Square-planar metal dithiolene complexes (M = Ni, Au) exhibiting cis and trans forms based on structurally flexible o-xylylene backbone

Article abstract of DOI:10.1016/j.poly.2012.08.026

The square-planar metal dithiolene complexes of o-xylenediyldithioethylene- 1,2-dithiolate (oxddt) ligand, (Et₄P)[Ni(oxddt)₂] (1), (Ph₄P)[Ni(oxddt)₂] (2) and (Ph₄P)[Au(oxddt) ₂] (3), were prepared and characterized. Among them, the Ni complexes 1 and 2 showed cis-anti-form structures, whose two benzene rings of the Ni(oxddt)₂ molecule are closely located to the dithiolene rings but located on the opposite side with respect to the dithiolene ring. In contrast to these Ni complexes, the Au complex 3 has a trans-anti form, suggesting that a Ni/Au substitution in the [M(oxddt)₂] modifies those molecular structures in the crystals. An intramolecular π orbital overlap at the α-LUMO + 5 level between benzene and dithiolene rings was observed in the [Ni(oxddt)₂] complex with the cis-anti-form. Redox behavior of 1 and 3 were investigated by cyclic voltammetry measurements.