Platinum triphenylphosphine complexes

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. 

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. 

Platinum(II) halides react with cyanate salts to give cyanato complexes. Reacting the compounds Pt(NCO)4 with triphenylphosphine gives Pt(NCO)2(PPh3)2.1628 These platinum(II) complexes are N-bonded. Treatment with carbon monoxide and alcohol yields the complex (172 equation 476).1629... 

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... 

Tertiary phosphine groups with long alkyl chains bound directly to phosphorus or substituted at the para position of triphenylphosphine give rise to a range of interesting and potentially useful complexes. In particular these may be used to prepare polyolefin hydrogenation catalysts based on platinum(II) and palladium(II) complexes that are both more active and more selective towards reduction to monoolefins than previous catalysts based on these systems. The platinum(II) complexes are better than the palladium(II) complexes. Additionally the new phosphines are more effective than triphenylphosphine in promoting the oxidative addition of methyl iodide to trans- [Rh(PR3)2Cl(CO)]. 

The bis(triphenylphosphine)platinum(0) complex of cyclopentyne (240) [Eq. (32)] is the only complex of a five-membered cycloalkyne that is discussed in an earlier review.2 The mechanism of its preparation is significant because 239 was isolated and shown to react with Na/Hg to give 240, thus suggesting that 7r-complexes may play a role in the formation of dw complexes of larger cycloalkynes2 36 82 and, possibly, cyclic allenes (Section IV)82 where trapping of the free intermediate had often been presumed. 

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. ... 

Carbonatobis(triphenylphosphine)platinum(II) is useful for the preparation of dianionobis(triphenylphosphine)platinum(II) complexes as well as olefin, acetylene and carbonyl derivatives of platinum(0). The method can be used to prepare Pt[P(C6Hs)2CH3] jCCOa) and Pt[As(C6Hs)3] 2(C03). A procedure is available for the preparation of ds-[diacetatobis(diphenylphosphino)pla-tinum] (ds-[Pt(CH3C02)2[P(C6Hs)2l 2]). 

Clark and his co-workers have shown that water will provide a convenient source of the hydro ligand in reactions with cationic platinum(II) complexes (Eq. 40). Reaction occurs when L is triethylphosphine or triphenylphosphine 93, 81), when X is a halogen, and also when L is an alkylarsine 80). The mechanism has been studied and is considered to proceed via an intermediate carboxylate 95, 96). 

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 ... 

An associative mechanism for carbonylation of iodobis(triphenylphosphine)aryl-platinum(II) complexes has been suggested. The carbon monoxide insertion reaction of PtI(Me)(CO)(PPh3), promoted by tertiary arsines or by SbPha, involves the intermediacy of the three-coordinate intermediate PtI(COMe)(PPh3). The nature of the intermediates in the carbonylation of trans-PtX(PhXPR3)2 was investigated and found to involve formation of a five-coordinate complex ". ... 

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 . 

Platinum(0)-triphenylphosphine complexes also give a mixture of mono- and diadduct when employed as catalysts for the hydrosiiyiation of isoprene ... 

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