Valence-shell electron-pair repulsion trigonal pyramidal

If an attempt were made to apply the rules of valence shell electron pair repulsion theory to radicals, it would not be clear how to treat the single electron. Obviously, a single electron should not be as large as a pair of electrons, but it is expected to result in some repulsion. Therefore, it is difficult to predict whether a radical carbon should be sp2 hybridized with trigonal planar geometry (with the odd electron in a p orbital), sp3 hybridized with tetrahedral geometry (with the odd electron in an sp3 AO), or somewhere in between. Experimental evidence is also somewhat uncertain. Studies of the geometry of simple alkyl radicals indicate that either they are planar or, if they are pyramidal, inversion is very rapid. 

Non-oxo pentacoordinated vanadium complexes can adopt the stmcture of a trigonal bipyramid [VF5 in accord with valence shell-electron pair repulsion (VSEPR) theory], or that of a square pyramid [predicted for ( 113)5]. ]... 

Valence shell electron pair repulsion (VSEPR) model Trigonal pyramid... 

Section 8.13 molecular structure valence shell electron-pair repulsion (VSEPR) model linear structure trigonal planar structure tetrahedral structure trigonal pyramid trigonal bipyramid octahedral structure square planar structure... 

This net is based on square planar pyramidal nodes and is less common than the bnn net (section 5.2.7) based on nodes with trigonal bipyramidal coordination. This is likely an effect of the fact that the trigonal bipyramid is slightly energetically favoured over the square planar pyramid in VSEPR (valence shell electron pair repulsion) theory [6]. 

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