Triphenylphosphine complexes with platinum

It has recently been shown (38a) that the triphenylphosphine complexes of platinum are in all probability complex hydrides of platinum(II), with general formula [(Ph3P)jPtTI2] where x - 2, 3, or 4. As these materials have always been used in the preparation of other platinum(O) complexes, it is now doubtful whether such complexes have in fact ever been obtained since it is possible that they are all hydrides. 

Non-ionic thiourea derivatives have been used as ligands for metal complexes [63,64] as well as anionic thioureas and, in both cases, coordination in metal clusters has also been described [65,66]. Examples of mononuclear complexes of simple alkyl- or aryl-substituted thiourea monoanions, containing N,S-chelating ligands (Scheme 11), have been reported for rhodium(III) [67,68], iridium and many other transition metals, such as chromium(III), technetium(III), rhenium(V), aluminium, ruthenium, osmium, platinum [69] and palladium [70]. Many complexes with N,S-chelating monothioureas were prepared with two triphenylphosphines as substituents. 

The triphenylphosphine complex 42 b reacts with bromine to give a platinum(IV) species 42f, assigned the cyclic structure with four platinum-carbon c-bonds. The reaction sequence here must begin with the attack of a bromine molecule on an uncoordinated olefin, as otherwise it is hard to see why two metal-carbon bonds are formed, and not one metal-carbon and one metal-bromine. 

Except for 1-ethynylcyclohexanol, it appears that the addition of protonic acid to triphenylphosphine platinum hydrides is unfavorable. Nevertheless, the existence of such complexes with triethylphosphine ligands is proved sufficiently since, in addition to the isolation of complexes with hydrochloric acid (10, 14), good evidence is presented for the intermediacy of triethylphosphine Pt(IV) hydrides with silanes and phosphines (15,16). 

The zerovalent compound Pt(C2H4)(PPh3)2 reacts with C(PPh3)2 to give the platinum(0) ylide complex where partial triphenylphosphine transfer to platinum has occurred (equation 144).426... 

These reactions can be used to prepare a novel series of complexes where cyclic alkynes can be stabilized by coordination to platinum(O).831,832 The compounds are feasible because coordination of a triple bond to platinum causes a distortion of the alkyne from linearity by displacement of the alkynic substituents back away from the platinum. Also these methods can be used to prepare platinum(O) alkyne complexes with substituents other than triphenylphosphine.833-836... 

Tertiary phosphite complexes of platinum(O) can be prepared by the hydrazine reduction of PtCl2 P(OR)3 2 (equation 384), or by replacement of triphenylphosphine in Pt(PPh3)3 (equation 385).1233 Alternatively the complexes can be prepared from Pt(j73-C3H5)(r/5-Cp) and the phosphite.1268 Heteronuclear INDOR measurements show that 2/(PP) has a value of +81 Hz in Pt P(OMe)3 4. A detailed synthesis of Pt P(OEt)3 4 has been published from K2PtCl4 and triethyl phosphite with KOH (equation 386).1267 The product is obtained as colorless crystals which can be handled in air. 

The carbon diselenide and carbon sulfide selenide complexes of platinum(0) can be synthesized from Pt(PPh3)3. Reaction of the compounds with chelating phosphines results in substitution of the triphenylphosphines (equation 541).1866 With COS the C,S-bonded compound Pt(COS)(PPh3)2 is formed from Pt(PPh3)3. The reaction can also be used to prepare the dithiocarbonato complex Pt(S2CO)(PPh3)2.1867... 

Pinacolone, o-(diphenylphosphino)benzoyl-coordination chemistry, 401 Piperidine, IV-hydroxy-metal complexes, 797 pA a values azole ligands, 77 Plant roots amino acids, 962 carboxylic acids, 962 Plastocyanin copper binding site, 557 copper(II) complexes, 772 copper(II) site in, 770 Platinum, dichlorobis(benzonitrile)-IR spectrum, 264 Platinum, cis-dichlorodianunine-antitumor activity, 34, 979 Platinum, ethylenebis(triphenylphosphine)-reactions with 5,6-dimethyl-2,l,3-benzothiadiazole, 194 Platinum blue formation, 265 Platinum complexes acetylacetone reactions, 380 amides, 491 amidines... 

In studies of the reactions of organotin compounds with platinum(O) and platinum(II) complexes, we have obtained a series of cis-bis(triphenylphosphine)platinum(II) complexes in which one... 

The formation of complexes of l,2,3,4-thiatriazole-5-thiol has been well described in CHEC-II(1996) 1,2,3,4-thiatriazole-5-thiol can form complexes with various metals such as palladium, nickel, platinum, cobalt, zinc, etc. <1996CHEC-II(4)691>. These complexes can be prepared either by cycloaddition reactions of carbon disulfide with metal complexes of azide anion (Equation 20) or directly from the sodium salt of l,2,3,4-thiatriazole-5-thiol with metal salts. For instance, the palladium-thiatriazole complex 179 can be obtained as shown in Equation (20) or it may be formed from palladium(ll) nitrate, triphenylphosphine, and sodium thiatriazolate-5-thiolate. It should be noted that complexes of azide ion react with carbon disulfide much faster than sodium azide itself. 

In addition to the complexes of platinum(II), a number of olefin complexes of platinum(O) have been prepared. Chatt, Shaw, and Williams (103) have described the complex (olefin)bis(triphenylphosphine)-platinum(O) prepared by reaction of the olefin at 60°C with cis-dichloro-bis(triphenylphosphine)platinum(Il) in ethyl alcohol containing hydrazine hydrate. The complex was formed only with ethylene complex (C2H4)Pt[P(CgH5)3]2 has been prepared (121) by reduction of the corresponding oxygen complex with sodium borohydride in the presence of the olefin. 

An iron tetracarbonyl complex (295) ° and a platinum bis(triphenylphosphine) complex of thiete 1,1-dioxide have been prepared. Platinum complexes of 3-phenyl- and 3-(p-bromophenyl) thiete 1,1-dioxide also have been prepared. No complex was obtained with the 3-t-butyl derivative. The pale-yellow, crystalline iron complex decomposes in refluxing hexane in the presence of excess sulfone to Fe2S2(CO)9, indicating a drastic structural rearrangement. Other carbon-containing fragments were not observed. The bis(triphenylarsine)platinum complex of 3-02-bromophenyl) thiete sulfone is decomposed photochemically to the thiete sulfone. The same result is achieved on treatment of the complex with tetra-cyanoethylene. ... 

A general approach to alkenylplatinum(II) complexes involves the use of alkenyl triflates. Reaction of [Pt(PPh3)4] produces an alkenyltris(triphenylphosphine)-platinum(II) cation, whereas with [Pt(PPh3)2(C2H4)] a complex with coordinated triflate is obtained ... 

Consistent with low stability for compounds of this type, loss of carbon monoxide has been observed when metal complexes containing two adjacent carbonyl functions have been prepared by an indirect route. For example, a-ketohydrocarbyl complexes of palladium(II) or platinum(II) have been prepared by oxidative addition of the appropriate organic halide to palladium(O) or platinum(O) triphenylphosphine complexes ... 

Pd and Rh affect the determination of Pt. The smaller effect of other platinum group elements is due to the lower rate of formation of their complexes with SnCl.. A convenient method of separating Pt from Pd consists in extraction of Pt with triphenylphosphine oxide solution in 1,2-dichloroethane [7] (see the procedure below). 

An aromatic nitro function hydrogenates to the corresponding amine in high yield over palladium-on-carbon in a process that is slightly superior to that using platinum. Homogeneous reduction of aromatic compounds (1) by a triphenylphosphine complex of palladium yields anilines 2 along with minor quantities of azobenzene and azoxyben-zene derivatives . 

In addition to pyridinium based catalysts and cyclodextrin derivatives, some special compounds have also been reported to be useful inverse PT catalysts for specific reactions. Te-tramethyl ammonium salts that are ineffective as PT catalysts due to their high solubility in the aqueous phase have been found to be effective inverse PT catalysts in some systems. Some metal compounds like platinum, palladium, and rhodium can strongly complex with water-soluble ligands such as the trisodium salt of triphenylphosphine trisulfonic acid, and act as effective inverse PT catalysts. These complexes are soluble in the aqueous phase only and, thus are easily recov-... 

Such aquo complexes react with triphenylphosphine yielding the corresponding phosphino compound. It is noteworthy that while the dinuclear platinum complexes do not react with water to produce the hydroxo compound and the formation of this hydroxo compound requires the refluxing of the halide complexes with KOH or NBU4OH for 24 hours, the silver derivatives decompose in solution with NBU4OH and react with water under mild conditions to form the hydroxo complex. Similarly, while the dinuclear platinum complexes do not react, for instance, with tht to cleave the bridging Pt(y(i-X)Pt system, the aquo silver compound reacts with tetrahy-... 

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