Ligands metal fragments

Fig. 8. Potential energy surfaces for ligand addition. Case (c) weakly repulsive potential energy surface for approach of the incoming ligand to the high-spin metal fragment.

Coordination is further promoted by secondary donor-acceptor interactions between orbitals of the metal fragment and the ligand. Representative examples of such interactions are shown in Fig. 4.35 for the special case of H2W(NH3)2 (cf. Fig. 4.33(b)). 

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