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Chisholm MH, Choojun K, Chow AS, et al. THF exchange and molecular dynamics in the series (BDI)MgX(THF), where X = Bu(n), NEt2, and OBu(t) and BDI = 2-[(2,6-diisopropylphenyl)amino]-4-[(2,6-diisopropylphenyl)imino]pent-2-ene. Inorg Chem. 2013;52(19):11302-10doi: 10.1021/ic401559b.
Chisholm, M. H., Choojun, K., Chow, A. S., Fraenkel, G., & Gallucci, J. C. (2013). THF exchange and molecular dynamics in the series (BDI)MgX(THF), where X = Bu(n), NEt2, and OBu(t) and BDI = 2-[(2,6-diisopropylphenyl)amino]-4-[(2,6-diisopropylphenyl)imino]pent-2-ene. Inorganic chemistry, 52(19), 11302-10. https://doi.org/10.1021/ic401559b
Chisholm, Malcolm H, et al. "THF exchange and molecular dynamics in the series (BDI)MgX(THF), where X = Bu(n), NEt2, and OBu(t) and BDI = 2-[(2,6-diisopropylphenyl)amino]-4-[(2,6-diisopropylphenyl)imino]pent-2-ene." Inorganic chemistry vol. 52,19 (2013): 11302-10. doi: https://doi.org/10.1021/ic401559b
Chisholm MH, Choojun K, Chow AS, Fraenkel G, Gallucci JC. THF exchange and molecular dynamics in the series (BDI)MgX(THF), where X = Bu(n), NEt2, and OBu(t) and BDI = 2-[(2,6-diisopropylphenyl)amino]-4-[(2,6-diisopropylphenyl)imino]pent-2-ene. Inorg Chem. 2013 Oct 07;52(19):11302-10. doi: 10.1021/ic401559b. Epub 2013 Sep 25. PMID: 24066833.
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Inorg Chem. 2013 Oct 07;52(19):11302-10. doi: 10.1021/ic401559b. Epub 2013 Sep 25.

THF exchange and molecular dynamics in the series (BDI)MgX(THF), where X = Bu(n), NEt2, and OBu(t) and BDI = 2-[(2,6-diisopropylphenyl)amino]-4-[(2,6-diisopropylphenyl)imino]pent-2-ene.

Inorganic chemistry

Malcolm H Chisholm, Kittisak Choojun, Albert S Chow, Gideon Fraenkel, Judith C Gallucci

Affiliations

  1. Department of Chemistry and Biochemistry, The Ohio State University , 100 West 18th Avenue, Columbus, Ohio 43210, United States.

PMID: 24066833 DOI: 10.1021/ic401559b

Abstract

The complexes (BDI)MgX(THF), where X = Bu(n), NEt2, and OBu(t), are shown to undergo THF exchange at low added concentrations of THF by a dissociative mechanism: X = Bu(n), ΔH(#) (kcal mol(-1)) = 13.4 ± 0.4 and ΔS(#) (cal mol(-1) K(-1)) = 6.3 ± 1.6; X = NEt2, ΔH(#) (kcal mol(-1)) = 15.2 ± 0.5 and ΔS(#) (cal mol(-1) K(-1)) = 11.4 ± 2.3; X = OBu(t), ΔH(#) (kcal mol(-1)) = 16.4 ± 0.3 and ΔS(#) (cal mol(-1) K(-1)) = 9.5 ± 1.3. The apparent aryl group rotations involving the BDI ligands have, within experimental error, the same activation parameters as the THF dissociation, which suggests that the two are correlated involving a three coordinate reactive intermediate akin to what is well-known for related (BDI)ZnR compounds involving three-coordinate trigonal planar Zn(2+). At higher concentrations of THF for X = Bu(n) and OBu(t), but not for X = NEt2, the coalescence temperatures for apparent aryl group rotation are depressed from those of the pure compounds in toluene-d8, and evidence is presented that this correlates with an associative interchange process which becomes dominant in neat THF. We estimate the Ia mechanism to have activation parameters: ΔH(#) (kcal mol(-1)) = 5.4 ± 0.1 and ΔS(#) (cal mol(-1) K(-1)) = -20.9 ± 0.3 for X = Bu(n) and ΔH(#) (kcal mol(-1)) = 8.3 ± 0.8 and ΔS(#) (cal mol(-1) K(-1)) = -19.8 ± 3.0 for X = OBu(t). For the complex (BDI)MgBu(n)(2-MeTHF), the dissociative exchange with added 2-MeTHF occurs more readily than for its THF analogue, as expected for the more sterically demanding Lewis base O-donor: ΔH(#) (kcal mol(-1)) = 12.8 ± 0.5 and ΔS(#) (cal mol(-1) K(-1)) = 8.6 ± 1.8. At very low temperatures in toluene-d8, restricted rotation about the Mg-O(THF) bond is observed for the complexes where X = NEt2 and OBu(t) but not for the complex where X = Bu(n). These observations, which have been determined from dynamic NMR studies, are correlated with the reactivities of these complexes in solution.

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