High Ambipolar Mobility in a Neutral Radical Gold Dithiolene Complex

Abstract

AbstractA new anionic gold dithiolene complex NBu4·[1] is synthesized from the (1‐((1,1‐biphenyl)‐4‐yl‐)‐ethylene‐1,2‐dithiolene ligand 1, and the cis and trans isomers are separated by recrystallization. The trans isomer is oxidized via electrocrystallisation to the neutral gold dithiolene complex 2. Complex 2 crystalizes in 1D chains, held together by short (3.30–3.37 Å) S–S contacts, which are packed in a herringbone arrangement in the ab‐plane. The complex exhibits semiconductor behavior (σRT = 1.5 × 10−4 S cm−1) at room temperature with a small activation energy (Ea = 0.11 eV), with greater conductivity along the stacking direction. The charge transport behavior of complex 2 is further investigated in single‐crystal field‐effect transistor (FET) measurements, the first such measurements reported for gold dithiolene complexes. Complex 2 shows incredibly balanced ambipolar behavior in the single‐crystal field‐effect transistor (SC‐FET), with high charge‐carrier mobilities of 0.078 cm2 V−1 s−1, the highest ambipolar mobilities reported for metal dithiolene complexes. This well‐balanced behavior, along with the activated conductivity and band structure calculations, suggests that 2 behaves as a Mott insulator. The magnetic properties are also studied by superconducting quantum interference device (SQUID) magnetometry and solid state 1H NMR, with evidence of a nonmagnetic ground state at low temperature.