Transition metal dithioacetylacetonates
Transition metal dithioacetylacetonates are coordination complexes containing dithioacetylacetonate 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 M3 and M2. Mixed-ligand complexes are also known, e.g..
Synthesis
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.Examples
Square planar complexes of the type M2 are known for Ni, Pd, Pt, Co. Tetrahedral M2 are isomorphous for M = Mn, Zn, Cd. In contrast with these structures, M2 are dimers or oligomeric for M = Co, Ni, Mn, Cd, Zn. The octahedral complex Fe3 is low-spin, in contrast to Fe(acac)3.Complexes are also well known for monothioacetylacetone. The free ligand is readily obtainable as a distillable liquid, which facilitates the preparation of these coordination complexes. Fe3 exhibits spin crossover behavior.