Superconductivity at ambient pressure in di[bis (ethylenedithio) tetrathiafulvalene]triiodide, ${\mathrm{}(\mathrm{B}\mathrm{E}\mathrm{D}\mathrm{T}-\mathrm{T}\mathrm{T}\mathrm{F})\mathrm{}}_2$${\mathrm{I}}_3$

Di[bis(ethylenedithio)tetrathiafulvalene]triiodide [${\mathrm{}(\mathrm{B}\mathrm{E}\mathrm{D}\mathrm{T}-\mathrm{T}\mathrm{T}\mathrm{F})\mathrm{}}_2$ ${\mathrm{I}}_3$] crystals in the form of distorted hexagon-shaped plates or blocks grown from 1,1,2-trichloroethane and in the form of needles grown from benzonitrile were found to be superconducting at ambient pressure below 1.40 ±0.02 K. rf penetration depth measurements of the critical temperature and critical field are described. ${\mathrm{}(\mathrm{B}\mathrm{E}\mathrm{D}\mathrm{T}-\mathrm{T}\mathrm{T}\mathrm{F})\mathrm{}}_2$ ${\mathrm{I}}_3$ is the first known sulfur-based, ambient pressure organic superconductor.