Bidentate ligands dithiocarbamate complexes

Among complexes of bidentate ligands, the dithiocarbamate Ir[S2CN(CH2)4]3 has octahedrally coordinated iridium (Ir-S 2.38 A) [153],... 

Various bidentate ligands like dithiocarbamate afford monomeric square planar complexes specific examples are Pt(S2CNEt2)2 and Pt(Se2CNBu)2 (confirmed by X-ray). A similar structure is found for the dithiobenzoate Pd(S2CPh)2 one form of the dithioacetate is dimeric, a second form is a mixture of monomers and dimers. 

Dithiocarbamate complexes of gold and their derivatives have been increasingly studied in recent years, being prepared with both gold(I) and gold(III). Complexes have been made featuring both monodentate and bidentate dithiocarbamate ligands. 

Another important class of bidentate ligands in gold chemistry are those composed of sulfur donor ligands such as dithiocarbamates, dithiolates, dithiocarboxylates, dithiophosphinates, dithiophosphates, and so on. The complexes prepared with these ligands are generally of the type Au2(p.-SS)(PR3)2]"+ or Au2(p-SS)(p-PP)] [153-155], [Au2(p-SS)2f [156, 157] or Au3( i-SS)2(PPh3)2 [158]. All these... 

Eight-coordinate dodecahedral complexes of the general type W(L-L)4 are known for several bidentate ligands such as dithiocarbamate, 8-quinolinol, substituted quinolinols, picoline and substituted picolines. 

The reaction of [W(CO)4(diphos)] with NOPF6 gives [W(CO)3(NO)(diphos)]PF6.398 It reacts with halides and dithiocarbamates to yield [W(CO)2(NO)(diphos)X] (X = Cl, Br, I) and [W(CO)(NO)(diphos)(S2CNR2] (R = Me, Et). Spectroscopic data suggest that in the last compound the CO and NO ligands are cis to one another. Similar complexes can also be obtained with other bidentate ligands.398... 

The structure of the Au(Et2Dtc)3 complex, originally reported by Akerstrom (7), has been determined (487). One of the dithiocarbamate groups in this molecule functions as a bidentate ligand, while the other two function as monodentate ligands. The coordination of the Au(III) ion is square planar (Table X). 

Values of the normalized bite b and the twist angle 8 for these complexes are given in Table 14. In sharp contrast to other tris(chelate) complexes, it is very clear that 8 is not a simple function of b. In all cases 8 is lower than predicted, and in many cases the trigonal prism with 8 = 0° is observed. These dithiolate ligands are clearly different from other bidentate ligands, even other sulfur donors such as MeSCH=CHS, dithioacetylacetonate, dithiooxalate, dithiophosphates, dithiocarbamates and xanthates. 

The influence the size of the chelate ring has upon the stereochemistry around the metal atom is clearly shown by complexes of the type [M(bidentate)4]. Bidentate ligands of small normahzed bite form dodecahedral structures, in which each of the BAAB trapezoids is formed from a pair of ligands (Fignre 13). There are nnmerous examples of this structure with three- and fonr-membered chelate rings snch as peroxide, nitrate, acetate, xanthate, and dithiocarbamate... 

The crystal structure of bis(NN-di-isobutyldithiocarbamato)nickel(ii). [Ni(S2-CNBu 2)2], shows that nickel is approximately square planar and co-ordinated by two symmetric bidentate ligands (Ni—S = 2.20 A) the ligand symmetry approximates to 2- The reduction mechanism of a series of nickel(ii) dithiocarbamates has been investigated in DMSO at the mercury electrode it is claimed to involve a dissociation to a nickel species which is more easily reduced than the nickel(ii) dithiocarbamate. An e.p.r. study of the reversible electrochemical reduction of nickel(ii) diethyldithio-carbamates in the presence of 2,2 -bipyridyl show that a bipy radical anion is formed initially. Ligand alkylation occurs when ao -dibromo-o-xylene is added to bis-(NiV-diethyldithiocarbamato)nickel(ii). The electron-transfer properties of 16 nickel(ii) dithiocarbamate complexes have been studied in acetone at a platinum electrode. Their oxidation is difficult and irreversible the overall process is ... 

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