Crystal and molecular structures of 2-dodecyl-7,7,8,8-tetracyanoquinodimethane

To develop a possible structural model for molecular arrangement in Langmui r-Blodgett (LB) films of 2-alkyl-7,7,8,8-tetracyanoquinodimethane (alkyl-TC NQ) the molecular and crystal structures of 2-dodecyl-7,7,8,8-tetracyanoqui nodimethane (dodecyl-TCNQ) have been determined by X-ray single-crystal ana lysis. The compound crystallizes in the triclinic space group P (1) over ba r with Z = 2. The molecule consists of the planar TCNQ moiety and the dodec yl chain having all-trans conformation. In the crystals the TCNQ fragments make a stacking structure in a head-to-head manner across the centers of sy mmetry to form a double layer of TCNQ groups. The dodecyl chains protrude o ppositely from the TCNQ layers and are assembled to form a close-packed lay er, being interdigitated with each other. In this way, the TCNQ moieties an d the dodecyl groups form layers alternately. This molecular arrangement in the crystal provides new insight into the structure of the LB films of alk yl-TCNQ.