Biological processes transition elements essential

The inertness snggests the reason that Mo is the only essential transition metal fonnd in biological systems that is not a first-row transition metal. Most second- and third-row transition metals appear to be too strongly bound and inert to engage in metabolic processes (Hoeschele et al. 1991). However, the inertness of some second- and third-row elements, such as Pt(II), can be useful for the chemotherapeutic activity of these complexes. The inertness probably plays a role also in the mutagenicity and mild carcinogenicity observed for cisplatin and the mutagenicity of other inert complexes, especially Cr(III) complexes. 

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