bis(2-chloroethyl)selenide bis(2-chloroethyl)selenide bis(2-chloroethyl)selenide is the organoselenium compound with the formula se(ch2ch2cl)2. as a haloalkyl derivative of selenium, it is an analogue of bis(2-chloroethyl)sulfide, the prototypical sulfur mustard used in chemical warfare. bis(2-chloroethyl)selenide has not been used as a chemical warfare agent, however it is still a potent alkylating agent and has potential in chemotherapy. selenium mustard names preferred iupac name 1-chloro-2-ethane identifiers cas number 4730-83-0 3d model (jsmol) interactive image chembl chembl288408 chemspider 23134672 pubchem cid 14699165 inchi inchi=1s/c4h8cl2se/c5-1-3-7-4-2-6/h1-4h2key: ffmukndyulfljk-uhfffaoysa-n smiles c(ccccl)cl properties chemical formula c4h8cl2se molar mass 205.98 g·mol−1 appearance low-melting colorless solid melting point 24 °c (75 °f; 297 k) except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). infobox references