Sulfides anionic ligands

The predominance limits shown in figure 8.22 are analytically summarized in table 8.17. Compare figures 8.22 and 8.21 to better visualize the redox state of the anionic ligands at the various Eh-pH conditions of interest (particularly the sulfide-sulfate transition and carbonate limits). We remand to Garrels and Christ (1965) for a more detailed account on the development of complex Eh-pH diagrams. 

These effects are particularly pertinent in type (I) -> (II) reactions, where the high anion activity is required to overcome the lattice energy of the non-molecular precursor (I). Thus many non-molecular metal halides, sulfides and thiolates which are insoluble and unreactive in aqueous media will dissolve with anionic ligands in aprotic solvents, and clusters can be isolated from the resulting solutions. Anion activation by use of cation complexands to solubilize salts in hydrocarbon solvents is advantageous, as is the use of complexands in the isolation of polymetallate anions.342... 

Fig. 2.2 shows the adsorption spectra of a colloidal CdS solution prepared by the above method in the presence of cadmium complexones of various nature. The position of the colloids adsorption band indicates that the equilibrium size of the colloidal particles decreases as the stability constant of the complex increases. This may relate to the fact that it is precisely the decay rate of the cadmium complex that determines the number of nuclei N and, hence, the size of the forming particles. This is supported by the fact that with the fixed initial (before the addition of the sulfide anion and after the addition of the ligand) concentration of activated Cd2+ (lg[CdL]/[Cd2+]) = const and [Cd°] = const), for complexones of various nature, the sizes of colloidal particles differ the stronger the initial complex, the smaller the particle size. 

Dibenzyl trisulfide provides a useful source of sulfur for the preparation of sulfide anions via oxidative replacement of R8 ligands (equation 38). [Fe2(/r-82)(85)2] contains two Fe85 rings bridged by two 8 anions. 

Many monomeric palladium(II) complexes of the type [PdX2(ER2)2] (X = wide variety of anionic ligand, E = S or Se, R = alkyl or aryl) have been prepared, generally by the reaction of the organic sulfide with an aqueous solution of Displacement of benzonitrile... 

M. N., Jones, P.G. and Erdhruegger, C.F. (1989) (Diphenylphosphinomethyl) diphenylphosphine sulfide (Ph2PCH2PPh2S) and its methanide anion Ph2PCHPPh2S- as ligands in organogold chemistry. X-ray crystal structure of [(diphenylphosphino) (diphenylthiophosphinoyl)methanido-P, S]his(pentafluorophenyl)gold(l 11). 

The anionic species ROCS2 resulted from O-alkyl(aryl) esters of the hypothetical dithiocarbonic acids, ROC(S)SH, better known as xanthates, are versatile ligands and they generate an extensive coordination chemistry. The interest for metal xanthates is stimulated by their potential use as single source precursors for nanoscopic metal sulfides in photochemical or thermal vapor deposition systems under mild conditions,218 221 e.g. for Zn,222 Cd,223 In,224... 

The reaction of bare metal ions with sulfur has received some attention. The reaction of metal ions with elemental sulfur (S8) was first studied by Freiser and his co-worker (110) in the study of Fe+ with S8. This reaction produced the ions [FeSJ+, where x = 1-10, which under collision-induced dissociation experiments were observed to undergo sequential loss of S2 units. It has been suggested that Fe(S2)5 + would result in the unreasonable oxidation state of Fe(XI) (9). The S2 unit is similar to the 02 molecule with two unpaired electrons and could act as a neutral ligand (not an anion S2 or dianion) and the oxidation state of Fe in the ion Fe(S2)5 + would be (I). Some similar ions have also been produced by the reaction of Fe+ with ethene sulfide, QH4S. The results for Fe+ have now been confirmed in a study of all the transition metals cations (except Tc+) reacting with gaseous sulfur (50, 150). The study shows that [MS4]+ was a common first major ion (some reac-... 

A full imderstanding of the speciation of dissolved iron requires consideration of ligands other than water and hydroxide. The most important ones are listed in Table 5.6 along with their concentration ranges in seawater and freshwater. For Fe(III) in seawater at pH > 4, the formation of complexes with hydroxide is most important, but at pH <4, sulfete, chloride, and fluoride pairing predominates (Figure 5.15b). To predict the equilibrimn speciation at low pH, these anions need to be added to the mass balance equation fiar Fe(III) (Eq. 5.20). Seawater with low pH tends to have low O2 concentrations. Under these conditions, most of the dissolved iron is present as Fe( II), which undergoes complexation with sulfide and carbonate. 

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