Octahedral-trigonal prism interconversions

The interconversion between octahedral and trigonal prismatic is of relatively high energy because an octahedron has 12 metal-metal bonds and a trigonal prism has only nine metal-metal bonds and, therefore, three bonds must be broken or formed. Such processes are quite rare and examples of reversible processes are limited to a few carbide clusters of the Group 9 metals. 

The octahedral trigonal prismatic rearrangement corresponds to a rotation of two triangular units by 60° relative to one another and three bonds must be broken (or formed). It is possible that the carbide atom in the above clusters enables this 

8 Polyhedral rearrangements of high-nuclearity osmium clusters 

Thermolysis of Os6(CO) g in butanol for 53 h affords several clusters, including the anion [HOs8(CO)22] in 30% yield.A single-crystal X-ray diffraction analysis of 

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