Transition metal dithioacetylacetonates are coordination complexes containing dithioacetylacetonate (, abbreviated SacSac<sup>-</sup>) as a bidentate ligand. Dithioacetylacetonate complexes are analogous to acetylacetonate complexes: both sulfur atoms bind to the metal to form a six-membered chelate ring. The simplest complexes have the formula M(SacSac)<sub>3</sub> and M(SacSac)<sub>2</sub>. Mixed-ligand complexes are also known, e.g. .
Dithioacetylacetone is well-characterized, so complexes are prepared by indirect methods. In one approach, a solution of acetylacetone is treated with a mixture of hydrogen sulfide and hydrochloric acid prior to the addition of a metal halide. SacSac complexes can also be prepared by reduction of a 1,2-dithiolium salt with sodium borohydride followed by treatment with a metal salt. A common unsymmetrical version of a HSacSac ligand is , which can be prepared from O-ethylthioacetate.
Square planar complexes of the type M(SacSac)<sub>2</sub> are known for Ni (red), Pd (red), Pt (violet), Co (violet). Tetrahedral M(SacSac)<sub>2</sub> are isomorphous for M = Mn, Zn, Cd. In contrast with these structures, M(acac)<sub>2</sub> are dimers or oligomeric for M = Co, Ni, Mn, Cd, Zn. The octahedral complex Fe(SacSac)<sub>3</sub> is low-spin, in contrast to Fe(acac)<sub>3</sub>.
Complexes are also well known for monothioacetylacetone (HSacac). The free ligand is readily obtainable as a distillable liquid, which facilitates the preparation of these coordination complexes. Fe(Sacac)<sub>3</sub> exhibits spin crossover behavior.