A compact planar low-energy-gap molecule with a donor-acceptor-donor nature based on a bimetal dithiolene complexElectronic supplementary information (ESI) available: Synthetic procedures, 1H-NMR spectra, X-ray crystallographic information, TG analysis, temperature dependence of structural change obtained from the results of single crystal X-ray diffraction using a high intensity X-ray source in SPring-8, variable temperature measurements of resonance Raman spectroscopy, DFT calculations, absorp

We present the first report of a compact, planar and low-energy-gap molecule based on a π-conjugated bimetal system comprising a tetrathiooxalate ( tto ) skeleton. The observed low HOMO-LUMO energy gap (1.19 eV) is attributed to its donor-acceptor-donor (D-A-D) nature because the tto skeleton acts as an electron acceptor as well as a tiny and noninnocent bridging moiety. We prepared a compact, planar, low-energy-gap molecule with donor-acceptor-donor (D-A-D) nature for the first time based on a bimetal dithiolene complex.