Beyond Deltahedral Clusters

The bottom-up synthesis of well-defined (semi)metal and intermetalloid clusters that can reach the nanometer scale represents a major challenge. Deltahedral structures reach a limit in size unless more capable templates are found. However, Zintl ions themselves can serve as building units for the formation of larger structures, including classical and nonclassical tetrel-tetrel bonds. Two further examples justify the plan to use such tetrel dusters as precursors for nanoscale dusters  

The authors like to thank the Deutsche Forschungsgemeinschaft (FA 198/6-1) for financial support, and Dr A. Schier for revising the manuscript. 

Acta Crystallogr., 6, 197 Hoch, C. and Rohr, C. (2002) Z. Anorg. Allg. Chem., 628, 1541. 

90 Schmidbaur, H. (ed.) (1999) Gold - Progress in Chemistry, Biochemistry and Technology, John Wiley Sons, Chichester. 

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More advanced mathematical aspects of aromaticity are given in other references [33, 34]. Some alternative methods beyond the scope of this chapter for the study of aromaticity in deltahedral molecules include tensor surface harmonic theory [35-38] and the related Hirsch 2 N -b 1) electron-counting rule for spherical aromaticity [39]. The topological solitons of nonlinear field theory related to the Skyrmions of nuclear physics have also been used to describe aromatic cluster molecules [40]. 

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