High-pressure methods as a tool in organometallic syntheses: facilitation of oxidative addition to platinum(II)

High-pressure (2 GPa) batch reactors now commercially available may offer substantial accelerations of organometallic syntheses, without resort to heating, when the activation process is multicentered or involves the generation and solvation of ions. As an example of the latter class of reactions, the kinetics of the oxidative additions of methyl and ethyl iodides (RI) to dimethyl(2,2′-bipyridine)platinum(II) in acetone have been studied over the pressure range 0–200 MPa. The volumes of activation ΔV1≠, if assumed to be constant over this range, are −11.7 ± 0.3 and −9.7 ± 0.7 cm3 mol−1, respectively, implying an acceleration of ca. 3000-fold for a batch synthesis of this sort at 2 GPa. However, a possible slight pressure dependence of ΔV1≠ may reduce this acceleration to ca. 1 000-fold. The ΔV1≠ data and the 500-fold retardation on going from R = Me to R = Et are consistent with an SN2 attack of Pt11 on the α-carbon in the alkyl iodides, forming I− and [RMe2Pt(bpy)]+. Key words: volumes of activation, hig...

[1]  R. Eldik,et al.  Volume Profile Analysis of Oxidative Addition to Palladium(II) and Reductive Elimination from Palladium(IV) , 1994 .

[2]  J. Vittal,et al.  Organoplatinum(IV) polymers and model complexes by oxidative addition of bromoacetate esters , 1993 .

[3]  R. Puddephatt,et al.  Oxidative addition as a route to organometallic polymers , 1992 .

[4]  M. J. Blandamer.  Chemical equilibria in solution : dependence of rate and equilibrium constants on temperature and pressure , 1992 .

[5]  W. L. Noble,et al.  Organic Synthesis at High Pressures , 1991 .

[6]  A. Ryabov.  Mechanisms of intramolecular activation of carbon-hydrogen bonds in transition-metal complexes , 1990 .

[7]  F.-G. Klärner.  Chemie unter Hochdruck Die Steuerung organisch‐chemischer Reaktionen mit hohem Druck , 1989 .

[8]  J. Jurczak,et al.  High pressure chemical synthesis , 1989 .

[9]  R. Puddephatt,et al.  Reactivity and mechanism in oxidative addition to palladium(II) and reductive elimination from palladium(IV) and an estimate of the palladium methyl bond energy , 1988 .

[10]  G. Lamprecht,et al.  Kinetics and mechanism of the oxidative addition of iodomethane to β-diketonatobis(triphenylphosphite)rhodium(I) complexes , 1988 .

[11]  R. Puddephatt,et al.  Cationic intermediates in oxidative addition reactions of alkyl halides to d8 complexes: evidence for the SN2 mechanism , 1987 .

[12]  T. Swaddle,et al.  The pressure dependence of rates of homolytic fission of metal-ligand bonds in aqueous solution , 1986 .

[13]  T. Swaddle,et al.  Pressure and temperature effects on the rates of concurrent homolytic and heterolytic decomposition pathways of aqueous (2-propyl- and 2-hydroxyprop-2-yl)chromium(III) ions , 1984 .

[14]  R. Puddephatt,et al.  Oxidation of dimethylplatinum(II) complexes with alcohols: Synthesis and characterization of alkoxoplatinum(IV) complexes , 1984 .

[15]  N. Isaacs.  Liquid Phase High Pressure Chemistry , 1981 .

[16]  R. Puddephatt,et al.  Preparation and electronic spectra of some alkyl- and aryl(2,2′-bipyridine)platinum(II) complexes , 1975 .

[17]  T. Swaddle,et al.  Mechanistic Information on the Aquations of Complexes of the Pentaamminecobalt(III) Series from Kinetic Studies at High Pressures , 1972 .

[18]  L. Manzer,et al.  A convenient synthesis for a variety of methyl- and trifluoromethylplatinum complexes , 1972 .

[19]  K. Weale.  Chemical Reactions at High Pressures , 1967 .