky triisopropylphenyl group linked to the tin, two unusual oxide-hydroxide clusters, one with 10 tin atoms and the other with six, are produced, depending on the experimental conditions. ... 

The formation of oxide-hydroxide metal clusters is considered in Sect. 20.4. Various places of their localization are discussed. One of them is associated with accommodation of metal oxide species in the cationic position of zeolites. The (Zn302) cluster formation was smdied and its activity in the dehydrogenation of ethane was calculated. Besides the condensation of polynuclear oxide species in ion-exchange positions a possibility of the grafting of small metal oxide clusters to zeolite or to pure silica lattice was considered on the example of immobilization of ZnO, (ZnO)2 and (ZnO)3 species. 

There are other ways of defining the partition coefficient, e.g., not as amount in solution divided by total amount in suspension, but as concentration in water relative to concentration on suspended matter. Here, Kd is set to 0.1 as a default value, which means that 10% of X is in solution and 90% is particulate. In practice, it is evident that the Kd-value is not a constant, but a variable, which depends on, e.g., (1) the given substance X, (2) lake water pH (and all cluster parameters linked to pH, such as hardness, conductivity, alkalinity, etc.), which influences the equilibrium between X and the particulate phase and the aggregation processes of the carrier particles, (3) the presence of colored substances (humus), which often have a strong affinity to many types of suspended substances (like metals, organic toxins, radioisotopes, etc.), and (4) the character of the particulate phase (if this is clays, humic matter, Fe-oxides/hydroxides, etc.). So, in more extensive ecosystem models, one would need comprehensive submodels to predict the partition coefficient. 

Figure 4.26. N2O decomposition catalyzed by Fe/ZSM-5. Cluster model of the binuclear iron oxide-hydroxide site ].

Trivalent Chemistry Cyclopentadienyl Rare Earth Metal Cluster Complexes Lanthanide Oxide/Hydroxide Complexes Oxide and Sulfide Nanomaterials Near-Infrared Materials. 

Lanthanides in Living Systems Lanthanides Coordination Chemistry Lanthanides Luminescence Applications Lmninescence Lanthanides Magnetic Resonance Imaging Lanthanide Oxide/Hydroxide Complexes Carboxylate Lanthanide Complexes with Multidentate Ligands Rare Earth Metal Cluster Complexes Supramolecular Chemistry from Sensors and Imaging Agents to Functional Mononuclear and Polynuclear Self-Assembly Lanthanide Complexes. 

Fig. S. Proposed cluster structure of the PbaOg units in lead oxide-hydroxide. =Pb =0.

Next, (1) CO binds to Cluster C to yield a Credi-CO complex (2) CO undergoes attack by the metal-bound hydroxide and is oxidized to CO2 as Cluster C is reduced by two electrons to the Cred2 state (3) CO2 is released and a second CO molecule binds to Cluster C to form a Cred2-CO complex (4) electrons are transferred from Cred2-CO to reduce Cluster B as the second molecule of CO2 is released. This mecha-... 

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