Platinum alkyls and aryls

Table 3.11 Bond lengths (A) in palladium and platinum alkyls and aryls M(PR3)2R X...

Substantially more work has been done on reactions of square-planar nickel, palladium, and platinum alkyl and aryl complexes with isocyanides. A communication by Otsuka et al. (108) described the initial work in this area. These workers carried out oxidative addition reactions with Ni(CNBu )4 and with [Pd(CNBu )2] (. In a reaction of the latter compound with methyl iodide the complex, Pd(CNBu )2(CH3)I, stable as a solid but unstable in solution, was obtained. This complex when dissolved in toluene proceeds through an intermediate believed to be dimeric, which then reacts with an additional ligand L (CNBu or PPh3) to give PdL(CNBu )- C(CH3)=NBu I [Eq. (7)]. 

Isocyanides.—The proposed mechanism for insertion of isocyanides into platinum-alkyl and -aryl bonds, as in (20), is shown in Scheme 3. The... 

All the platinum alkyl and aryl complexes so far discussed have been platinum(II) derivatives. Remarkably, some of these complexes undergo... 

Platinum in particular forms numbers of stable er-bonded alkyls and aryls in both the +2 and +4 states. 

Palladium and platinum form a wide range of very stable alkyls and aryls in the (+2) state (section 3.8.4) generally with supporting ligands like tertiary phosphines [85, 189],... 

Insertion reactions of platinum(II) alkyl and aryl complexes (144, 153, 171), nucleophilic displacement of isocyanide from [Pt(PRj)2(CNCH3)2] (147) and additions of alcohols and related substances to isocyanides bonded to platinum (8, 9, 25, 33, 34, 100, 117) were discussed earlier. 

The cis/trans isomerization of platinum(II) complexes is a subject which will be discussed in some detail when the halide (Group VII) complexes are covered. Nevertheless the importance of reductive elimination reactions of platinum(II) alkyl and aryl complexes makes it imperative that this reaction be discussed here for alkyl and aryl platinum(II) compounds. 

S-bonded alkyl and aryl sulfinato complexes can be prepared by the reaction of sulfonyl chlorides with Pt(C2H4)(PPh3)2,1633 the phase-catalyzed reaction of PtCl with NaS02R, 4 or the insertion of S02 into a platinum-alkyl bond1635 as shown in equations (481)-(483). When PtCl(S02R)L2 is treated with silver ion the 0,0 -bonded chelate complex (173) is formed (equation 484). 

A wide range of alkyl- and aryl-hydroxo-bis(tertiary phosphine) complexes of platinum(II) has been prepared now (17, 18, 19, 20, 21), generally by the route shown in Equation 4 or some variant of it... 

In common with other platinum metals, an important area of ruthenium chemistry involves trialkyl- and triarylphosphines, and the corresponding phosphites. An extremely wide range of complexes is known, mainly of the II state, although compounds in the 0, III, and less commonly, IV state are known other ligands commonly associated with the PR3 group are halogens, alkyl and aryl groups, CO, NO, and alkenes as well as H and H2. Similar chemistry is found for osmium. 

Hydride complexes of palladium and platinum are almost invariably stabilized by phosphine ligands and play an important role in catalytic processes such as hydrogenation. Examples are Pt(H)ClL2 and Pt(H)2L2, as well as hydrido alkyls and aryls, trans,-Pt(H)(R)L2. There are cis and trans isomers. A typical reaction is the insertion of alkenes and alkynes into the Pt—H bond 33... 

The mechanism of the isocyanide insertion has been examined for the coordinatively unsaturated platinum(II) alkyls and aryls 127) it involves an ionic intermediate in which both R NC and R are coordinated to the metal [Eq. (40)]. Coordinatively saturated alkyl complexes are believed... 

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