Isotope effects in arene C-H bond activation by ((C/sub 5/Me/sub 5/)Rh(PMe/sub 3/))

Journal Article · Wed Aug 06 00:00:00 EDT 1986 · J. Am. Chem. Soc.; (United States)

OSTI ID:5585441

Jones, W D; Feher, F J

The isotope effects involved in the activation of arene C-H bonds by the intermediate ((C/sub 5/Me/sub 5/)Rh(PMe/sub 3/)) have been investigated. The ratio k/sub H/k/sub D/ for coordination to a double bond in benzene (the rate-determining step of arene activation) is found to be 1.05 (6), whereas k/sub H//k/sub D/ = 1.4 for the second step in which the C-H bond of the coordinated arene undergoes oxidative addition. The isotope effect K/sub H/D/ for the equilibrium between the more stable phenyl hydride complex (C/sub 5/Me/sub 5/)Rh(PMe/sub 3/)(C/sub 6/D/sub 5/)H and the complex containing hydrogen in the ortho position of the phenyl ring (C/sub 5/Me/sub 5/)Rh(PMe/sub 3/)(o-C/sub 6/D/sub 4/H)D shows a preference for hydrogen (vs. deuterium) on the metal of 2.7. The kinetic isotope effect for reductive elimination and dissociation of m-xylene from (C/sub 5/Me/sub 5/)Rh(PMe/sub 3/)(3,5-C/sub 6/H/sub 3/Me/sub 2/)H vs. (C/sub 5/Me/sub 5/)Rh(PMe/sub 3/)(3,5-C/sub 6/H/sub 3/Me/sub 2/)D is found to be inverse, with k/sub H//k/sub D/ = 0.51. Analysis of the data for the deuterated benzene derivatives confirms that the kinetic isotope for the reductive elimination step is inverse. Attempts to prepare the complex (C/sub 5/Me/sub 5/)Rh(PMe/sub 3/)(CH/sub 3/)D by reduction of ((C/sub 5/Me/sub 5/)Rh(PMe/sub 3/)(CH/sub 3/)(THF))/sup +/ with (DBEt/sub 3/)/sup -/ resulted in the formation of both (C/sub 5/Me/sub 5/)Rh(PMe/sub 3/)(CH/sub 3/)D and (C/sub 5/Me/sub 5/)Rh(PMe/sub 3/)(CH/sub 2/D)H.

• Research Organization: Univ. of Rochester, NY
• DOE Contract Number: AC02-83ER13095
• OSTI ID: 5585441
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 108:16; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ACTIVATION ENERGY
CHEMICAL BONDS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMPLEXES
DATA
DEUTERIUM COMPOUNDS
ENERGY
EXPERIMENTAL DATA
HYDROGEN COMPOUNDS
INFORMATION
ISOTOPE EFFECTS
KINETICS
NUMERICAL DATA
ORGANIC COMPOUNDS
PHOSPHORUS COMPLEXES
REACTION INTERMEDIATES
REACTION KINETICS
REDUCTION
RHODIUM COMPLEXES
TRANSITION ELEMENT COMPLEXES