Stability of the metal–carbon–halogen system. Part I. The preparation and properties of some platinum(<scp>II</scp>)- and palladium(<scp>II</scp>)-vinyl complexes

Johnson, Brian F. G.; Lewis, J.; Jones, J. David; Taylor, K. A.

doi:10.1039/dt9740000034

Cited by 25 publications

(10 citation statements)

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“…A compound of this type is trans-PtC1( CCl=C( H) C1) ( PMePh2) 2, 34 Therefore these compounds do not (i) eliminate HC1, (ii) isomerize by a dipolar mechanism of the type shown in eq 5, or (iii) undergo isomerization by a reversible cis-trans @-hydrogen elimination sequence. Finally we note a number of closely related vinylplatinum(I1) compounds can be prepared in one isomeric form.…”

Section: ~~U~s-p~b~(cd~ch)(pe~~)~~' Cis-pt(cd2chzch2ch3)2-(pph3)23mentioning

confidence: 99%

Reactions of alkynyl- and alkenylplatinum(II) compounds. 2. Study of the reaction between anhydrous hydrogen chloride and diethynylbis(dimethylphenylphosphine)platinum(II). Evidence for platinum-stabilized vinyl cations

Bell¹,

Chisholm²

1977

Inorg. Chem.

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AIC60800Strans-Pt(CdH),L,, I, reacts with anhydrous HCl(1 equiv) in the solvents CDCI, and CD2CI2 to give trans-RC1(C=CH)L2, V, and acetylene by way of a sequence of reactions involving trans-Pt(C=CH)(CC1=CH2)L2, 11, trat~s-Pt(CCl=CH,)~L~, 111, and trans-PtC1(CC1=CH2)L2, IV, where L = PMezPh. I and 111 exist in equilibrium with 11: 211 e I + 111, K N 1. ~~~~S -P~( C C I = C H~)~L~, 111, decomposes slowly, both in solution and in the melt, to give trans-PtC1(CC1=CH2)L2, IV, and acetylene. These reactions involve platinum(I1)-promoted HC1 addition-elimination processes. I11 and IV react with the tertiary amines Me,N and proton sponge to give I and V, respectively. The rates of elimination of HC1 from 11-IV in benzene are approximately zeroth order in base concentration and show an isotope ratio kH/kD E 3. The rate of HC1 elimination from the CC1=CH2 moiety is greatly dependent on the solvent, c6H~N02 > CDC1, -CD2C12 >> C6D6 -CC14, and is dependent on the nature of the [XPt] moiety to which it is bound: PtCSCH -PtCCI=CH, > PtCl >> Pt+C(Me)OMe. Elimination of HCI from the chlorovinyl ligands PtCCl=C(D(H))H(D) proceeds with no apparent stereochemical preference; elimination of HCI from PtCCl=C(Me(H))H(Me) occurs preferentially from the trans-PtC=CH isomer. trans-Pt(CC1=CH2)2L2 reacts with MeOD to give trans-[Pt(CC1=CH2)(C(CD3)OMe)Lz]+ which has been isolated as a hexafluorophosphate salt. A stepwise addition-elimination sequence involving the platinum-stabilized vinyl cation PtC+=CH2 is proposed to account for all of these observations t Pt-CXH, ZPt-C=CH, ZPt-CGCH + HCl I c1 c1-The molecular structure of 111 deduced from x-ray studies reveals a long vinylic C-CI bond distance, 1.809 (6) A, and a large Pt-C-C angle, 133.5'. The decomposition of 111 to give IV and acetylene occurs much faster in CDzClz and CDC13 than in benzene. The reaction 111 -IV + HCsCH is slow relative to HCl elimination from 111, irrespective of the solvent.A mixture of I11 and 111-d4 decomposes in the melt and in solution to give a mixture of acetylenedo, -dl, and -d2. An isotope ratio kH/kD N 1.9 has been found for the reaction I11 -IV + acetylene. A number of mechanisms which could yield acetylene in the above reaction are discussed. These findings are compared to solvolysis and elimination reactions of aryl-substituted vinyl compounds, Ar(X)C=CH2, where X = CI, Br, or CF3S03. Platinum(f1) is thus shown to greatly activate the a-coordinated unsaturated organic ligand.

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Section: ~~U~s-p~b~(cd~ch)(pe~~)~~' Cis-pt(cd2chzch2ch3)2-(pph3)23mentioning

confidence: 99%

Reactions of alkynyl- and alkenylplatinum(II) compounds. 2. Study of the reaction between anhydrous hydrogen chloride and diethynylbis(dimethylphenylphosphine)platinum(II). Evidence for platinum-stabilized vinyl cations

Bell¹,

Chisholm²

1977

Inorg. Chem.

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“…The disposition of platinum arid hydrogen in the alkenyl function may be determined from the magnitude of 3J(Pr-H,,), for \vliich it has been shown (7,(17)(18)(19) that the order observed is trans > cis >> geinina!. However, it has zlso been found (16) that the value of 3J(Pt-H,.)…”

Section: Stereochemistry Of Reaction Productsmentioning

confidence: 98%

Chemistry of metal hydrides. Part XIX. Stereochemical changes at platinum during the insertion of acetylenes with platinum(II) hydrides

Clark¹,

Fiess²,

Wong³

1977

Can. J. Chem.

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The reactions of trans-[PtH(PEt3)2(acetone)]+ and trans-[PtH(PEt3)2(CO)]+ with a variety of acetylenes are described. The geometries of the products with respect to the platinum centre and to the stereochemistry of the alkenyl group have been determined on the basis of their 1H nmr parameters. For reactions with the cation containing acetone, and particularly from a variable temperature 1H nmr study of its reaction with 2-butyne in the presence of water, the insertion pathway is shown to be entirely analogous to that for olefin insertion, involving an initial displacement of the trans ligand by acetylene, isomerization to a cis-like intermediate, migratory insertion rearrangement, and re-combination with an appropriate ligand to give either cis or trans platinum products. The insertion pathway with the carbonyl cation is dependent on the nature of the acetylene; for non-activated or weakly activated acetylenes insertion occurs via five-coordinate intermediates, but with strongly activated acetylenes, the same mechanism as with the acetone cation appears to occur, involving reversible loss of carbon monoxide.

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“…Thus, by using Pd(PPh 3 ) 4 or Ni(PPh 3 ) 4 as catalysts, Linstrumelle et al 100 showed that the cross-coupling reaction with alkylmagnesium chlorides occurs selectively (isomeric purity ª 95-99%) at the monosubstituted site of the trichloroethene. 41,101,102 This reaction offered an efficient route for the preparation of 2-alkyl-1,1-dichloroethene derivatives 53 which are useful intermediates in organic synthesis. However, when the reaction was performed with arylmagnesium bromides in the presence of PdCl 2 (dppb) as catalyst, Minato and co-workers 103 reported that a selective substitution of chlorine atom occurs on the disubstituted carbon, thus providing (Z)-1-aryl-1,2dichloroethene compounds 54 (Scheme 51).…”

Section: Scheme 50mentioning

confidence: 99%

1,2-Dihalogenalkenes: Useful Linchpins to Unsaturated Compounds via Palladium or Nickel Catalysis

Alami¹,

Peyrat²,

Brion³

2000

Synthesis

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The reactivity and synthetic applications of 1,2-dihalogenoalkenes towards the construction of unsaturated compounds are reviewed, covering the literature from 1956 to 2000. 1 Introduction 2 1,2-Dichloroethenes 2.1 Alkenes and 1-Chloroalkenes 2.2 Alkynes 2.3 Chloroenynes and Enediynes 2.4 Chlorodienes and Chlorotrienes 2.5 Polyenes 3 1,2-Dibromoethenes 4 Polyhalogenoalkenes 4.1 Alkenes and Halogenoalkenes 4.2 Alkynes and 1,3-Diynes 4.3 Enynes and Dienes 5 Conclusion

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Stability of the metal–carbon–halogen system. Part I. The preparation and properties of some platinum(II)- and palladium(II)-vinyl complexes

Cited by 25 publications

References 0 publications

Reactions of alkynyl- and alkenylplatinum(II) compounds. 2. Study of the reaction between anhydrous hydrogen chloride and diethynylbis(dimethylphenylphosphine)platinum(II). Evidence for platinum-stabilized vinyl cations

Reactions of alkynyl- and alkenylplatinum(II) compounds. 2. Study of the reaction between anhydrous hydrogen chloride and diethynylbis(dimethylphenylphosphine)platinum(II). Evidence for platinum-stabilized vinyl cations

Chemistry of metal hydrides. Part XIX. Stereochemical changes at platinum during the insertion of acetylenes with platinum(II) hydrides

1,2-Dihalogenalkenes: Useful Linchpins to Unsaturated Compounds via Palladium or Nickel Catalysis

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