Aluminum cluster

Gantefor G, Meiwes-Broer K H and Lutz H O 1988 Photodetachment spectroscopy of cold aluminum cluster anions Phys. Rev. A 37 2716... 

The acute-angle coordinations were similarly predicted for tricoordinated metal complexes [66]. The acute O-Al-O angles of trihydrated aluminum clusters were reported [67]. 

The isolation methods and the structures of the metalloid aluminum clusters discussed here have shown the particular suitability of the ligand N(SiMe3)2 for... 

The disappearance of the aluminum clusters is evidently by etching reactions ... 

Giant Aluminum Clusters with Shell Structures Consisting of Nested Polyhedra Pieces of Icosahedral Quasicrystals... 

The lack of a single ordering principle is a shortcoming particularly for the gallium clusters, since there are a larger number of them compared with the corresponding aluminum clusters as a result of their improved synthesis procedures (cf. Section 2.3.3). A purely formal means of classification for the gallium clusters... 

The isolated doped aluminum clusters L Ali2 with various dopants L have been systematically calculated earlier [62]. In [35] it was predicted that the dodecahedral isomer AUoCbo (4) is a high-lying intermediate which is, by 1 30-150 kcal/mol, less favorable as compared with the more compact... 

Rexer EF, Jellinek J, Krissinel EB, Parks EK, Riley SJ (2002) Theoretical and experimental studies of the structures of 12-, 13-, and 14-atom bimetallic nickel/aluminum clusters. J Chem Phys 117 82... 

The most size-specific reaction is that of aluminum clusters with D2, as shown in Fig. 2. The 6-atom cluster of aluminum is the most reactive, and no reaction is observed for clusters containing fewer atoms. Reactivity rapidly falls off for AI7 and Alg. Under the highest Dj pressures employed reaction can be observed up to about Al j. Similar results are obtained for H2, but with relative rate constants about 1.7 0.4 higher than for D2. The primary products of the reaction are A1 D2, and unlike most other systems discussed below, once one molecule has been added, the cluster adduct does not appear to react further. Saturation coverage appears to be one molecule of hydrogen. 

Figure 2. Reactivity of aluminum clusters toward D2. (a) Time-of-flight mass spectrum of bare Al and their deuterium addition products. Dashed trace—reference spectrum in which He only is pulsed into reactor, solid trace—Dj/He mixture is used, (b) Relative rate constants of Al (n = 2-14) toward chemisorption of Dj obtained from data such as that presented in (a). (From Cox et al. )...

All aluminum clusters react with CO, but Alg reacts about twice as fast as any other cluster. The Alg cluster is nearly a hundred times more reactive toward CO than Hj. In addition no Al —CO adducts are detected. Studies of CO chemisorption on aluminum surfaces ° indicate that the bond strength is only about 8 kcal/mol, consistent with theoretical calculations.The fact that Al —CO and Cu —CO are not observed as products may be due to unimolecular decomposition in the beam, or dissociation during the photo-ionization/detection process. The answer must await further experiments. 

Surprisingly, aluminum cluster reactivity with O2 depends sensitively on the cluster size. The atom and dimer are very reactive, but a sharp decrease in reactivity is observed for the trimer. Above the trimer a nearly montonic increase in reactivity occurs as the number of aluminum atoms increases. By n = 25-30 the clusters are once again nearly as reactive as the dimer. The dominant product peak is AI3O2, but it is not produced directly through chemisorption of O2 onto an AI3 cluster. The species appears to be the product... 

Aluminum clusters react more rapidly with methanoP " than either Dj or DjO. Alj, A1 4, and AI22 are the least reactive clusters. As a result of sequential addition reactions the observed product peaks are A1 (CH30H) with m = 1, 2, and 3. At low extent of reaction, products with m = 1 are obtained in the highest yield. The peak reactivity, occuring at Ali -i, is about 500 times greater than that of the most reactive cluster (Al ) toward D2 - As the methanol partial pressure is increased, the mass spectra become very complicated. 

Aluminum clusters selectively chemisorb D2O, with peak reactivity occurring at AI q. The rate constants for AI q is 50 times greater than that of the most reactive cluster (AI5) with The reaction is facile, not only for the... 

Aluminum clusters also dehydrogenate H2S. A proposed reaction sequence is as follows ... 

Pesiherbe G H and Hase W L 1996 Statistical anharmonic unimolecular rate constants for the dissociation of fluxional molecules. Application to aluminum clusters J, Chem. Rhys. 105 7432-47... 

Ray, U., Jarrold, M.F., Bower, J.E., Kraus, J.S., Photodissociation kinetics of aluminum cluster ions determination of cluster dissociation energies. J. Chem. Phys. 1989, 91, 2912. 

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