Two new pi-conjugated 1,3-dithiol-2-ylidene-containing ligands, 4,5-[1',4']dithiino[2',3'-b]quinoxaline-2-bis(2-pyridyl)methylene-1,3-di thiole (L-1) and 4,5-bis(methylthio)-2-bis(2-pyridyl)methylene-1,3-dithiole (L-2), have been synthesized and characterized. Using L-1, L-2, or dimethyl 2-[di(pyridin-2-yl)methylene]-1,3-dithiole-4,5-dicarboxylate (L-3) as the auxiliary ligand and [(Tp)Fe(CN)(3)(-) or [(i-BuTp)Fe(CN)(3)(-) [Tp = tris(pyrazolyl)borate; i-BuTp = 2-methylpropyltris(pyrazolyl)borate] as the building block, two rectangular-square Fe2Ni2 clusters [(Tp)Fe(CN)(3)-Ni(L-1)(2)](2)center dot 2ClO(4)center dot 6H(2)O (1) and [(i-BuTp)Fe(CN)(3)Ni(L-3)(2)](2)center dot 2ClO(4)center dot 6H(2)O (2) and two trinuclear clusters [(Tp)(2)Fe-2(CN)(6)Ni(L-2)(2)]center dot 8H(2)O (3) and [(TP)(2)Fe-2(CN)(6)Co(L-3)(2)]center dot 5H(2)O (4) have been prepared in parallel and structurally characterized. Complexes 1 and 2 show similar square structures, and weaker intermolecular pi-pi-stacking interactions through the pyrazolyl groups of the Tp(-) ligands are observed. 2D sheet structures are formed in complexes 3 and 4 through intermolecular pi-pi-stacking interactions. In 3, shorter S center dot center dot center dot S contacts further connect the 2D sheets to 3D supramolecular structures. Magnetic studies show intramolecular ferromagnetic coupling in complexes 1-4. Complexes 1 and 2 show obvious frequency dependencies in the alternating-current magnetic susceptibility data, indicating single-molecule-magnet behavior with effective spin-reversal barriers of 8.7 K for 1 and 13.5 K for 2, respectively.