Chelation-controlled molecular morphology: aminal to imine rearrangements

Clegg, Jack K., Harrowfield, Jack, Kim, Yang, Lee, Young Hoon, Lehn, Jean-Marie, Lim, Woo Taik and Thuery, Pierre (2012) Chelation-controlled molecular morphology: aminal to imine rearrangements. Dalton Transactions, 41 15: 4335-4357. doi:10.1039/c2dt12250b

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Author Clegg, Jack K.
Harrowfield, Jack
Kim, Yang
Lee, Young Hoon
Lehn, Jean-Marie
Lim, Woo Taik
Thuery, Pierre
Title Chelation-controlled molecular morphology: aminal to imine rearrangements
Journal name Dalton Transactions   Check publisher's open access policy
ISSN 1477-9226
Publication date 2012-04
Sub-type Article (original research)
DOI 10.1039/c2dt12250b
Open Access Status File (Publisher version)
Volume 41
Issue 15
Start page 4335
End page 4357
Total pages 23
Place of publication Cambridge, United Kingdom
Publisher R S C Publications
Collection year 2012
Language eng
Abstract Reactions between the tripodal hydroxytriamine, 2,2-bis(aminomethyl)-3- aminopropan-1-ol, "hytame", and the isomeric pyridine aldehydes generate in all cases the tris(aminal) species based on a 1,3,5-triaza- adamantane skeleton. In all cases also, the product from water under basic conditions consists of an approximately 1:9 mixture of the triequatorial and monoaxial-diequatorial isomers. While all these tripyridyltriaza-adamantanes appear capable of acting as Lewis bases, in particular cases metal ion binding leads to a radical structural rearrangement. These cases involve the pyridine-2-aldehyde derivatives only and certain transition metal ions (notably Fe(ii)), and result in the conversion of the tris(aminal) into its isomeric tris(imine) form. This is apparently favoured because it can act as a hexadentate ligand towards a single metal ion, although kinetic influences are clearly important in this chemistry because template reactions of the triamine, pyridine-2-aldehyde and several metal ions give much better yields of the tris(imine) complex than do analogous rearrangement reactions. For the low-spin, kinetically inert Fe(ii) complex of the tris(imine), its formation is apparently so favourable that it is generated via aldehyde unit exchange when the aza-adamantanes derived from pyridine-3- and -4-aldehyde are heated with a mixture of Fe(ii) and pyridine-2-aldehyde. When the kinetically labile Zn(ii) complex is treated with EDTA, the metal ion is extracted but the released ligand does not undergo valence tautomerisation to what would be expected to be the triaxial isomer of the tripyridyltriaza-adamantane but instead rapidly undergoes partial hydrolysis before slowly forming the mixture of triequatorial and monoaxial-diequatorial isomers.
Keyword Crystal structure determination
Cyclotetrameric schiff base
Transition metal complexes
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status Non-UQ
Additional Notes First published on the web 29 Feruary 2012.

Document type: Journal Article
Sub-type: Article (original research)
Collections: Non HERDC
School of Chemistry and Molecular Biosciences
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