Sulfur rich complexes

It has been suggested that the use of zinc dithiolate complexes as vulcanization catalysts may be closely related to the ability of these complexes to form sulfur-rich complexes that have very labile disulfide sulfur atoms (230). 

It was proposed that the formation of the sulfur-rich species M(R2dtc>3S takes place via the activated complex... 

The chemistry of the dithiocarboxylate complexes of nickel (II) has been investigated extensively. Interest in recent years has been mainly in the further investigation of the "sulfur-rich species, the perthiocarboxylates, and the unusual structures discovered in the dithiocarboxylate complexes (359). The violet complex formed by reaction of [Ni(C H5CS2)2] with sulfur or polysulfide, [Ni(CgHsCS2)2]2, origi-... 

Sulfur-Rich Polysulfides with Complex Univalent Cations. 132... 

The chemistry of elemental sulfur and sulfur-rich molecules including polysulfides in liquid ammonia [82] and in primary as well as secondary amines [83] is complex because of the possible formation of sulfur-nitrogen compounds. Therefore, polysulfide solutions in these solvents will not be discussed here. Inert solvents which have often been used are dimethylfor-mamide (DMF) [84-86], tetrahydrofuran (THF) [87], dimethylsulfoxide (DMSO) [87], and hexamethylphosphoric triamide (HMPA) [86, 88]. 

The sulfur-rich oxides S 0 and S 02 belong to the group of so-called lower oxides of sulfur named after the low oxidation state of the sulfur atom(s) compared to the best known oxide SO2 in which the sulfur is in the oxidation state +4. Sulfur monoxide SO is also a member of this class but is not subject of this review. The blue-green material of composition S2O3 described in the older literature has long been shown to be a mixture of salts with the cations S4 and Ss and polysulfate anions rather than a sulfur oxide [1,2]. Reliable reviews on the complex chemistry of the lower sulfur oxides have been published before [1, 3-6]. The present review deals with those sulfur oxides which contain at least one sulfur-sulfur bond and not more than two oxygen atoms. These species are important intermediates in a number of redox reactions of elemental sulfur and other sulfur compounds. 

Zinc is the active metal in the largest group of metalloproteins found in the nature. Recently a new class of zinc enzymes with a sulfur-rich environment has emerged the thiolate-alkylating enzimes, the most prominent of which is the cobalamine-independent methionine synthase.126 For these reasons several monothiolate zinc complexes have been prepared for the modelling of these enzymes with different N2S as (13),127 130 N20,13° 132 N3,132,133 S3,134 tripod ligands, or with Cd because of the favourable spectroscopic properties with an S3 tripod ligand.135... 

The use of six equivalents of dihydrogen peroxide leads to a clean conversion of the dithiolate complex to the disulfonate compound. Earlier studies on oxidation of nickel thiolates showed that oxidations with dioxygen stop at monosulfinates. Our observation and the characterization of the first chelating bis-sulfonato nickel complex formed from the direct oxidation of a mononuclear nickel dithiolate, may also provide new insight into the chemistry of sulfur-rich nickel-containing enzymes in the presence of oxygen. 

Thioneins are apoproteins that are exceptionally sulfur-rich (composed of greater 30 mol% cysteine). These proteins are found in high abundance in liver and kidney cytoplasm where they form metallothioneins (the holo-protein forms) upon complexation with metal ions. Thi-onein synthesis is induced by the presence of metals, especially zinc, copper, mercury, and cadmium. 

N NMR spectroscopy, 32 364-365 heterometallic cluster synthesis by nitrosylation of performed heterometallic aggregates, 32 350-351 from sulfur-rich metal complexes, 32 352-353... 

Apart from these I- I interactions, S- - S is one of the intermolecular contacts most frequently observed in gold complexes. Sulfur-rich dithiolate ligands having a planar geometry, such as C3S52 [4,5-disulfanyl-l,3-dithiole-2-thionate] or C8H4S82-[2- (4,5-ethylenedithio)-l,3-dithiole-2-ylidene -l,3-dithiole-4,5-dithionate], have been... 

All of these sulfur-rich derivatives are square planar complexes of nickel(II) as found in the X-ray crystal structures of [Ni(S3CPh)2] (284)2093 and [Ni(S3CR)(S2CR)] (285).2094... 

The infrared spectra of several M(ArDta)2 complexes (M = Ni, Pd, Pt, Zn Ar = Ph, Tol) and their sulfur-rich products M(ArDtaS)2 and M(ArDtaXArDtaS) have been obtained from 200 to 4000 cm 1 (92). 

Selected Structural Parameters of the Sulfur-Rich 1,1-Dithio Complexes. 

Similar conclusions were reached in another study, where an extensive tabulation of the electronic spectra of the dithio- and perthiocarboxylate Ni(II) complexes was presented (258). Recently it was reported by McCleverty and Morrison (440) that the reaction between Ni(//-p-MePhDtc)2 and n-Bu4 N(Me2 -Dtc) affords Ni(Me2Dtc)2 and the yellow crystalline Ni(//-p-MePhDtcS)2 complex, which contains the sulfur-rich trithiocarbamate ligand. 

Synthesis from Sulfur-Rich Metal Complexes... 

Dithiolenes can serve quite well as bridging ligands (see compound 43). A regular dithiolene ligand has also been shown to coexist in a binuclear complex with a bridging one the sulfur rich dithiolene28 Mo2(S2)(S2C2Ph2)4, cited earlier in a different context, is an example of this type of coexistence. 

---