Hexagon prism cluster

The dilithium triimidochalcogenites [Ei2 E(N Bu)3 ]2 form dimeric structures in which two pyramidal [E(N Bu)3] dianions are bridged by four lithium cations to form distorted, hexagonal prisms of the type 10.13. A fascinating feature of these cluster systems is the formation of intensely coloured [deep blue (E = S) or green (E = Se)] solutions upon contact with air. The EPR spectra of these solutions (Section 3.4), indicate that one-electron oxidation of 10.13a or 10.13b is accompanied by removal of one Ei" ion from the cluster to give neutral radicals in which the dianion [E(N Bu)3] and the radical monoanion [E(N Bu)3] are bridged by three ions. ... 

Fig. 8. Sodalite and hexagonal prism site I and II cation locations in Ag/faujasites. Configuration (a) shows the normal cation locations with occupied sites at SI, SI and SII. Configuration (b) shows cation sites that have resulted from cation and/or cluster migration upon vacuum thermal treatment. This configuration shows occupied sites at SI, SII, and SII (Hutson and Yang, 2000).

The hydroxyl groups of the first kind are already absent in faujasites, quite in accordance with the cluster model predictions. Instead, two other bands with fundamental stretching vibration frequencies of 3640 and 3650 cm-1 were observed in Y zeolites. They were assigned to OH-II groups located within the large cavities (3650 cm 1) and to OH-II groups positioned inside the hexagonal prisms (3555 cm 1) (82). 

DRS has also been successfully applied to follow the kinetics of silver-cluster formation in AgX monitoring the intensity changes of the 410 nm band which is assumed to originate from Agj + clusters in the SI -SI-ST position of the hexagonal prisms [144] The rate-determining step has been rationalized by a model of diffusion into a sphere. 

Abstract The concept of stable superatoms, molecular species which mimic the shell closures emphasised by Lewis and Kossel, has become an important paradigm of stability in cluster chemistry. In this review we discuss recent work, both experimental and theoretical, on the family of endohedral clusters M Ex, where M is a transition metal ion and E is a member of group 14 (Si, Ge, Sn, Pb). The structural chemistry within this family is very varied, ranging from deltahedral motifs for the heavier tetrels to open 3-connected stmctures such as the hexagonal prism in Cr Sii2- We explore the arguments that have been presented to rationalise these structural trends and their implications for chemical bmiding. 

The solvent-free cluster 17 crystallizes in the monoclinic space group P21/c and comprises a hexagonal Mg6P6 prism with disordering... 

The Sn6P6 cluster 19c crystallizes in the triclinic space group PI. It forms a distorted hexagonal Sn6P6 prism with three-coordinated Sn and four-coordinated P atoms (Fig. 20) (39), that is, the structure is topologically identical with that of solvent-free 17 (see Fig. 18). 

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