Dithiooxalates

Considering the four thiooxalates 1,1-dithiooxalate (i-dto), 1,2-dithiooxalate (dto), trithiooxalate (trto), and tetrathiooxalate (tto), dto is by far the most prominent in Ni11 coordination chemistry.976... 

A different, indeed unique, type of spin cross-over behavior is claimed for the mixed valence dithiooxalate salt Pr 4N[Fe Fe (dto)3]. Here the spin change is associated with electron transfer, with the bridging dithiooxalate favoring Fe —S bonding at higher temperatures, Fe —O bonding at lower temperatures ... 

The nickel chelate with dithiooxalate anion (S Oi-, dto) is much more stable than that with the oxygen analogue. K2Ni(dto)2 has been obtained in two polymorphic forms. A dark-red... 

Spectral data used to characterize these structural types are given in Table 45. The type of isomer obtained for the dithiooxalates depended on the kinetic inertness of the original complex and occasionally the resulting products were not the energetically most stable species. 

In such cases slow rearrangements to the thermodynamically favoured form occurred. With kinetically labile complexes, the bridging mode adopted by the dithiooxalate ligand was a reflection of the thermodynamic stability of M—S2C2O2 vs. (R3P)2—Ag—S2C2O2 interactions. 

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 potassium salt of monothiooxalate can be prepared.46 Two isomers of the dithiooxalic dianion (1,1 and 1,2) and the trithiooxalato anion can also be prepared.46 Transition metal complexes of these ligands are unknown until now. The tetrathiooxalato anion was synthesized and characterized in in the form of the nickel complex. The ligand coordinates as a 1,2-dithiolate.47... 

A detailed study of the electronic spectra of the d8 complexes [M(dto)2]2 (M = Ni, Pd, Pt) and [Au(dto)2] has been reported. The spectra are virtually identical in a variety of solvents, indicating that axial perturbations due to the solvent are minimal. Dithiooxalate has a high position among square-planar NiS4 chromophores in the spectrochemical series for dithio ligands the series is maleonitriledithiolate < (CF3)2C2S2 < diethyl dithiophosphate < ethyl xanthate < diethyl dithio-carbamate < 2,3-dimercaptopropanol anion < dithiomalonate dithiooxalate.145... 

Photochemistry of Oxalate and Dithiooxalate Complexes of Nickel, Palladium, and Platinum... 

Another interesting structural variation has recently been reported298 as occurring in some mixed metal compounds of dithiooxalate, i.e. MMn(S2C202)2,7.5 H20 (for M = Ni and Cu). These have the linear polymer structure (112), with seven-coordinate Mn11. 

Bifurcated hydrogen bonds between dipyridinium cations and coordinated dithiooxalates have been used to assemble tapes [130] with similar geometry to those in which coordinated halides act as acceptors [15]. Replacement of dipyridinium with 4-carboxypiperidinium gave a structure in which the anions are linked by carboxylic acid dimer assembled dications. Similar bifurcated hydrogen bonds were observed in the structures of bipyridinium salts of anilic acids [131]. 

---