1,3-dithiol-2-ylidene derivatives of 1,3-indanedione

The synthesis is described of a series of mono-, bis-, and tris(1,3-dithiol-2-ylidene) derivatives 7, 9 and 10 starting from 1,3-indanedione. Cyclic voltammetric data establish that the pi-electron donor ability of these molecules increases in the sequence 7 < 9 < 10, which is consistent with stabilisation of the cationic species by the presence of additional 1,3-dithiole units. The X-ray crystal structure of a complex (7a)(2). TCNQ is reported. Short intramolecular S ... O contacts are observed within moiety 7a. The mean planes of 7a and TCNQ are almost parallel forming planar layers within which ribbons of TCNQ molecules are intercalated by double ribbons of molecule 7a all stretched along the x direction. (C) 1999 Elsevier Science Ltd. All rights reserved.