Imperial College London
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Professor Mark R. Crimmin

Faculty of Natural Sciences, Department of Chemistry

Professor of Organometallic Chemistry
 
 
 
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Contact

 

+44 (0)20 7594 2846m.crimmin Website

 
 
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Location

 

501NMolecular Sciences Research HubWhite City Campus

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Summary

 

Publications

Citation

BibTex format

@article{Butler:2018:10.1021/acs.organomet.7b00908,
author = {Butler, MJ and White, AJP and Crimmin, MR},
doi = {10.1021/acs.organomet.7b00908},
journal = {Organometallics},
pages = {949--956},
title = {Heterobimetallic rebound: a mechanism for diene-to-alkyne isomerization with M-Zr hydride complexes (M = Al, Zn, and Mg)},
url = {http://dx.doi.org/10.1021/acs.organomet.7b00908},
volume = {37},
year = {2018}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - The reaction of a series of M·Zr heterobimetallic hydride complexes withdienes and alkynes has been investigated (M = Al, Zn, and Mg). Reaction of M·Zr with1,5-cyclooctadiene led to diene isomerization to 1,3-cyclooctadiene, but for M = Zn alsoresult in an on-metal diene-to-alkyne isomerization. The resulting cyclooctyne fragment istrapped between Zr and Zn metals in a heterobimetallic species that does not form for M= Mg or Al. The scope of diene isomerization and alkyne trapping has been exploredleading to the isolation of three new heterobimetallic slipped metallocyclopropenecomplexes. The mechanism of diene-to-alkyne isomerization was investigated throughkinetics. While the reaction is first-order in Zn·Zr at high diene concentration andproceeds with ΔH‡ = +33.6 ± 0.7 kcal mol−1, ΔS‡ = +23.2 ± 1.7 cal mol−1 K−1, and ΔG298 K = +26.7 ± 1.2 kcal mol−1, the rateis dependent on the nature of the diene. The positive activation entropy is suggestive of involvement of a dissociative step. Onthe basis of DFT calculations, a heterobimetallic rebound mechanism for diene-to-alkyne isomerization has been proposed. Thismechanism explains the origin of heterobimetallic control over selectivity: Mg---Zr complexes are too strongly bound to generatereactive fragments, while Al---Zr complexes are too weakly bound to compensate for the contrathermodynamic isomerizationprocess. Zn---Zr complexes have favorable energetics for both dissociation and trapping steps.
AU  - Butler,MJ
AU  - White,AJP
AU  - Crimmin,MR
DO  - 10.1021/acs.organomet.7b00908
EP  - 956
PY  - 2018///
SN  - 0276-7333
SP  - 949
TI  - Heterobimetallic rebound: a mechanism for diene-to-alkyne isomerization with M-Zr hydride complexes (M = Al, Zn, and Mg)
T2  - Organometallics
UR  - http://dx.doi.org/10.1021/acs.organomet.7b00908
UR  - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000428610100016&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
UR  - http://hdl.handle.net/10044/1/58877
VL  - 37
ER  -
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