Bis(tridentate)cobalt(III) complexes with diethylenetriamine and 4-Methyldiethylenetriamine [2,2'-Methyliminodi(ethylamine)]: assignment of geometric configurations by 1H and 13C N.M.R. spectroscopy

Searle, Graeme E., Lincoln, Stephen F., Keene, F. Richard, Teague, Stewart G., and Rowe, David G. (1977) Bis(tridentate)cobalt(III) complexes with diethylenetriamine and 4-Methyldiethylenetriamine [2,2'-Methyliminodi(ethylamine)]: assignment of geometric configurations by 1H and 13C N.M.R. spectroscopy. Australian Journal of Chemistry, 30 (6). pp. 1221-1228.

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Abstract

The new complexes symmetrical-facial-[Co(medien)₂]³⁺ and s-fac- [Co(dien)(medien)]³⁺ have been isolated. The ¹H NMR spectra of these complexes, the s-far, u-far and meridional isomers of [Co(dien)₂]³⁺, and u-fac-[Co(daes)₂]³⁺ show different splittings of the NH₂ proton resonances [dien = diethylenetriamine, medien = 4- methyldiethylenetriamine or 2,2'-methyliminodi(ethyl-amine), daes = di(2-aminoethyl) sulphide or 2,2'-thiodi(ethylamine)]. These splittings depend on the geometries of the complexes (different numbers of stereochemically distinct NH₂ groups), the particular chelated ligands (splittings due to coupling between the two protons on each NH₂ may vary with chelate ring conformational mobility), and the counter-anions (different extents of ion- association through hydrogen bonding). Thus NH₂ proton resonance signals may not always provide a reliable method for establishing molecular geometries. In contrast, the ¹³C NMR spectra of all these complexes are completely diagnostic of the detailed geometries, and most of the resonances observed have been assigned to particular carbon atoms.

Item ID: 22820
Item Type: Article (Refereed Research - C1)
ISSN: 1445-0038
Date Deposited: 14 Sep 2012 03:06
FoR Codes: 03 CHEMICAL SCIENCES > 0302 Inorganic Chemistry > 030207 Transition Metal Chemistry @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970103 Expanding Knowledge in the Chemical Sciences @ 100%
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