Clusters geometric structure

An alternative approach is to relate variations in reactivity with metal clusters structures. Unfortunately even less is known about their geometric arrangement than their electronic structure. Suggestions made in the literature will be summarized and simple ideas of the degree of coordi native unsaturation will be presented. 

Two representative clusters that are different in shape are exemplified. One is a compact cluster—that is, a geometrically packed structure—which is located... 

Fig. 1.18. Mass-selected negative ion photoelectron spectra for Au 02 clusters (n = 1,2,4). The line structures in the spectra correspond to the vibrational frequencies of the neutral state in the geometry of the anion. Indicated are also the geometric equilibrium structures of the cluster complexes obtained from DFT calculations [124,125]...

A. Clusters of noble gas atoms give geometrical shell structure... 

We described boratiranes and boriranes with one boron substituent at each ring carbon atom. The geometrical distortions found experimentally in the X-ray structures as well as by model computations can be understood in terms of variably strong hyperconjugation between a(C-B) bonds and the formally empty p-orbitals of more or less electron deficient boron atoms. Two electron reduction of an oxatriborabicyclohexane leads to ex-treme distortion of the bicyclic to a cluster structure by formation of a 3c,2e-BBB-bond. 

Becker J, Rademann K, Hensel F (1991) Ultraviolet photoelectron studies of the molecules Ses, See, Sev and Seg with relevance to their geometrical structure. Z Phys 019 229-231 TriboUet B, Benamar A, Rayane D, Broyer PM (1993) Experimental studies on selenium cluster structures. Z Phys 026 352-354... 

In cluster science, clusters are usually generated in gas phase and detected via time of flight mass spectroscope and other spectroscopic means, e.g., photoelectron spectrum, infrared spectrum, electron diffraction. However, direct determination of the cluster structure by experiment alone is still rather difficult so far. Alternatively, by combining theoretical simulations and experimental data, a complete description of the geometric structure and the corresponding physical properties of a cluster can be established. 

The geometric arrangement of atoms is of paramount interest in cluster science. Mass spectrometry has provided essential clues to cluster structure and morphology, even though the approach is indirect. In short, one attempts to relate anomalies in the size distribution of clusters to anomalies in their properties, such as stability, reactivity or ionization energy. 

Winter B J, Parks E K and Riley S J 1991 Copper clusters the interplay between electronic and geometrical structure J. Chem. Rhys. 94 8618... 

When building clusters by coating the fullerenes with metal, features similar to the electronic and geometric shells found in pure metal clusters[9] are observed in the mass spectra. In the case of fullerene molecules coated with alkaline earth metals (section 3), we find that a particularly stable structure is formed... 

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