Structure and characterisation of [Pt(Me2pipdt)2][Pt(mnt)2]2 and its unusual magnetic properties associated with a non-regular one-dimensional [Pt(mnt)2] stack

For electro-oxidation of [Pt(Me2pipdt)2][Pt(mnt)2] (Me2pipdtN,N′-dimethyl-piperazine-2,3-dithione; mnt = maleonitrile-2,3-dithiolate) (1a) the novel salt [Pt(Me2pipdt)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) Å [3.60(1) Å is the Pt⋯CC(mid point) separation] and 3.643(5) Å [3.980(3) Å 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.