Assembled structures and magnetic properties of viologen-[M(mnt) 2] charge-transfer salts (mnt = maleonitriledithiolate; M = Cu, Ni, Pt)

Article abstract of DOI:10.1016/j.ica.2011.11.043

Ion-pair compounds of phenyl-substituted viologen dications with [M(mnt)₂] dianions were prepared and characterized. (Benzyl viologen)[M(mnt)₂] (M = Cu (1), Ni (2), Pt (3)) and (phenyl viologen)[Cu(mnt)₂] (4) exhibited mixed-stack crystal structures, whereas (dinitrophenyl viologen)[Cu(mnt)₂] (5) exhibited no π-π interactions. Magnetic susceptibility measurements revealed that 1 exhibits a ferromagnetic exchange interaction (Weiss constant θ = +0.9 K), possibly mediated by the diamagnetic cation. Antiferromagnetic interactions were observed for 4 (θ = -2.0 K) and 5 (θ = -2.9 K), whereas 2 and 3 were diamagnetic. Absorption bands assignable to charge transfer were observed in the mixed-stack salts in the visible to near-infrared region.