Synthesis, structure, spectra, magnetism, non-linear optical properties and DFT calculations of a bis(dithiolene)nickel(III) anion salt with substituted isoquinolinium

Self-assemble of the bis(maleonitriledithiolate)nickel(III) anion ([Ni(mnt)₂]⁻) and 4-cyanobenzyl isoquinolinium cation ([4CNBzIQl]⁺) results into a new molecular solid, [4CNBzIQl][Ni(mnt)₂](1). Single crystal X-ray diffraction revealed that contains segregated columns of anions and cations and the Ni(III) ions form a 1 D zigzag alternating chain through Ni···S and π···π interactions between anions. Powder XRD diffraction study confirms the crystalline nature of the title material. The UV-Vis spectral analysis was used to determine the band gap energy, and the nonlinear optical (NLO) effect of the compound was predicted using DFT. Upon the temperature is lowered, the non-uniform chain has been compressed with the change of Ni···Ni distance, and a spin gap transition around 128 K.