Iron complexes xanthates

A number of iron(III) xanthates and thioxanthates have been prepared (1). The structure of the predominantly low-spin [Fe(Rxant)a] (R = Et, or SBu) complexes show features (246, 252) of coordination about the iron atom that are significantly different from those of [Fe(Bu2dtc>3], and it is estimated that there is 10-30% of double-bond character in coordinated S2CX (X = OR, or SR), which is appreciably... 

Whilst little information is available concerning iron(II) xanthates, the preparations of [Fe(S2COEt)j] and [Fe(S2COEt)3] have been described and addition of potassium xanthate to a solution of FeCl2 and 1,10-phenanthroline (2 1 1 ratio) yields [Fe(S2COEt)2(phen)]. If 1,10-phenanthroline is replaced by 2,2 -bipyridine, two crystalline modifications of [Fe(S2COEt)2(bipy)] are formed. Pyridine reacts with iron(III) xanthates to form high-spin iron(II) complexes as in equation (76),... 

Vinyl acetate is the monomer that has required significant efforts in order to achieve LRP. The first successfiil attempt was using RAFT with xanthates as a RAFT agent (also known as MADIX). At a later stage it turned out that certain dithiocarbamates also were able to induce LRP of vinyl acetate. Of all the attempts to pol5unerize VAc using ATRP, only specific iron complexes used by Sawamoto and co-workers were claimed to be successful (61). However, the PDIs they claimed were relatively large compared to other monomer/catalyst combinations. 

Pyridazines form complexes with iodine, iodine monochloride, bromine, nickel(II) ethyl xanthate, iron carbonyls, iron carbonyl and triphenylphosphine, boron trihalides, silver salts, mercury(I) salts, iridium and ruthenium salts, chromium carbonyl and transition metals, and pentammine complexes of osmium(II) and osmium(III) (79ACS(A)125). Pyridazine N- oxide and its methyl and phenyl substituted derivatives form copper complexes (78TL1979). 

Janetski et al. (1977) also studied the behavior of a pyrite electrode in a solution of cyanide concentration in the absence and presence of xanthate using voltammetric technique. They reported that on increasing the concentration of cyanide at constant pH and xanthate concentration, the oxidation wave of xanthate is shifted to more anodic potential indicating that the presence of cyanide, which may react with the mineral surface to form an insoluble iron cyanide complex will result in the inhibition of the electrochemical oxidation of xanthate and the depression of pyrite. 

As with earlier sections, there is a lack of structural data on binary xanthates for iron, ruthenium, and osmium, but there are a relatively large number of mixed-ligand complexes, particularly organometallic species. 

There are a number of dithio hgands, which readily form complexes with iron, the principal of which are dithiolates (55), dithiocarbamates (56), dithioacetylacetonates (57), xanthates (58), and dithiophosphates. 

Pyridazine forms a stable adduct with iodine, with semiconductor properties. " Similar complexes were prepared from iodine mono-ehloride, bromine, and nickel(II) ethyl xanthate. Complexes of pyrida-zines with iron carbonyls and with iron carbonyls and triphenylphosphine have been prepared and investigated. " Complexes of pyridazines with boron trihalides, silver salts, mercury(I) salts, iridium salts, " ruthenium salts, and chromium carbonyls are re-... 

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