Palladium(II) pincer complexes of N-(thiophosphorylalkyl)picolinamides: effect of the length of the P^V-pendant arm on the cytotoxic activity

A convenient synthetic route to β- and γ-thiophosphorylated alkylamines is suggested based on the nucleophilic substitution between the ω-bromoalkylamines and Ph₂PK followed by the addition of elemental sulfur. These functionalized phosphine sulfides are shown to serve as useful synthons for the new non-classical picolinamide-based pincer ligands. The cyclopalladated derivatives of the latter exhibit promising cytotoxic properties, which strongly depend on the length of the thiophosphoryl pendant arm.