Butler, MJMJButlerWhite, AJPAJPWhiteCrimmin, MRMRCrimmin2018-05-042018-03-262018-05-042018-03-26Organometallics, 2018, 37 (6), pp.949-9560276-7333http://hdl.handle.net/10044/1/58877The reaction of a series of M·Zr heterobimetallic hydride complexes with dienes and alkynes has been investigated (M = Al, Zn, and Mg). Reaction of M·Zr with 1,5-cyclooctadiene led to diene isomerization to 1,3-cyclooctadiene, but for M = Zn also result in an on-metal diene-to-alkyne isomerization. The resulting cyclooctyne fragment is trapped 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 explored leading to the isolation of three new heterobimetallic slipped metallocyclopropene complexes. The mechanism of diene-to-alkyne isomerization was investigated through kinetics. While the reaction is first-order in Zn·Zr at high diene concentration and proceeds with ΔH‡ = +33.6 ± 0.7 kcal mol−1 , ΔS‡ = +23.2 ± 1.7 cal mol−1 K−1 , and ΔG⧧ 298 K = +26.7 ± 1.2 kcal mol−1 , the rate is dependent on the nature of the diene. The positive activation entropy is suggestive of involvement of a dissociative step. On the basis of DFT calculations, a heterobimetallic rebound mechanism for diene-to-alkyne isomerization has been proposed. This mechanism explains the origin of heterobimetallic control over selectivity: Mg---Zr complexes are too strongly bound to generate reactive fragments, while Al---Zr complexes are too weakly bound to compensate for the contrathermodynamic isomerization process. Zn---Zr complexes have favorable energetics for both dissociation and trapping steps.© 2018 American Chemical Society. This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes (https://pubs.acs.org/page/policy/authorchoice_termsofuse.html).Science & TechnologyPhysical SciencesChemistry, Inorganic & NuclearChemistry, OrganicChemistryZIEGLER-NATTA POLYMERIZATIONBETA-HYDROGEN ELIMINATIONACTIVATION STRAIN MODELC-H BORYLATIONAB-INITIOINSERTIONKINETICSDERIVATIVESOLEFINSETHYLENEJournal Articlehttps://www.dx.doi.org/10.1021/acs.organomet.7b00908EP/L011514/11520-6041