C-H insertion and. pi. -complex formation reactions of (/eta//sup 5/-C/sub 5/Me/sub 5/)(PMe/sub 3/)Ir with ethylene: an intra- and intermolecular isotope effect study
Thermolysis of the iridium cyclohexyl hydride (/eta//sup 5/-Me/sub 5/C/sub 5/)(PMe/sub 3/)Ir(C/sub 6/H/sub 11/)(H) at 130-160/degrees/C in cyclohexane in the presence of ethylene results in formation of the vinyl hydride (/eta//sup 5/-Me/sub 5/C/sub 5/)(PMe/sub 3/)Ir(HC /double bond/CH/sub 2/)(H) (1) and the ..pi..-complex (/eta//sub 5/-Me/sub 5/C/sub 5/)(PMe/sub 3/)Ir(H/sub 2/C /double bond/CH/sub 2/) (2) in a ratio of 2:1. Thermolysis of 1 in cyclohexane or benzene above 180/degrees/C results in quantitative conversion to 2. Thermolysis of (/eta//sub 5/-Me/sub 5/C/sub 5/)PMe/sub 3/Ir(C/sub 6/H/sub 11/)(H) in the presence of ethylene-d/sub 2/ results in insertion into both the C-H and the C-D bonds and allows determination of an intramolecular isotope effect: k/sub H//k/sub D/ = 1.18 /plus minus/ 0.03. Competition experiments involving ethylene and ethylene-d/sub 4/ allow determination of an intermolecular isotope effect for insertion into a C-H(D) bond: k/sub H//k/sub D/ = 1.49 /plus minus/ 0.08. The intermolecular isotope effect for formation of 2 was found to be 0.82 /plus minus/ 0.05. The different intra- and intermolecular isotope effects for C-H insertion require an intermediate different from the ..pi..-complex 2 on the reaction pathway leading to 1. Possible structures for this species are discussed. 44 references, 9 figures, 8 tables.
- Research Organization:
- Lawrence Berkeley National Lab., CA (USA)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5993672
- Journal Information:
- J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 110:17; ISSN JACSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
ALKANES
CHEMICAL REACTIONS
COMPLEXES
CYCLOALKANES
CYCLOHEXANE
DATA
DECOMPOSITION
DEUTERIUM
ELEMENTS
EXPERIMENTAL DATA
HYDRIDES
HYDROCARBONS
HYDROGEN
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
INFORMATION
IRIDIUM COMPLEXES
ISOTOPE EFFECTS
ISOTOPES
LIGHT NUCLEI
NONMETALS
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
STABLE ISOTOPES
TEMPERATURE EFFECTS
TRANSITION ELEMENT COMPLEXES