Polysulfide, coordination compounds

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... 

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 nse of polysnlfide complexes in catalysis has been discnssed. Two major classes of reactions are apparent (1) hydrogen activation and (2) electron transfers. For example, [CpMo(S)(SH)]2 catalyzes the conversion of nitrobenzene to aniline at room temperature, while (CpMo(S))2S2CH2 catalyzes a number of reactions snch as the conversion of bromoethylbenzene to ethylbenzene and the rednction of acetyl chloride, as well as the rednction of alkynes to the corresponding cw-alkenes. Electron transfer reactions see Electron Transfer in Coordination Compounds) have been studied because of their relevance to biological processes (in, for example, ferrodoxins), and these cluster compounds are dealt with in Iron-Sulfur Proteins. Other studies include the use of metal polysulfide complexes as catalysts for the photolytic reduction of water by THF and copper compounds for the hydration of acetylene to acetaldehyde. ... 

The data given in Table VI for removal of arsenic, cadmium, and lead using polysulfide were almost twice that obtained with sulfide at the lower treatment levels. This higher response to polysulfide may be due to the lower solubility of the polysulfide salts, coordination compounds having lower solubilities, or the polysulfides may simply furnish higher effective sulfide concentration. The stoichiometry of the precipitated material was not determined in these tests. 

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... 

From the reaction of Au with alkali metal polysulfide liquids, LiAuS and NaAuS were discovered. Both compounds contain infinite one-dimensional (AuS) chains, featuring alternating sulfide anions and linear coordinated Au centers. In LiAu8, the chains are zigzag and fully extended and they pack in mutually perpendicular sets. In NaAuS, the same chains coil in an unusual fashion so that they become interwoven to form layers reminiscent of chicken-wire (Figure 17). This novel coiling mode allows Au Au contacts to form, which help to stabilize the structure. 

Under anoxic conditions, the speciation of cadmium is dominated by coordination with reduced sulfur compounds including sulfide and polysulfides. In sediments, the solubility of Cd must be controlled by its adsorption on oxides or the formation of minerals CdCOs under oxic conditions and CdS under anoxic conditions [24]. The high affinity of Cd for the surface of... 

Polarization infrared spectral data. X-ray analysis and normal coordinate treatment revealed the stable molecular conformation of poly(methylene disulfide) to be the GG G form [88] which was also confirmed from the results of semi-empirical CNDO/2SCF MO calculations [89]. Poly(ethylene disulfide) was also found to exist in a similar conformation as that of poly(methylene disulfide) [90]. Under vacuum at 50 °C, polysulfide polymers of methylene and ethylene with sulfur rank of two and four were exposed to UV radiation [91]. While poly(methylene disulfide) and poly(methylene tetrasulfide) yielded polymeric carbon monosulfide, hydrogen sulfide and carbon disulfide as the major degradation products, the ethylene counterparts produced the same compounds except carbon disulfide. The tetrasulfide polymers also formed volatile products which on condensation gave the original polymer. 

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