Polyhedral rearrangements

Metallocarboranes and metalloboranes, discussed in 6.5.4, may be prepared from metal halides and carborane anions. Selected examples of complexes formed by thermal—or otherwise—induced polyhedral rearrangements of existing metallocarboranes are given in a few equations, and some other individual compounds are listed in tables. 

These ten-vertex monometallic complexes exhibit thermal polyhedral rearrangements similar to those mentioned previously. In fact, they were... 

B. F. G. Johnson, and A. Rodgers, Polyhedral Rearrangements and Fragmentation Reactions in Cluster Complexes, in The Chemistry of Metal Cluster Complexes (Eds. D.F. Shriver, H. D. Kaesz, and R. D. Adams, VCH Publishers, New York, 1990, Chap. 6). 

Figure 3-51. Lipscomb model of the rearrangement in polyhedral boranes top) with the polyhedral rearrangement of icosahedron/cuboctahedron/icosahedron [122],...

Table 1 Differences in repulsion energy coefficients, 10 AX, corresponding to polyhedral rearrangements of [M(ligand) ]...

Johnson BPG, Rodgers A, Polyhedral rearrangements and fragmentation reactions in cluster complexes. In Shriver DF et al. Eds., The Chemistry of Metal Cluster Complexes. VCH Publ., Weinheim, 1990 303. 

A number of thermal polyhedral rearrangements of 10-, 11-, and 12-vertex bimetallic cobaltocarbaboranes, Cp2Co2C2B H +2, have been studied. The rearrangements involved migration of Co, C, and B atoms on the polyhedral surface, and some new bi- and tri-metallic species were obtained. In addition, improved preparative routes to previously known systems were found. A typical rearrangement process is illustrated in Figure 20. 

This was the first example of a facile, intra-molecular, metal polyhedral rearrangement in a transition metal-carbonyl cluster. Other work showed that related metal polyhedral rearrangements occur when the metal polyhedra are not well close-packed, as when they contain a hetero-interstitial atom, e.g. [Rh9E(0O)2 (E = P or As), [RhioE(00)22]" (n = 3, E = P or As n = 2,... 

This process corresponds to the diamond-square portion of the diamond-square-diamond process involved in polyhedral rearrangements. For example, rupture of six edges in this manner from an icosahedron can give a euboetahedron as follows ... 

Several high-nuclearity rhodium clusters are observed to undergo polyhedral rearrangements on the NMR timescale at ambient temperatures and some gold clus-... 

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