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4`-Hydrazone derivatives of 2,2`: 6`,2``-terpyridine : protonation and substituent effects

Beves, Jonathon E. and Constable, Edwin C. and Housecroft, Catherine E. and Neuburger, Markus and Schaffner, Silvia and Zampese, Jennifer A.. (2008) 4`-Hydrazone derivatives of 2,2`: 6`,2``-terpyridine : protonation and substituent effects. European Journal of Organic Chemistry, 2008 (20). pp. 3569-3581.

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Official URL: http://edoc.unibas.ch/dok/A5248852

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Abstract

Four 4`-hydrazone derivatives of 2,2`:6`,2 ``-terpyridine which vary in their N- and C-substitution in the R`NN=CRPh unit have been prepared and structurally characterized. Protonation studies and solution behaviour of these compounds are described, as well as representative crystal structures of mono- and diprotonated derivatives. In the solid-state structures of each neutral compound, the tpy domain adopts the anticipated trans, trans- conformation, and intramolecular steric factors compete with pi-stacking effects to control the amount to which the C-phenyl substituent twists out of the plane of the tpy unit. When R` = H, the imine NH group engages in hydrogen bonding interactions in the solid state, except where R = Ph. In solution, variable temperature H-1 NMR spectroscopy shows that on going from R = Me to Ph (with R` = H), the barrier to rotation about the Cpy-Nimi_ bond increases; with R = R` = H, the hydrogen bonding capabilities of the solvent to the imine NH influence this dynamic process. In the N-methyl derivative (R = H and R` = Me), rotation about the C-py-N-imine bond is facile at room temperature. Protonation of the derivative with R = R` = H results in an increase in the activation barrier to rotation, consistent with a greater pi-contribution to the C-py-N-imine bond.
Faculties and Departments:05 Faculty of Science > Departement Chemie > Chemie > Anorganische Chemie (Constable)
05 Faculty of Science > Departement Chemie > Chemie > Anorganische Chemie (Housecroft)
UniBasel Contributors:Constable, Edwin Charles and Housecroft, Catherine Elizabeth
Item Type:Article, refereed
Publisher:Wiley
ISSN:1434-193X
e-ISSN:1099-0690
Note:Publication type according to Uni Basel Research Database: Journal article
Identification Number:
Last Modified:12 Apr 2017 06:40
Deposited On:22 Mar 2012 14:14

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