Sulfur dithiophosphate complexes

Antimony has a great affinity for charged sulfur ligands which include thiolates, xanthates (R0CS2 ), dithiocarbamates (R2NCS2 ), and dithiophosphates ((RO)2PS2 ). In contrast to arsenic, where this chemistry is limited to oxidation state III, antimony forms compounds in oxidation states III and V. The xanthate, dithiocarbamate, and dithiophosphate complexes are mostly made by reaction of antimony(III) halides or organohalides with Na, NH4, or Ag salts of the acids. Complexes... 

Quite a few structural determinations have been made on dialkyl dithiophosphate complexes they have been recently reviewed by Haiduc." In the square-planar complexes [Ni (RO)2PS2 2] (R = Me, Et, Pr ) the coordination is symmetrical (isobidentate) with virtually equivalent P—S distances at 1.95-1.98 A and the Ni—S bonds are also identical at 2.21-2.22 A. In the trans octahedral complex [Ni (EtO)2PS2 2(py)2] the Ni—S distance is much longer (2.49 A). In the cis octahedral complexes [Ni((RQ)2PS2 2(phen)] (R = Me, Et) and [Ni (MeO)2PS2 2(bipy)] the Ni—S bonds trans to the sulfur atoms are some 0.04 A longer than those trans to the nitrogen atoms. 

Recently Zn NMR studies of imidazole and carboxylate complexes and the thermolysin-zinc complex have been described and Cd NMR studies of a wide range of complexes have been reported CdNMR data for pyridine adducts of Cd /3-diketonates show the influence of the sulfur and nitrogen donors on the chemical shift Cadmium NMR studies on cadmium fluoride have also been reported. A CdNMR study of Cd-enriched phosphine oxide complexes has been reported " and a multinuclear NMR investigation and Cd) of cadmium dithiophosphate complexes has been described. ... 

More recendy, molecular molybdenum-sulfur complexes and clusters have been used as soluble precursors for M0S2 in the formulation of lubricating oils for a variety of appHcations (70). Presumably, the oil-soluble molybdenum—sulfur-containing precursors decompose under shear, pressure, or temperature stress at the wear surface to give beneficial coatings. In several cases it has been shown that the soluble precursors are trifunctional in that they not only display antifriction properties, but have antiwear and antioxidant characteristics as weU. In most cases, the ligands for the Mo are of the 1,1-dithiolate type, including dithiocarbamates, dithiophosphates, and xanthates (55,71). 

Metal complexes of ligands containing a sulfur donor in conjunction with nitrogen, oxygen or a second sulfur have been reviewed in the past [11-13]. For example, reviews of the coordination compounds of dithiophosphates [14], dithiocarbamates [15, 16], dithiolates [17], dithiodiketonates [18], and xanthates [16] have appeared. The analytical aspects [19] and the spectral and structural information of transition metal complexes of thiosemicarbazones [20, 21] have been reviewed previously. Recent developments in the structural nature of metal complexes of 2-heterocyclic thiosemicarbazones and S-alkyldithiocarbazates, depicted below, are correlated to their biological activities. 

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... 

Homoleptic gold(III) derivatives with dithiolate, ligands of the type [Au(S-S)2] are well known and are usually prepared from [AuC14] with the dithiol some examples are with 1,2-benzene dithiolate, maleonitriledithiolate, dmit, and so on, [164, 336]. Similar complexes have been reported for bidentate sulfur ligands such as dithiocarbamates, dithiophosphates, and so on, [41]. Other derivatives as the trinuclear species [Au(C6F5)(S2C6H4)]3 [337] or the complex with one nido and one closo-carborane dithiolate are known [338]. Figure 1.72 collects some of these complexes. 

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. 

Table 5.15. Protective tribofilm formation from degradation of molybdenum dithiocarbamate (MoDTC), molybdenum dithiophosphate (MoDDP) and molybdenum amine-ester complex (MoAC) directly and in combination with ZDDPs or sulfur compounds...

As relatively hard acids, Ln + ions would not be expected to complex readily with soft donor atoms like sulfur. Apart from the thiolates discussed in (see Section Polypyrazolylbo-rates ), several types of complex with chelating ligands such as dithiophosphates and dithiocarbamates have been synthesized by reaction in nonpolar solvents. These fall into two main classes, Ln(S2Q)3 and [Ln(S2Q)4] (Q = R2NC (dithiocar-bamate) or R2P (dithiophosphate)). Several crystal structures... 

In Comprehensive Coordination Chemistry (CCC, 1987), practically all known types of sulfur-containing ligands, e.g., dithiocarbamates, dithiocarbonates (xanthates), dithiocarboxylates, dithiophosphates, and related ligands1,2 were well covered. Here only the most popular sulfur-containing ligands will be treated, i.e., those which continued to be used frequently in coordination chemistry, with emphasis on new results. The 1,1-dithiolato ligands and their complexes have been reviewed rather comprehensively in other earlier publications,3-5 which are still useful sources of information about older literature. In this section, those ligands that have not... 

When sulfur replaces oxygen, chelating begins to dominate over bridging, as it occurs in complexes with ligands derived from dithiophosphate derivatives and dithiocarbamates. ... 

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