Sulfur ligands antimony

Antimony has a great affinity for charged sulfur ligands which include thiolates, xanthates (R0CS2 ), dithiocarbamates (R2NCS2 ), and dithiophosphates ((RO)2PS2 ). In contrast to arsenic, where this chemistry is limited to oxidation state III, antimony forms compounds in oxidation states III and V. The xanthate, dithiocarbamate, and dithiophosphate complexes are mostly made by reaction of antimony(III) halides or organohalides with Na, NH4, or Ag salts of the acids. Complexes... 

Antimony(III) complexes with bidentate sulfur ligands form an interesting series of structural types. In tris(diethyldithiocarbamate)antimony(IIl) the sulfur atoms fall into two groups. Firstly, there are three fac sulfurs with short d(Sb—S) 2.487-2.631 A bonds, one from each ligand, and then there are three longer bonds d(Sh—S) 2.886-2.965 A (40). There is a large gap in the coordination sphere and this has been ascribed to a sterically active lone pair. There is a weak Sb- -S 3.389 A interaction between molecules within van der Waals radii. Similar results have been obtained for Sb(S2CNPr2) and tris(l-pyrrolidinecarbo-dithioato)antimony(III). Hoskins et used the bidentate EtOCSj to prepare... 

Similar unfavorable constants can be obtained for the other cases. A successful agent in complexing the Hg(II) is BAL (British anti-Lewisite), 2,3-dimercaptopropanol, with potent sulfur ligands for the mercury, and also for arsenic, antimony, bismuth, and gold. It is injected intramuscularly in 10% solution in peanut oil at a dose rate of 3 mg/kg of body weight every 4 hr for two days, and after that at decreasing frequency until recovery. 

In the case of ligands with larger bite, i.e. chains between the sulfur atoms, cyclic disulfides may result, for example 5-chloro-l-oxa-4,6-dithia-5-stibocene,127 the structure of which consists of antimony in a distorted trigonal bipyramid with Cl and O in axial positions (39). A range of crystallographic data is contained in Table 18. 

A number of compounds of the p-block elements containing two bidentate ligands can be considered to be five-coordinate and trigonal bipyramidal if a non-bonding pair of electrons occupies one of the equatorial sites, for example [Sn(S2CNR2)2(lone pair)] and [Pb(RCOCH-COR)2(lone pair)].4 The greater repulsion observed from this line pair implies R(lone pair/bidentate) values of 0.6 for sulfur(IV) compounds, decreasing to 0.4 for selenium(IV) and 0.2 for tellurium(IV), antimony(III), tin(II) and lead(II).4... 

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