An Unsymmetrical Tripodal Ligand with NOS<sub>2</sub>-Donor Set:  Coordination Chemistry with Nickel(II) and Zinc(II)<sup>†</sup>

The synthesis of the novel tripodal ligand [N(CH<sub>2</sub>CH<sub>2</sub>CH<sub>2</sub>OH)(CH<sub>2</sub>CH<sub>2</sub>SH)<sub>2</sub>] H<sub>3</sub>-<b>4</b> is reported. The aliphatic tetradentate ligand is equipped with an unsymmetrical NOS<sub>2</sub> donor set. It reacts with Ni(OAc)<sub>2</sub>·4H<sub>2</sub>O or Zn(BF<sub>4</sub>)<sub>2</sub>·<i>x</i>H<sub>2</sub>O to give the complexes [Ni(H-<b>4</b>)]<sub>2</sub> <b>5</b> and [Zn(H-<b>4</b>)]<sub>4</sub> <b>6</b>, respectively. The molecular structures of <b>5</b> and <b>6</b> have been determined by X-ray diffraction. In both cases multinuclear, μ-thiolato-bridged complexes, wherein the ligand coordinates with only three (NS<sub>2</sub>) of the four donor groups, had formed. The dinuclear complex <b>5</b> adopts a butterfly geometry and contains nickel(II) ions in a square-planar NS<sub>3</sub> coordination environment. Cyclic voltammetry experiments indicate that the nickel centers in <b>5</b> are electron-rich but not overly sensitive toward oxidation. Complex <b>6</b> is tetranuclear and the four thiolato-bridged metal centers form a ring. It shows a distorted tetrahedral coordination geometry for the zinc(II) ions in an NS<sub>3</sub> coordination sphere. In both complexes the hydroxyl functionalized ligand arm of the tripodal ligand remains uncoordinated.