Platinum-bound phosphine

Platinum-bound phosphine and rhenium-ligated carbonyl irreversibly exchange on w arming a solution of Re2Pt(/r-H)2(CO)j (PPh3)2l above 213 a mix-... 

Although the oxidation of tertiary phosphines by these catalytic processes has minimal useful application, it needs to be considered as a problematic side reaction in homogeneous catalysis. Much effort is being currently expended to immobilize platinum metal phosphine complexes on heterogenized tertiary phosphine supports, and irreversible oxidation at phosphorus on these supports effectively destroys the supported catalyst. Recent observations that the compound Rh6(CO)i6 catalyzes the oxidation of tertiary phosphines correlate with the report that phosphine oxidation occurs with molecular oxygen on Rh6(CO)i6 bound to diphenylphosphino-functionalized poly(styrenedivinylbenzene). Thus, in order to use these phosphinated polymer-supported rhodium catalysts, one needs either to rigorously exclude oxygen, or to find a way to inhibit the simultaneous catalyzed phosphine oxidation. 

Chiral bis-phosphine acylplatinum complex 210 with a strong acid such as TfOH serves as an effective enantio-selective catalyst for aldol-type reactions of aldehydes with ketene silyl acetals (Equation (127)).486 The presence of water and oxygen in the catalyst preparation step is required to obtain the highly enantioselective catalyst. The intermediacy of a C-bound platinum enolate was suggested by IR and 31P NMR spectroscopies. 

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)]. 

Reduction by Hydrazine. This was a very successful method for preparing the palladium (0) and platinum (0) derivatives with tertiary phosphines, phosphites, and arsines (4, 129, 130, 133). Also, the tetra-isocyanidenickel(O) compounds can be obtained at high yield in this way (132). In the case of platinum this reduction can give place either to zero valent derivatives (130) or to platinum (II) hydrides (49), according to the reaction conditions, the nature of the ligands, and the halogen atoms bound to the metal. This reduction is a very complicated reaction (186) in any case. 

Polyamides were successfully used as supports. Polyamides 14 and 15 were allowed to react with H2PtCl6, PtCl2(CH3CN)2, and [RhCl(CO)2]2 to give the corresponding immobilized catalysts. The IR study shows that the carbonyl oxygens of amides are the sites of coordination to platinum and rhodium. It was found that the activity of those immobilized catalysts correlates with the crystallinity of the polyamides, viz., the higher the crystallinity, the lower is the catalytic activity. Partial phosphination of 15 did not show any effects on catalytic activity. The polyamide-bound catalysts are thermally stable and reusable . 

In the yS-CyD complex with platinum phosphine [220], the trimethylphosphine ligand is bound at the primary hydroxyl side of the fi-CyD cavity. On the other hand, alkyl ligands, i-butyl, -butyl, -hexyl, and cyclohexyl groups of alkyl(aqua)-cobaloximes are inserted into the cavity from the secondary hydroxyl side [221-224]. The channel cavity formed by fi-CyD dimers includes diaqua(benzoate)-hydroxydioxouranium(VI). Two benzoate moieties are inserted into the dimer cavity and the U(VI) atom is located at the primary hydroxyl side without direct contact with the host molecule [225]. 

Carbonylation of [Pt(Cl)(Me)](n-Cl)(p-Ph2PPy-K-P.A0[Pt(Cl)(Me)(DMSO)l is site selective, only the methyl group on the phosphine bound platinum centre is converted to an acyl group. A slower reaction eventually leads to the unusual salt [Pt(Cl)(Me)](p-Hi2H y- f-P> (p-l%2PPy-K-JV,P)pPt(COMe)] [Pt(CO)(Cl)2(COMe)] which was structurally characterised. ... 

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