Integral, Closed Shell, and Restricted Chemistry

Multicenter, Integral, Closed Shell, and Restricted Chemistry 

There is a variety of chemical species whose constitution cannot be adequately described in terms of electron pair bonds between pairs of cores. Examples are the boron hydrides, the transition metal complexes of hydrocarbons and their anions, such as Tt-allyl nickel or ferrocene, or the hypothetical intermediate of the limiting Sjy mechanism 88). In these cases the molecular structure can be adequately represented by the model concepts of imdlicenter bonds and fractional bond orders. 

EM with fractional bond orders can be represented by fe-matrices having rational entries. The off-diagonal entries are 

Even if only inadequate information on the chemical constitution of a species is available, the double bookkeeping properties of 6 -matrices avoid serious errors in the algebra of the rational 6e-matrices and their reaction matrices. 

For example, the chemical constitution of diborane is rather described by 6 than by 7, 

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