Comments and Conclusion

In this article we have shown that the electronic structures of transition metal compounds based on a cubic architecture can be rationalized, by use of results obtained from molecular orbital calculations, leading to some interesting extensions of the electron-counting PSEP rules. Indeed, the cluster topology of the different cubic cluster categories is highly dependent on several parameters which can be calibrated. 

The empty hexacapped Mg(/i4-E)6Lv architecture is permitted for a broad range of electron counts. The upper limit (120 MVEs) corresponds to a closed-shell elec- 

New eonducting and/or magnetic extended structures resulting from the assem- 

Cubic clusters are characterized by an electronic structure which is either molecular or metallic in nature. Accurate measurements of their physical properties may provide some indication of the particle size at which the typical properties of a bulk metal begin to appear.  

Professor D. Fenske, Dr. E. Furet, Dr. A. Le Beuze, Professor K. H. Whitmire, and B. Zouchoune are gratefully acknowledged for their participation in some of the work discussed in this article. Molecular diagrams were based on X-ray crystallographic data were prepared with the Ca.R.Ine Cristallographie 3.0.1 program (C. Boudias and D. Monceau, 1989-1994). 

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Final conclusions and comments will be drawn in Section VII. 

C. Auerbach, Unpublished data. Conclusions and comments of a workshop held in U.S.A. (1971). 

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