Three new types of dithiolene ligands have been prepared on the basis of Diels-Alder reactions of the diene 2,3-bis(benzylthio)-1,4-dichloro-5,5-dimethoxy-1,3-cyclopentadiene (4), whose structure was established by an X-ray structure determination. Reaction of 4 with excess norbornadiene as the dienophile affords the adduct 5, S-deprotection and dechlorination of which with sodium in liquid ammonia lead to the ligand-salt Na-2(L-S-2) (6). Treatment of 2 equiv of 4 with 1 equiv of norbornadiene gives the tetraprotected bis(dithiolene) 7, which is converted to the ligand salt Na-4(L-S-4) (8) by sodium in liquid ammonia. Reaction of 2-(chloromethyl)-1-(ethoxymethyl)benzimidazole with 1,4-dihydronaphthalen-1,4-imine gives the N-substituted imine dienophile 10. Reaction of the latter with 4 produces the adduct 11, which after deprotection affords the ligand salt Na-2-(L-NS2) (12). The endo,exo ligand stereochemical outcome of the Diels-Aider reaction was proven by determination of the structure of [Ni(L-S-2)(2)] (13). This compound crystallizes in monoclinic space group P2(1)/n with a = 7.636(2) Angstrom, b = 8.64(4) Angstrom, c = 20.962(4) Angstrom, beta = 96.57(2)degrees, and Z = 2. The complex is planar and centrosymmetric.