‘Unsymmetric’ palladium(II) complexes with ligand 4′,5′-diaza-9′-(4,5-disubstituted-1,3-dithiole-2-ylidene)-fluorene

Four ‘unsymmetric’ complexes of palladium(II), [Pd(L)Cl2] and [Pd(L)(dmit)], have been synthesized and characterized [L=4′,5′-diaza-9′-(4,5-bis(methylthio)-1,3-dithiole-2-ylidene)-fluorene (L1) and 4′,5′-diaza-9′-(4,5-ethylenedithio-1,3-dithiole-2-ylidene)-fluorene (L2)]. Single crystal structure of [Pd(L1)Cl2] was determined, in which, the atoms of the molecule, except two methyl-groups, are conjugated in a quasi-plane. The planar molecules are further stacked forming two unequivalent columns with C⋯C, S⋯C and S⋯Cl contacts. The differences between dichloro complexes and dmit complexes in IR, UV and oxidation properties were discussed in detail. The dmit complexes exhibit LLCT band from dmit (donor) to π* of L1 (acceptor).