A template-directed synthetic approach to halogen-bridged mixed-valence platinum complexes has been performed in organic media using, for instance, a synthetic peptide bearing two bis (ethylenediamine)-based Pt (IV) complexes with two axial bromide anionic ligands,[1a (Pt (IV) Br2 (en)) 2](RSO3) 4, and a [Pt (II)(en) 2](RSO3) 2 complex (R=(C12H25OCH2) 2CHO (CH2) 3–).