Metallaborane isocloso

A comprehensive summary of the theoretical contributions over the past 40 years towards the understanding of the relationship between two-dimensional aromaticity (hydrocarbons) and the electronic structure of three-dimensional deltahedral boranes. Note in particular that rearrangement processes and the isocloso problem in metallaboranes have also been discussed.11... 

The development of metallaborane chemistry in recent years has led to the discovery of some metallaborane structures containing the so-called isocloso deltahedra, which have a transition metal atom (e.g., Ru, Rh, Ir) located at a degree 6 vertex. Such isocloso metalla-borane dehahedra, except for the 11-vertex structures, are topologically different from the closo borane deltahedra foimd in the simple boranes and the... 

II.D). Thus, consider the bonding topology in a an isocloso metallaborane deltahedron with n vertices, which can be shown by Euler s theorem to have 2/7 — 4 faces and 3/7 — 6 edges such as the corresponding closo deltahedron with the same number of vertices. If each vertex (e.g., a neutral BH vertex or isoelectronic/isolobal equivalent) contributes three skeletal (internal) orbitals and two skeletal electrons (i.e., a 2/7 skeletal electron system), then the numbers of skeletal orbitals and electrons are correct for 3c-2e bonds in n of the 2/7 — 4 faces leaving /7 — 4 faces without 3c-2e bonds. 

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