For electro-oxidation of (Pt(Me(2)pipdt)(2)][Pt(mnt)(2)] (Me(2)pipdt=N',N'-dimethyl-piperazine-2,3-dithione; mnt = maleonitrile-2,3-dithiolate) (1a) the novel salt [Pt(Mepipdt)(2)][Pt(mnt)(2)](2) (2a) has been prepared and characterised. 2a exhibits segregated chains of anionic and cationic complexes. The anions generate a non-regular stack with the separation between the planes of 3.558(5) angstrom [3.60(1) angstrom is the (PtC)-C-...=C-(mid point) separation] and 3.643(5) angstrom [3.980(3) angstrom is the separation between Pt and S-atoms]. The cations are perpendicular to the anions and interposed between those stacks in a ribbon fashion. Magnetic measurements show the presence of a magnetic transition between the behaviour of an antiferromagnetic alternating-exchange chain and the behaviour of a set of antiferromagnetic dimers. (c) 2006 Elsevier B.V. All rights reserved.