Platinum complexes allyl

Allyl Complexes. Allyl complexes of thorium have been known since the 1960s and are usually stabilized by cyclopentadienyl ligands. AEyl complexes can be accessed via the interaction of a thorium haUde and an aHyl grignard. This synthetic method was utilized to obtain a rare example of a naked aHyl complex, Th(Tj -C2H )4 [144564-74-9] which decomposes at 0°C. This complex, when supported on dehydroxylated y-alumina, is an outstanding heterogeneous catalyst for arene hydrogenation and rivals the most active platinum metal catalysts in activity (17,18). 

Catalytic hydrogenation with platinum liberates the hydrocarbon from methylcobalamin (57) and from alkyl-Co-DMG complexes (161), but not from pentacyanides with primary alkyl, vinyl, or benzyl ligands, though the cr-allyl complex yields propylene (109). Sodium sand gives mixtures of hydrocarbons with the alkyl-Co-salen complexes (64). Dithioerythritol will liberate methane from a variety of methyl complexes [cobalamin, DMG, DMG-BF2, G, DPG, CHD, salen, and (DO)(DOH)pn] (156), as will 1,4-butanedithiol from the DMG complex (157), and certain unspecified thiols will reduce DMG complexes with substituted alkyl ligands (e.g., C0-CH2COOH ->CH3C00H) (163, 164). Reaction with thiols can also lead to the formation of thioethers (see Section C,3). 

Similar reactions can be utilized to prepare allyl complexes of platinum and palladium. In this case, the product can exist in two isomers as described earlier. Analogous reactions can be used to prepare the tris allyl complexes of several metals. 

DOT regulations for shipment, 6 301t molecular formula, 6 291t toxicity, 6 302t Allyl complexes of platinum, 19 656 of thorium, 24 773 Allyl diglycol carbonate, molecular formula, 6 305t Allyl ethers, 2 246... 

Both hydride cind jr-allyl complexes of these metals are well known in the -f-2 oxidation state (60), but neither hydride nor r-allyl complexes of platinum(IV) are known. 

A round-bottom flask consisting of a mixture of 1,4-bis-dimethylsilylbenzene (25.7 mmol), allyl methacrylate (51.4 mmol), 20 ml of toluene, and two drops of platinum divinyltetramethyldisiloxane complex dissolved in xylene were stirred at ambient temperature for 17 hours. The mixture was then loaded onto a silica gel column and eluted with a mixture of ethyl acetate/hexane, 20,80, respectively, and then concentrated and 7.8 g product isolated as a colorless oil having a viscosity of 136 cP. 

Although t/3-allyl complexes of platinum(II) are not rare, their occurrence is not as frequent as for -alkene complexes. This situation is reversed for palladium(II) where r 3-allyl complexes are very common, and much of modern organopalladium chemistry is becoming dominated by the reactivity of j)3-allyl complexes. 

Under certain conditions, platinum alkene complexes can be converted to jr-allyl complexes by hydrogen loss (equation 281).860 Allyl alcohol insertion into a platinum(II) carbonyl bond gives an allyloxycarbonylplatinum(II) intermediate which can be decarboxylated to form the jj3-allyl complex (equation 282).861,863... 

Phenalenium cations replace ethylene from P Cy XPPh to give cationic j3-allyl complexes (equation 283).863 Oxidative addition of Ph3CCI to give platinum(O) followed by treatment with Tl(acac) gives the i73-allyl complex of triphenylmethanide anion (equation 284).864,865... 

When the cyclopropyl platinum(II) complex dA-P(.(CHCH2CH2)2(PMe2Ph)2 is treated with HC1 then AgN03, the jr-allyl complex is formed (equation 285).866 -Allyl complexes can also be formed by insertion of alkenes into platinum-hydride bonds, and this reaction is discussed in Section 52.2.3.3. 

The structures of jj3-allyl complexes of platinum have been fully summarized by Hartley in Chapter 39 of Comprehensive Organometallic Chemistry . This article also details the NMR methods used to investigate fluxionality of the r/3-allyl ligand. 

Neutral ligands such as tertiary phosphines convert 3-allyl complexes of platinum(II) into the 1-allyl compound, and only in the presence of a large excess of added phosphine is the allyl ligand displaced. 

Dialkynyl ligands, in platinum(II) complexes, 8, 545 iV,iV-Diallylamine, via allyindium reagents, 9, 703-704 Diallyl clusters, in trirutheniums and triosmiums, 6, 773 gem-Diallyl esters, via indium-mediated allylation, 9, 677 Diallyl ethers, isomerization, 10, 90 Diamagnetic ylides, with gold(II), 2, 278 Diamides... 

Platinum(II) complexes with alkenyls, characteristics, 8, 471 with alkynyls, characteristics, 8, 538 into 7 3-allyl complexes, 8, 652 with arylenes, bisaryls, macrocycles, 8, 491 with aryls... 

Hydrosilylation of the protected allyl-glycoside 1 with the carbosilane 2 (by means of Silopren , a platinum-siloxane complex from Bayer AG) led via Si-C bond formation to a glycosidic carbosilane dendrimer (Fig. 4.42) [82]. 

JCD549, 1988JCD427, 19950M2538> are intermediate between those observed for /3-allyl complexes (ca. 4000 Hz for unsubstituted allyl platinum complexes, 3500—4000 Hz for 2-alkoxyallyl platinum complexes) and platinacyclobutane complexes (<2000 Hz) <1993OM3019>. These data clearly support a contribution from the 3-allyl-like coordination mode in metallacyclobutanone complexes. 

In addition to the ij3-allyl complexes of nickel, palladium, and platinum, we have also examined (i -allyl Rh and the (r)3-allyl)4M complexes of Zr, Mo, and W (70). The data for these complexes are collected in Table XI. 

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