Polysulfide ligands metal complexes

Reactions of metal halides with polysulfide dianions are useful methods for the synthesis of polysulfido complexes of main group elements and transition metals. In most of these reactions, similarly to other methods, the chain lengths and coordination types of the polysulfide ligands depend on the other ligands coordinated to the metal, on the ratio between the metal and sulfur, on the reaction temperature, and other parameters. 

Draganjac M, Rauchfuss TB (1985) Transition metal polysulfides Coordination compounds with purely inorganic chelate ligands. Angew Chem Int Ed Engl 24 742-757 DuBois MR (1989) Catalytic applications of transition metal complexes. Chem Rev 89 1-9 Ansari MA, Ibers JA (1990) Soluble selenides and tellurides. Coord Chem Rev 100 223-266... 

Reaction of metal complexes with S is a convenient method for directly introducing the ligand by substitution of other ligands. For example, NajS2 or polysulfide solutions can be used for this purpose (77, 107, 108, 120,146). 

Polyrotaxene complexes, 46 271-273 Polysilanes, mass spectra of, 18 251 Polysilazanes, preparation of, 6 265-272 Polysiloxanes, 42 149-150 Polysulfide metal complexes, 31 89-122 cluster structures, 31 96 compound types, 31 91-103 with coordinated polysulfide ligands, 31 91-97... 

Complexes with chelating polysulfide ligands can be made either by reacting complex metal halides with solutions of polysuifides or by reacting hydiido complexes with elemental... 

Polysulfides of several metals can be prepared by reaction of the metals with excess sulfur in liquid NH3 (group IA metals) or by heating sulfur with the molten metal sulfide. The polysulfide ion binds to metals to form coordination compounds in which it is attached to the metal by both sulfur atoms (as a so-called bidentate ligand). One example is an unusual titanium complex containing the S52-ion that is produced by the following reaction (the use of h to denote the bonding mode of the cyclo-pentadienyl ion is explained in Chapter 16) ... 

The metal-ligand interaction in S complexes should he comparable to that in other complexes with sulfur-containing ligands, at least for higher values of n. Additionally, the observation that polysulfides with even n prefer coordination to closed-shell metal ions and those with odd n to open-shell ones indicates that the kind of metal-to-ligand interaction is obviously not restricted to the sulfur atoms attached directly to the metal. 

Bicyclo(4.4.1 Jundecapentaene complexes with group VI B metals, 12 237 Bidentate ligands, reactions with tetracyano complexes containing oxo or nitrido ligands, 40 310-313 Bidentate oligopyridines, 30 72-73 Bidentate polysulfide complexes, bond lengths, 31 114... 

The poly sulfides are most stable in alkaline waters, and for 2S(aq) = 10 mol/kg they predominate over HS above pH 8 (Fig. 12.15). Polysulfide ions are soft ligands that can be expected to form strong complexes with soft or borderline soft metal cations however, stability data for such complexes are lacking. Organically bonded polysulfides are important constituents in the pore waters of modern sediments (Boulegue et al. 1982). 

The polysulfide species [Mo=S(S4)2] (20 in Scheme 2.19) was reported to react with an alkyne producing a metal dithiolene unit in situ. The metal insertion reaction proceeds via electrophilic attack by dimethylacetylene-carboxylate (DMAC). It was observed that replacing the sulfido ligand with an 0X0 makes the tetrasulfide ligand less reactive towards the electrophilic attack by DMAC and changes the product of the reaction of DMAC and complexes possessing a Mo(S4) as shown in Scheme 2.19. 

---