Stereochemical investigations of the mechanism of C-H BondActivation. Diastereomeric and Isotopic Scrambling in(Hydrido)alkyliridium Complexes
The diastereomeric complexes(RS),(SR)-((2,2-dimethylcyclopropyl)(Cp*) (PMe3)IrH) (2a) and(RR),(SS)-((2,2-dimethylcyclopropyl)(Cp*) (PMe3)IrH) (2b) and theiralpha-deuterated analogues (2a-alpha(d1), 2b-alpha(d1)) were synthesizedin racemic form and separated by low-temperature (-80 degrees C) columnchromatography. Thermolysis (140 degrees C) of diastereomerically pure 2aor 2b in C6D6 results in its interconversion to the other diastereomer.Thermolysis of the deuterium-labeled analogues 2a-alpha(d1) and2b-alpha(d1) resultsadditionally in scrambling of deuterium from thealpha-position of the dimethylcylopropyl ring to the metal hydrideposition. Diastereomer interconversion and isotopic scrambling occur atsimilar rates, which are faster than the rate observed for the reductiveelimination of dimethylcyclopropane and subsequent oxidative addition ofC6D6. Quantitative analysis of these rate data is reported. Thesimilarity of these rates is discussed in terms of a common intermediatemechanism involving a metal alkane (or "sigma-alkane") complex. Thismechanism is used as a basis far comparison of the rearrangementprocesses in the current iridium system and the previously reportedanalogous rhodium system.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Director, Office of Energy Research
- DOE Contract Number:
- DE-AC02-05CH11231
- OSTI ID:
- 895778
- Report Number(s):
- LBNL-42074
- Journal Information:
- Organometallics, Vol. 17, Issue 16; Related Information: Journal Publication Date: 08/03/1998
- Country of Publication:
- United States
- Language:
- English
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Diastereomeric and isotopic scrambling in (hydrido)alkyliridium complexes. Evidence for the presence of a common `alkane complex` intermediate
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