Metalloid/metal displacement

The relationship of the wheel-rim-type structure of 62 to the metal can be demonstrated by a 30° rotation of the two centered Alg rings followed by a shift of the six rings towards each other (cf. Figure 2.3-13) [92], The other possibility of the formation of an Al14 polyhedron with point symmetry by displacement of the two naked central atoms in the direction of a polyhedral entity has been shown to be energetically unfavorable by quantum chemical calculations i.e., the observed metalloid structure (Figure 2.3-13) is favored over the anticipated polyhedral structure as described by Wade-Mingos [5, 96] (see Chapter 1.1.2). 

While little has been written by the Russian group regarding the mechanisms of the reactions, most of the data are readily accommodated by processes involving six-membered transition states. Thus nucleophilic attack on the metal or metalloid atom N by the carbonyl oxygen with displacement of halide from one metalloid to the other would account for the formation of the oxyalkene isolated. 

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