1,5-Cyclooctadiene platinum complexes

In all these reactions of chloroiridium complexes no insertion into the Ir — Cl bond was observed. For chloroplatinum(ii) complexes, however, such insertions have been observed. McCrindle and McAlees (1993) investigated the reaction of the dichloro(l,5-cyclooctadiene)platinum complex with three monosubstituted diazo-... 

A derivative of cyclopentyne has been trapped in a matrix. Although cycloheptyne and cyclohexyne have not been isolated at room temperatures, Pt(0) complexes of these compounds have been prepared and are stable." The smallest cyclic allene" so far isolated is l-/err-butyl-l,2-cyclooctadiene 107." The parent 1,2-cyclooctadiene has not been isolated. It has been shown to exist transiently, but rapidly dimerizes." " The presence of the rert-butyl group apparently prevents this. The transient existence of 1,2-cycloheptadiene has also been shown," and both 1,2-cyclooctadiene and 1,2-cycloheptadiene have been isolated in platinum complexes." 1,2-Cyclohexadiene has been trapped at low temperatures, and its structure has been proved by spectral smdies." Cyclic allenes in general are less strained than their acetylenic isomers." The cyclic cumulene 1,2,3-cyclononatriene has also been synthesized and is reasonably stable in solution at room temperature in the absence of air." ... 

A novel chiral dissymmetric chelating Hgand, the non-stabiUzed phosphonium ylide of (R)-BINAP 44, allowed in presence of [Rh(cod)Cl]2 the synthesis of a new type of eight-membered metallacycle, the stable rhodium(I) complex 45, interesting for its potential catalytic properties (Scheme 19) [81]. In contrast to the reactions of stabihzed ylides with cyclooctadienyl palladium or platinum complexes (see Scheme 20), the cyclooctadiene is not attacked by the carbanionic center. Notice that the reactions of ester-stabilized phosphonium ylides of BINAP with rhodium(I) (and also with palladium(II)) complexes lead to the formation of the corresponding chelated compounds but this time with an equilibrium be-... 

It is worth mentioning that, in a related study, a chiral platinum complex prepared from bis(cyclooctadiene) platinum [Pt(COD)2] (5 mol %) and (f ,f )-Me-DuPhos (6mol%), also catalyzed the reaction of 63 c efficiently to provide the product (R)-65c... 

Significant advances in organonickel chemistry followed the discovery of frtzws,fraws,fraws-(l,5,9-cyclododecatriene)nickel, Ni(cdt), and bis(l,5-cycloocta-diene)nickel Ni(cod)2 by Wilke et. al.1 In these and related compounds, in which only olefinic ligands are bonded to the nickel, the metal is especially reactive both in the synthesis of other compounds and in catalytic behavior. Extension of this chemistry to palladium and to platinum has hitherto been inhibited by the lack of convenient synthetic routes to zero-valent complexes of these metals in which mono- or diolefins are the only ligands. Here we described the synthesis of bis(l,5-cyclooctadiene)platinum, tris(ethylene)-platinum, and bis(ethylene)(tricyclohexylphosphine)platinum. The compound Pt(cod)2 (cod = 1,5-cyclooctadiene) was first reported by Muller and Goser,2 who prepared it by the following reaction sequence ... 

Cyclooctenyl and norbomenyl platinum complexes analogous to 14 and 15 have been proposed in the reactions of 1,5-cyclooctadiene and norborna-diene with HPt(N03)(PEt3)2 (57). 

Platinum complexes incorporating an optically active amine have been employed for resolution of racemic mixtures of optically active olefins by reaction of the olefin with dichloro-platinum(II). The differing solubility of the diastereoisomers permits separation by fractional crystallization and the olefin can be recovered by reaction of the complex with aqueous alkali cyanide. Using either (-f)-l-phenyl-2-aminopropane (Dexedrine) or (-f)- or (—)-a-phenyl-ethylamine. Cope and co-workers have resolved the optical isomers of trans double bond coordinated and, with (—)-phenylethyl-amine)dichloroplatinum(II), a bridged complex with each double bond coordinated to a different platinum atom. 

QH P, Phosphine, dimethylphenyl-, iron complex, 26 61 molybdenum complex, 27 11 osmium complex, 27 27 osmium-rhodium complex, 27 29 osmium-zirconium complex, 27 27 ruthenium complex, 26 273 CkH,2, 1,5-Cyclooctadiene, iridium complex, 26 122, 27 23 osmium-rhodium complex, 27 29 ruthenium complexes, 26 69-72, 253-256 CbH 20,PS, 2-Butenedioic acid, 2-(dimeth-ylphosphinothioyl)-, dimethyl ester, manganese complex, 26 163 ChH,4, Cyclooctene, platinum complex,... 

Of the new Pt catalysts reported since 1990 platinum complexes with new ligands and activators are noteworthy. Cyclodextrin complexes of platinum (as host-guest complexes) have been employed as hydrosilylation catalysts active at elevated temperature after releasing the guest compound [40]. Some other organic compounds have recently been used as activators (ligands) of Pt complexes, e. g., unsaturated secondary and tertiary alcohols and silylated unsaturated alcohols [41], alkadiynes, cyclooctadiene [42], and vinylnorbomene as well as quinones and methylnaphthoquinones [43]. 

Platinum vapour also has been observed to react with unsaturated compounds [286]. With propene and but-l-ene, compounds of undetermined structure are produced. Reaction with 1,5-cyclooctadiene produces b/s(l,5-cyclooctadiene) platinum(O), while reaction with allyl chloride yields the tetranuclear complex [PtCl(C3Hs)] 4. 

Erkey and co-workers [59-61] prepared Pt- and Ru-doped carbon aerogels using a supercritical deposition method. This involved dissolution of an organometallic precursor in a supercritical fluid and the exposure of a solid substrate to this solution. After impregnation of the support with the metal precursor, it was converted to the metal form by different methods. Dimethyl(l,5-cyclooctadiene) platinum(ll) was used as a precursor for Pt [59,60], and two different Ru complexes, trisacetylacetonate Ru(lll) and Ru(cod)(tmhd)2, were used for Ru [61], Monolithic organic and carbon aerogels... 

CgH,2, 1,5-Cyclooctadiene, iridium complex, 26 122 nickel complex, 28 94 osmium-rhodium complex, 27 29 palladium and platinum complexes, 28 346-348... 

Yamago developed a conceptually different synthetic route and demonstrated the selective synthesis of [8]CPP, which was the smallest CPP prepared at that time (Scheme 6.2c) [16]. The synthesis utilized the cis coordination of bisaryl platinum complexes as a structural motif for making a cyclic structure, and platinum square 14 was prepared by transmetallation of 4,4 -bisstannylated biphenyl 13c (X = SnMe3) and Pt(cod)Cl2 (cod refers to 1,5-cyclooctadiene). Compound 14 was also prepared stepwise by transmetallation of 13c to bisplatinum 13d and subsequent reaction between 13c,d. Once 14 was formed, ligand exchange from cod to dppf [dppf refers to l,3-bis(diphenylphosphino)ferrocene] and subsequent reductive elimination of platinum by employing bromine afforded [8] CPP. 

Dichloro(l,5-cyclooctadiene)platinum(II) may be prepared from hexa-chloroplatinic acid, or by heating bis(benzonitrile)dichloroplatinum(II) in 1,5-cyclooctadiene at 14S°C for 5 min, or from potassium tetra-chloroplatinate(2-). The complex [PtCl2(CgHi2)] has a very low solubility in the reaction mixture and must be finely ground to ensure complete reaction. The olefins 1,5-cyclooctadiene, bicyclo[2.2.1]hept-2-ene(2-norbomeneX and 1,3,5,7-cyclooctatetraene and all solvents should be dried and freshly distilled under nitrogen. In particular, peroxide-free diethyl ether is first dried over sodium wire and then distilled under nitrogen from sodium-benzophenone. 

N2Br2RuC22H22, Ruthenium(II), bis(benzonitrile)dibromo(q -1,5-cyclooctadiene)-, 26 71 N2C2HB, 1,2-Ethanediamine, chromium complex, resolution of, 26 24, 27, 28 platinum complexes, 27 314, 315... 

Other tris(olefin)platinum(0) complexes (where olefin represents a strained olefin such as bicyclo[2.2.1]heptene, dicyclopentadiene, or trans-cyclooctene) may be similarly obtained by direct displacement of 1,5-cyclooctadiene, often in quantitative yield.6... 

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