Electronic effects on the {Beta}-alkyl migratory insertion reaction of para-substituted styrene methyl palladium complexes

Journal Article · Wed Mar 13 04:00:00 EST 1996 · Journal of the American Chemical Society

DOI:https://doi.org/10.1021/ja9527434· OSTI ID:249627

Rix, F C; Brookhart, M; White, P S ^[1]

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1. Univ. of North Carolina, Chapel Hill, NC (United States)

The {Beta}-methyl migratory insertion chemistry of a series of cis-coordinated styrene methyl complexes of palladium [(phen)Pd(CH{sub 3})(p-X-C{sub 6}H{sub 4}CH=CH{sub 2}){sup +} Ar{sub 4} B{sup -} (2X) (phen = 1,10-phenanthroline; X = CF{sub 3}, Cl, H, CH{sub 3}, OCH{sub 3}; Ar` = 3,5-(CF{sub 3}){sub 2}C{sub 6}H{sub 3})] has been investigated. Complexes 2X are prepared in situ from the addition of p-X-styrene to CD{sub 2}Cl{sub 2} solutions of (phen)Pd(CH{sub 3})(OEt{sub 2}){sup +}Ar`{sub 4}B{sup -} (1). The X-ray structure of 1 has been determined. The relative binding affinities of the p-X-styrenes of 2X have been determined for the equilibria p-X-C{sub 6}H{sub 4}CH=CH{sub 2} + 2H C{sub 6}H{sub 5}CH=CH{sub 2} + 2X at -66{degree}C. The electron-rich styrenes bind tightest to Pd: a Hammett plot of these equilibrium constants yields {rho}{sup p} = -2.2{+-}0.1 and r =0.999. The kinetic and thermodynamic data indicate that both the ground and transition-states are stabilized by electron-rich styrenes and, of the two, the substituent effects are greatest in the ground-states. Since the relative rates are determined by the relative differences in energy of the ground and transition states, the migratory insertion reaction of 2X is accelerated by styrenes bearing electron-withdrawing substituents. 72 refs., 6 figs., 10 tabs.

• DOE Contract Number: FG05-94ER14459
• OSTI ID: 249627
• Journal Information: Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 10 Vol. 118; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
AFFINITY
BINDING ENERGY
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
EXPERIMENTAL DATA
GROUND STATES
LABELLING
METHYL RADICALS
NMR SPECTRA
PALLADIUM COMPLEXES
STRUCTURAL CHEMICAL ANALYSIS
STYRENE
X-RAY DIFFRACTION