Trans-influence in complexes

Approximate density functional theory calculations have been used to investigate the irons influence in [Os(N)(X)4] (X = Cl, Me, SMe) and [Os(N)(Cl)5] ". By using the transition state method the relative effects of steric and electronic stabilization on the trans influence in these complexes have been quantitatively assessed. It is found that the electronic stabilization is greater than the steric stabilization for these complexes. 

The evidence cited previously shows clearly that there is a trans influence in square planar complexes and that the magnitude depends on the nature of the ligand. In fact, the trans directing influence is a factor of major importance in the structures and substitution reactions of square planar complexes. It is now necessary to provide an explanation of how this phenomenon is caused and how it is related to the nature of the ligands. 

Table 3 NQR data illustrating cis and trans influences in halo complexes...

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