Ligand diethyldithiocarbamate

The mechanism proposed72 involves initial nucleophilic attack at the carbene carbon by the dithiocarbamate anion, effectively resulting in addition across the metal-carbon bond. Rearrangements of the dithiocarbamate ligands then form an V-allyldithiocarbamate species Complex 53 was isolated from the reaction mixture of 51 with the diethyldithiocarbamate and identified by X-ray crystallography. 

The first osmium(IV) thiolato complex, [Os(salen)(SPh)2] (132), was prepared by the reduction of [0s(0)2(salen)] with thiophenol in CH2Cl2. The complex has a distorted octahedral structure, and both phenyl groups tilt away from the methylene bridge of the salen ligand, which is in the gauche confirmation. The mean Os—S distance is 2.32 A, which is shorter than that (2.415 A) in [Os2(Et2dtc)6](PF6)2 (Et2dtc = A,A-diethyldithiocarbamate). 

In the a-modifications of silver(I) diethyldithiocarbamate irregular hexamers are linked in chains by weak bonds only (Ag—-S = 299pm). Two of the six silver atoms have four-fold coordination, the others three-fold. Two ligands coordinate to only two metal atoms, the others to four. Five short metal-metal distances occur in each of the hexamers.323 In the /3-modification, which is a true high polymer, all the silver atoms have four-fold coordination and all the ligands are linked to three metal atoms, (39). There are only two short metal-metal distances per six silver atoms. Crystals of the /3-form were obtained from CS2 solutions cooled to -40 °C. Ag—S bond lengths were in the range 251-274 pm.324... 

A number of metal ions may be separated by TLC as their diethyldithiocarbamate (DDTC) chelates and are detected by a ligand-exchange reaction between a metal-calcein complex and the DDTC chelate [198]. The limits of visual detection are 0.1-2 ng per spot for the metal ions. 

Fig. 8.5. Examples of complex formation by chelating ligands, showing (a) a four-membered ring with diethyldithiocarbamate (dtc), (b) formation of five-membered rings with ethylenediaminetetraacetate EDTA and (c) a six-membered ring with acetylacetonate (acac).

Of the complexes studied, those with ancillary ligands that contain sulfur atoms have received the most attention. Among the most studied are the bis(dial-kyldithiocarbamate) molybdenum oxido complexes [196,197], Unfortunately, although these complexes react with certain enzyme substrates, their common problem as models for Moco active sites involves the propensity of the Movl dioxo and MoIV monoxo complexes to form a comproportionated Mov p-oxido dimer (Eq. 13 dtc = diethyldithiocarbamate). 

Two crystalline modifications of mercury(n) NN-diethyldithiocarbamate have been reported.208 The a-form consists of dimeric Hg2(S2CNEt2)4 units, in which the metal atom is five-co-ordinate, in a manner similar to analogous zinc and cadmium complexes. The P-form is composed of essentially monomeric Hg(S2CNEt2)2 units, with the two ligand molecules co-ordinated in a plane through the S atoms (Hg—S = 2.40 A). 

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