Polysulfide Chelates

At the turn of the century, Hoffman and Hochtlen1 2 reported on crystalline polysulfides of heavy metals. However, their directions were very brief and no chemical characterization nor plausable structures were presented. Our interest in inorganic heterocyclic rings led us to investigate these and new polysulfide chelates.3"5 Some of our detailed preparations are outlined here. 

The bonding properties of (Ti02) have been used for size-reinforcing of glass fibers so that they adhere to asphalt or to a PTEE—polysulfide mixture to impart enhanced flex endurance (434—436). Poly(vinyl alcohol) (PVA) solutions mixed with sucrose can be cross-linked with the lactic acid chelate and used generally for glass-fiber sizing (437). 

Complexes with chelating polysulfidc ligands can be made either by reacting complex metal halides with. solutions of polysulfides or by reacting hydrido complexes with elemental... 

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... 

The action of zinc in increasing the efficiency and rate of crosslinking is thought to involve chelation of zinc with the accelerator as well as species XVIII and XIX. Zinc polysulfide compounds such as XX are also likely intermediates. Zinc chelated to sulfur or as zinc sulfide bonds probably facilitate cleavage of sulfur-sulfur bonds in the concerted reactions described by Eqs. 9-20 and 9-21. 

Sulfur has a strong tendency to catenation, which manifests itself not only in the many forms of the element that all contain S rings of various sizes, but in polysulfide ions S - which may be discrete in highly ionic salts or serve as chelating ligands towards transition metals, sulfanes (XS X) (where X... 

The complex is obtained as dark-red crystals insoluble in water. The structure5 is different from that of other polysulfide complexes in that it consists of non-chelated S6 chains linking planar palladium(II) ions. Chains appear to abort in their growth from the palladium, giving a defect structure accounting for the unusual formula. 

The presence of the pyramidal [M(82)2E] (E=0, 8) intermediate seems to be a general feature in the acidification of M84, since this fragment was also trapped and characterized with [V04] " in a polysulfide-containing medium. This intermediate readily reacts with chelating ligands and is stabilized as a mononuclear spe-... 

The new complex anion [PtSi8]2- gave (31) a crystalline salt with the tetraphenyl-phosphonium ion. The anions were [Pt(S6)3]2 , with three seven-membered chelate rings the angles within the rings, 8-Pt-8, were much larger than 90 . These systems containing platinum ions complexed by polysulfides are thus chemically rather more complicated than expected. 

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