Interstitial main group atoms

Hexacapped cubic species with an interstitial main group element instead of a transition metal are rather scarce. Hitherto, only one example, namely the 119-MVE compound Nig(//g-As)(/i4-As)6(PPh3)8 (6) has been prepared. The structural arrangement of this cluster reported by Fenske and coworkers is strongly related to that of the metal-centered Ni9(//4-As)6(P-Bu 3)g with comparable Nis Nis and Nij-As separations. 

The possibility of encapsulating main group atoms in the middle of the metallic Mg(/i4-E)6Lg cube was initially examined by Wheeler few years ago. Using EH 

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Few complexes are known containing interstitial main-group atoms that also fall within the scope of this review (see 79-81), but one example containing antimony has been reported by Vidal (143), in which this element resides in the center of an icosahedron of rhodium atoms, [SbRhI2(CO)27]3 (143) (Fig. 40). 

Anionic carbonyl clusters with interstitial main-group atoms... 

Table 2. Closo, nido and arachno transition metal clusters (based on deltahedra with more than 6 skeletal atoms) possessing interstitial main group atoms...

One general synthetic route to transition metal carbonyl clusters incorporating interstitial main-group atoms involves cluster build-up by the simple thermolysis of... 

Interest in the synthesis of transition metal carbonyl clusters incorporating interstitial main-group atoms is because they provide a conceptual bridge between or-ganometallic chemistry and the areas of inorganic solid-state and surface chemistry. In addition to serving as useful models for either solid-state binary alloys or for the chemisorption of heteroatoms on the step-site of a metal surface, these discrete molecular clusters are often markedly more stable, especially toward the temperatures and pressures required for catalytic reactions. 

This result emphasizes the role of interstitial atoms in determining the electronic structure and the properties of these materials. The NigCe core of the cluster can be regarded as a microscopic fragment of a nickel carbide. The interstitial main group atoms form strong bonds with the surroundings these bonds may be viewed as initial step in the formation of a different phase (carbides, nitrides, etc.) within the cluster complex. 

Halet J-F (1992) Theoretical aspects of the bonding in transition metal carbonyl clusters with interstitial main group atoms. In Gielen M (ed) Topics in physical organometallic chemistry, vol 4. Freund Publishing House, London, pp 221-288... 

The spread of the NMR chemical shifts over a more or less wide range is a common feature for all the interstitial main group atoms. A comparison of the... 

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