Cyclometallation reactions, which allow the activation of C-H, C-C or C-F bonds, are noteworthy since these bonds present a large energy of dissociation and therefore a very limited chemical reactivity. Figure 2 shows examples of C-H, C-C and C-F intramolecular activations. The intramolecular C-H activation reactions at Pd(II) and Pt(II) complexes have been extensively studied. In the case of Pd(II), the intramolecular C-H activation (cyclopalladation reaction) takes place by an agostic interaction and with the help of an internal base, usually an acetato ligand (Figure 3). This is called "the electrophilic mechanism". Platinum(II), in function of its coligands, can activate C-H bonds by the "electrophilic mechanism" or by an oxidative addition mechanism. Figure 3 gives examples of cyclo-palladation and -platination reactions, which take place through the "electrophilic mechanism" or by the oxidative addition mechanism.

The reactivity of the cyclometallated compounds of the platinum group metals has been extensively studied. These compounds have a reach reactivity and can react with Lewis bases (Figure 4), nucleophiles and electrophiles and experience oxidative addition, insertion and reductive elimination reactions. The reactivity of the sigma metal-carbon bond or that of the metallic centre of cyclometallated compounds of the platinum group metals, especially those of Pd(II) and Pt(II), has allowed the preparation of new organic or organometallic compounds, such as those shown in Figure 5.