Metallosupramolecular complexes derived from bis(benzene-o-dithiol) ligands

Contrary to its catechol analogue, the 1,5-naphthalenediamido-bridged bis(benzene-o-dithiol) ligand H(4)-3 does not yield [Ti(4)L(6)](8-) clusters when reacted with Ti(4+) starting materials, but instead gives dinuclear, triple-stranded complexes of type [Ti(2)L(3)](4-). The molecular structures of such complexes differ depending on the size of the counterions employed. The formation of both meso complexes (Lambda,Delta or Delta,Lambda isomers) and of dinuclear triple-stranded helicates (Lambda,Lambda or Delta,Delta isomers) was observed. Molecular-modeling calculations show energetically close minima for the meso complex and the corresponding helicate. In spite of the structural differences in the solid state, proton NMR spectra reveal C(3) symmetry for all three complex anions. Metal-donor interactions mainly dictate the coordination behavior, whereas the topology of the ligand has less influence. In addition, the dinuclear complex [Ti(2)(8)(3)](4-) with the unsymmetrical bis(benzene-o-dithiol) ligand H(4)-8 has been prepared. The unsymmetrical ligand can lead to four different stereoisomers when forming dinuclear triple-stranded complexes of type [Ti(2)(8)(3)](4-), two of which have been observed in solution.