Dithiophosphate complexes

Photoelectron spectroscopy of metal dithiocarbamate, xanthate and dithiophosphate complexes. 

Metal complexes of 1,1-dithiolates have been reviewed by Coucou-vanis (1) Eisenberg (2) presented a systematic, structural review of dithiolato chelates, and Stokolosa ct al. (3) reviewed dithiophosphate complexes in detail. Earlier reviews (4-3) covered less recent work in greater detail. Following initial work by Delepine (9), 1,1-dithiolato complexes were more intensively studied between 1930 and 1941 (10-16). There is, however, continuous interest in the synthesis, characterization, electronic structures, and bonding of these complexes. 

Analogous to the dithiophosphate complexes, cis octahedral complexes are formed with bident-ate ligands like phenanthroline, 2,2 -bipyridine, or tmeda and trans octahedral complexes are formed with monodentate ligands like pyridine and its derivatives. Some examples are mentioned with linear bidentate ligands like 4,4 -bipyridine, which build up ID chains by bridging the [NiL2] molecules.926-933... 

Iron(II)-5, 5 -dithiophosphate complexes tend to be unstable with respect to oxidation to iron (III), but 1,10-phenanthroline stabilizes iron(II) in the di-isopropyldithiophosphate complex [Fe S2P(OPr% 2(phen)].i ... 

Metal dithiophosphate complexes can be considered to be derivatives of the parent esters. Since World War II there has been wide-spread usage of dithiophosphate esters, e.g., 2-4, as pesticides and also related development of such compounds as war gases im.ios) Dithiophosphate esters inhibit the action of several ester-splitting enzymes in living organisms. 

Metal dithiophosphate complexes are involved in a wide variety of analytical methods for metals. Diethyldithiophosphoric acid reportedly 13-1 is) fonns complexes with thirty-five elements, mainly metals, in various oxidation states which are useful for solvent extraction. No attempt is made here to detail all the applications to solvent extraction methods which have been described since these ate summarized in the texts listed. Dithiophosphoric... 

Although cognizant of the applications, realized and potential, of metal dithiophosphate complexes, we only describe the preparation, properties and reactions of reasonably well-diaracterized compounds here. This is so in view of the availability and reliability of the literature reviewed, not from a desire to neglect the contributions to dithiophosphate chemistry available in the rather voluminous patent literature. 

The reasonably well-established dithiophosphate complexes are listed in Table 1. Complexes alleged to be involved in colorimetric analytical methods, solvent extraction and flotation procedures are generally omitted unless they have also been characterized in the solid state. 

The preparation of metal dithiophosphate complexes usually involves the reaction of metal halides or acetates with dithiophosphoric acids or their salts. The metal complexes are generally purified by repeated fractional crystallization from halocarbon solvents such as chloroform. The reactions of mixtures of alcohols and alcohols and phenols with phosphorus(V) sulfide allegedly,... 

Reactions of dithiophosphoric acids and their salts with complexes are also employed to prepare dithiophosphate complexes, e.g.,... 

Many dithiophosphate complexes have been found to be associated in solution. Zn(ethyl-dtp)2 is monomeric in chloroform solution but polymerized in the... 

Oxovanadium(IV) complexes with dithiophosphate ligands have been extensively examined <8,121.161,252,386) x typical ESR spectrum is shown in Fig. 7. In addition to the eight vanadium 1=112 hyperfine lines phosphorus (/ = 1/2) superhyperfine splitting is also observed. The phosphorus superhyper-fine splitting can be considered a bit unusual since the phosphorus is located about 3 A or more away from the metal ion. P and As superhyperfine splitting has been observed in the ESR spectra of ill-defined vanadium phosphine 388) and arsine 389) complexes but in those cases, presumably, direct V-P and V—As interactions occur. ESR parameters have been tabulated for a large number of dithiophosphate 121,252) dithiophosphinate 121.252) complexes. Evaluation 3i) of the fractional 3s character of unpaired electron in dithiophosphate complexes yielded a value of 1.35%. The vanadyl(IV) complexes possess approximate C2V symmetry. The unpaired d electron resides... 

The ESR spectra of copper(II) dithiophosphate complexes have been extensively studied 90,i2i,i6i,386,407-4is) Solutions and frozen solutions have been studied exhaustively whereas comparatively little single-crystal data is available 159,387) typical solution ESR spectrum is shown in Fig. 11. The high... 

Before concluding, it is worthwhile to note that photoelectron spectra 497) and X-ray K-absorption spectra 498) have not been reported for R-dtp complexes. The results of these techniques should be particularly useful for characterizing and probing the electronic structure of dithiophosphate complexes. 

The dithiophosphate complexes react with Ph3PO to give adducts, whose crystal structures... 

Certain classes of ligand deserve special mention as their Mo02+ complexes have received particular attention. The 1,1-dithiolate ligands, especially A,A-disubstituted dithiocarbamates, have been very thoroughly studied.131-133 Evidence for the existence of the dithiophosphate complex Mo02[S2P(OEt)2]2 in solution has been obtained.95 This and a number of other dithiolate complexes may be unstable toward internal redox in which the S ligand serves as the reductant to produce a lower valent Mo—S complex. 

The luminescent binuclear gold dithiophosphate complexes [Au2 S2P-(OR)2h] (R = Me, Et) were found to possess comparable intra- and intermolecular aurophilic contacts and afforded one-dimensional Au - Au chain structures [60]. At 77 K, solid samples of [Au2 S2P(OMe)2 2] displayed multiple emission bands, with the two concentration-dependent higher energy bands at 415 nm (r = 20 ns) and 456 nm (r = 2.16 is) assigned to XMC and 3MC emission, respectively, while the lower energy band at 560 nm was attributed to a LMCT excited state. [Au2 S2P(OR)2 2] was further shown to exhibit intense luminescence of different colors and striking thermochromism of the emission in frozen glasses of different solvents. 

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. ... 

Photoelectron spectroscopy of metal dithiocarbamate, xanthate and dithiophosphate complexes. J. O. Hill, R. J. Magee and J. Liesegang, Comments Inorg. Chem., 1985,5,1 (63). 

Table 4.4. Kinetic Data for the Reactions of Dithiophosphate Complexes of Pt, Pd, and Ni with N,N-Diethylthiocarbamate ...

The coordination mode of the dithiophosphate ligands and the overall geometry of the complex (shown in Fig. 2.4, bottom) match what is known in the literature. Several lanthanide dithiophosphate complexes are published in the Cambridge Structural Database (CSD) [36], and they fall in one of the three categories anionic complexes with four dithiophosphate ligands [37,38], neutral complexes with three dithiophosphate ligands and two neutral unidentate ligands [39—43], and cationic... 

The presence of coordinated chloride ions, however, is unprecedented. Most lanthanide dithiophosphate complexes are synthesized from lanthanide chloride hydrates using methods derived from one published by Pinkerton et al. [45]. In... 

It is also quite common for cationic and anionic complexes of the same metal ion to crystallize as a salt. This happens especially often for metals that form stable polyatomic ions, such as tetrachlorocobaltate [65,66] or tetrachlorozincate [67,68]. Rare earths readily form both cationic and anionic complexes, and the CSD contains many examples of crystal structures showing this phenomenon in the rare earths such as the published dithiophosphate complexes discussed previously [33]. In this case the two metal ions are bridged only through outer-sphere interactions but are inseparable (without changing the speciation) since their complexes act as counterimis to each other. It would seem reasonable that charged complexes containing two different metal ions could form a salt as well, but this approach is not as well documented. This is probably because it is difficult to control whether or not the two metals separate on crystallization if there is no covalent linkage between them. 

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