Tellurium , dithiocarbamate complexes

The structural chemistry of some metal dithiocarbamates, i.e. systematics, coordination modes, crystal packing, and supramolecular self-assembly patterns of nickel, zinc, cadmium, mercury, organotin, and tellurium, complexes has been thoroughly analyzed and discussed in detail. Supramolecular self-assembly frequently occurs in non-transition heavier soft metal dithiocarbamates. Thus, lead(II), bismuth(III) zinc, cadmium, and (organo)mercury dithiocarbamates are associated through M- S secondary bonds, to form either dimeric supermolecules or chain-like supramolecular arrays. The arsenic(III) and antimony(III) dithiocarbamates are... 

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Simultaneous speciation of inorganic selenium and tellurium in water samples by ICP-MS was performed after selective solid phase extraction (SPE), as discussed by Yu et al 9 Under acidic conditions Se (IV) and (TV) complexes with ammonium pyrrolidine dithiocarbamate were formed. The detection limits for Se and species in water samples were found to be 7ngl 1 and 3 ng 1 1, respectively. 

The complex, tetrakis[thiourea]tellurium dichloride, reacted with bis[2-hydroxyethyl]di-thiocarbamic acid in aqueous methanol to precipitate tellurium bis[his(2-hydroxyethyl)dithiocarbamate] as an orange solid". 

There are no oxygen dithiocarbamate complexes and, although dithiocarba-mates do bond to sulfur, forming thiurams, these are considered as a separate class of compound and fall outside the scope of this chapter. While the dithiocarbamate complexes of selenium remain relatively few in number, those of tellurium have been studied more extensively, with particular attention being paid to the different possible coordination numbers and geometries displayed by the metal atom. 

Homoleptic dithiocarbamate complexes of both teUurium(II) (215, 293, 294, 296, 302-311) and tellurium(lV) (293, 294, 296, 302, 304-306, 309, 310, 312-315) are well known. The molecular structures of the bis(dithiocarbamate)tel-lurium(II) compounds, [Te(S2CNR2)2], are analogous to those of the corresponding Se compounds The Te atom exhibits a planar trapezoidal coordination geometry, with the two dithiocarbamate ligands bound in an anisobidentate fashion [Te—S(ave) = 2.52 (short) and 2.83 A (long)]. Tellurium(II) has a tendency for pentacoordination and, with the exception of [Te(S2CNCy2)2], which is monomeric (311), there is a short intermolecular Te-- S contact (av... 

Dithiocarbamate ligands do not appear to complex tellurium(VI) and have been used successfully to separate aqueous mixtures of Te(IV) and Te(VI)... 

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