Platinum, dithiocarbamate complexes

Palladium and platinum dithiocarbamate complexes are known for the - -2 and +A oxidation states, although the former is by far the more prevalent. Stable complexes are not known in either the +1 or +3 oxidation states, although some evidence has been found for the generation of both in electrochemical experiments (231,1561,1578). 

Considerably less is known about the chemistry of palladium and platinum 1,1-dithio complexes. Of late, there has been only one report that dealt with the synthesis of a large number of palladium dithiocar-bamates 392). Twenty-five yellow palladium dithiocarbamate complexes were obtained by reaction of PdCla with NaR2dtc in methanol solution. Several other reports have appeared in which a few dithiocarbamate complexes of palladium were synthesized. Thus, the novel [Pd (OH)2dtc 2], which is soluble in water, was isolated 393). The synthesis of optically active palladium(II) complexes of AT-alkyl-a-phen-ethyldithiocarbamates, similar to (XXIV), via the reaction between the optically active amine, CS2, and PdCl2, has been described. From ORD and CD spectra, it has been established that the vicinal contribution of a remote, asymmetric carbon center could give rise to optical activity of the d—d transitions of palladium 394). Carbon disulfide has been shown to insert into the Pt-F bond of [PtF(PPh3)3]HF2, and X-ray studies indicated the structure (XXIX). 

Unsymmetrically substituted dithiocarbamate complexes of platinum(II) can also be synthesized. Using NMR techniques, the barrier to rotation about the C=N bond is found to be in the region of 85 kJ mol-1. 809... 

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 ... 

Temperature-dependent luminescence spectra for a series of palla-dium(ii) and platinum(ii) complexes with thiocyanate, halide, and dithiocarbamate ligands have been investigated. The results show that the luminescence band maxima of palladium(ii) and platinum(ii) complexes have opposite shifts with increasing temperature. The palladium complexes exhibit a negative shift of at least 1 cm /K, while the platinum(ii) ones have a positive shift of -1-1.6 cm /K. ... 

Bevilacqua JM, Eisenberg R (1994) Synthesis and characterization of luminescent square-planar platinum(II) complexes containing dithiolate or dithiocarbamate ligands. Inorg Chem... 

Inorganic Derivatives.- 1,6-Anhydro 2-chloro-2,4-dideoxy-4-(diphenylphosphoryl)-P-D-glucopyranose, the P-in-the-ring sugar analogues (27) and (28)," the natural arsenic-containing riboside (29), methyl 4,6-0-benzylidene-3-deoxy-3-C-triphenylstannyl-a-D-altropyranoside, two isomeric chromium(III) complexes with 1,3,5-triamino-1,3,5-trideoxy-cw-inositol in the one structure, the vanadium(in) complex (30),and the platinum(Il)-dithiocarbamate complex (31). ... 

It is not clear when dithiocarbamates were first prepared, but certainly they have been known for at least 150 years, since as early as 1850 Debus reported the synthesis of dithiocarbamic acids (1). The first synthesis of a transition metal dithiocarbamate complex is also unclear, however, in a seminal paper in 1907, Delepine (2) reported on the synthesis of a range of aliphatic dithiocarbamates and also the salts of di-iTo-butyldithiocarbamate with transition metals including chromium, molybdenum, iron, manganese, cobalt, nickel, copper, zinc, platinum, cadmium, mercury, silver, and gold. He also noted that while dithiocarbamate salts of the alkali and alkali earth elements were water soluble, those of the transition metals and also the p-block metals and lanthanides were precipitated from water, to give salts soluble in ether and chloroform, and even in some cases, in benzene and carbon disulfide. 

A number of synthetic approaches involve the cleavage of a sulfur-element bond in order to generate the dithiocarbamate. Faraglia and co-workers (206, 207) developed a route to certain palladium and platinum dithiocarbamate from the thermolysis of dithiocarbamic ester complexes, upon loss of methyl halide (Eq. 27). 

Few reactions of bis(dithiocarbamate) complexes have been reported, aside from those with other metal salts that are described later. The platinum... 

Monodentate phosphine complexes have also been reported. Dithiocarbimato complexes [M(PR3)2(S2CNR)] of palladium and platinum have been prepared from [MCl2(PR3)2], primary amines, and carbon disulfide and can be reversibly protonated to give dithiocarbamate complexes [M(PR3)2(S2CNHR)] (Eq. 155) (1520). 

Zinc dithiocarbamates have been used for many years as antioxidants/antiabrasives in motor oils and as vulcanization accelerators in rubber. The crystal structure of bis[A, A-di- -propyldithio-carbamato]zinc shows identical coordination of the two zinc atoms by five sulfur donors in a trigonal-bipyramidal environment with a zinc-zinc distance of 3.786 A.5 5 The electrochemistry of a range of dialkylthiocarbamate zinc complexes was studied at platinum and mercury electrodes. An exchange reaction was observed with mercury of the electrode.556 Different structural types have been identified by variation of the nitrogen donor in the pyridine and N,N,N, N -tetra-methylenediamine adducts of bis[7V,7V-di- .vo-propyldithiocarbamato]zinc. The pyridine shows a 1 1 complex and the TMEDA gives an unusual bridging coordination mode.557 The anionic complexes of zinc tris( V, V-dialkyldithiocarbamates) can be synthesized and have been spectroscopically characterized.558... 

Pt(S2CNMe(Hex))2] and [Pd(S2CNMe(Hex))2] have been synthesized and used as precursors to grow the first TOPO-capped PtS and PdS nanoparticles and thin films of PtS and PdS by the metallo-organic chemical vapor deposition (MOCVD) method [204]. Platinum and palladium chalcogenides find applications in catalysis [205-210] and materials science [211,212]. The synthesis of thiocarbamato complexes of platinum and palladium from reaction of an aqueous solution of ammonium dithiocarbamate with the platinum or palladium salt has been reported by Nakamoto et al. [213]. However... 

Phosphorus is present in zinc dialkyldithiophosphate and deactivate platinum catalysts in engine exhaust systems. Using zinc, antimony and oxothiomolybdate dialkyl-dithiocarbamate (MoDTC) complexes alone or in combination with other lubricating oil additives appears to solve this problem. Antimony complexes are used also as extreme pressure agents while molybdenum ones as friction modifier additives (Hill et al., 1994). Analyses of Zn(dtc)2 decomposition using the thermogravimetric method, flash vacuum pyrolysis, and four-ball machine... 

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