Crystal structures and dielectric properties of two salts of nickel-bis-1,2-dithiolene with noncentrosymmetric organic cations

Two nickel-bis-1,2-dithiolene salts, [1,4-dimethyl-DABCO][Ni(mnt)2] (1) and (TMSF)2[Ni(mnt)2] (2) (mnt2− = maleonitriledithiolate, 1,4-dimethyl-DABCO2+ = 1,4-dimethyl-1,4-diazoniabicyclo[2.2.2]octane and TMSF+ = trimethylsulfonium) were synthesized and characterized by single crystal structures. The two salts show similar packing structure and display analogous dielectric behavior and two steps of dielectric relaxations in the higher temperature regime.