Synthesis, spectroscopic characterization and solid-state electrical behavior of [Ni(L)2] [L = 1,2-di(4-methoxyphenyl)ethene-1,2-dithiolate]: a computational investigation on UV–vis-NIR absorption and electrical transport

Abstract

A bis(dithiolene)nickel(II) complex, [Ni(L)2] (1) [L = 1,2-di(4-methoxyphenyl)ethene-1,2-dithiolate], has been synthesized and characterized using elemental analysis, UV–vis-NIR, IR, NMR spectroscopies and high resolution mass spectrometry. The geometry of the molecule was optimized using density functional theory (DFT) calculations. The calculated bond angles and distances are in agreement with the literature value. As for other dithiolenes, the present molecule absorbs extensively at 925 nm, in the near-infrared (NIR) region. A time-dependent density functional theory (TD-DFT) predicts the absorption at 1002 nm. The other absorptions are in better parity with the experimental values. In solid-state, 1 conducts electricity. The electrical conductivity of 1 rises on increasing temperature. Upon incremental changes of temperature to 200 °C, the solid-state electrical conductivity of 1 reaches 1.91 × 10−4 S/m. From electrical conductivity versus temperature plot, it is clearly found out that 1 behaves like a semiconductor. The band gap of the molecule was calculated using DFT. The calculated band gap for 1 is 0.0724922 eV which indicates that 1 deviates from metallic to semiconductor-like behavior. The thermal stability of the molecule reveals that the molecule is thermally stable to 200 °C. This is why the temperature variance of the molecular electrical conductivity was measured to this temperature.