A 1H NMR study of the complex of cobalt(II) with 2,5,8,11-tetramethyl-2,5,8,11-tetraazadodecane in aerated aqueous solutions

Ivano Bertini; Luigi Messori; Gilad Golub; Haim Cohen; Dan Meyerstein

doi:10.1016/0020-1693(95)90038-8

A ¹H NMR study of the complex of cobalt(II) with 2,5,8,11-tetramethyl-2,5,8,11-tetraazadodecane in aerated aqueous solutions

Ivano Bertini
, Luigi Messori
, Gilad Golub
, Haim Cohen
, Dan Meyerstein

Department of Chemistry

Research output: Contribution to journal › Article › peer-review

17 Scopus citations

Abstract

The fully methylated open chain polyamine ligand 2,5,8,11-tetramethyl-2,5,8,11-tetraazadodecane forms a stable 1:1 complex with cobalt(II) over the pH range 8-9.5. The paramagnetic ¹H NMR spectrum of the complex exhibits a number of relatively narrow and nicely resolved isotropically shifted signals spread between 200 and -50 ppm. Saturation transfer experiments and the analysis of the temperature dependence of the ¹H NMR spectra provide information on the peculiar dynamic properties of this complex in solution; an assignment of all the paramagnetically shifted signals to methylene and methyl protons is proposed. From the analysis of the spectroscopic results it is argued that over the investigated pH range the geometry of the complex is pseudooctahedral with all the four nitrogen atoms coordinated equatorially to the metal. This complex is not oxidized by dioxygen in contrast to its unmethyled form and other cobalt(II) complexes with amine ligands.

Original language	English
Pages (from-to)	5-8
Number of pages	4
Journal	Inorganica Chimica Acta
Volume	235
Issue number	1-2
DOIs	https://doi.org/10.1016/0020-1693(95)90038-8
State	Published - 1 Jan 1995

Keywords

Cobalt complexes
Polyamine ligand complexes
Proton NMR study

ASJC Scopus subject areas

Physical and Theoretical Chemistry
Inorganic Chemistry
Materials Chemistry

Access to Document

10.1016/0020-1693(95)90038-8

Cite this

@article{d75dcd2816ff456a9f13b89976a5a61a,

title = "A 1H NMR study of the complex of cobalt(II) with 2,5,8,11-tetramethyl-2,5,8,11-tetraazadodecane in aerated aqueous solutions",

abstract = "The fully methylated open chain polyamine ligand 2,5,8,11-tetramethyl-2,5,8,11-tetraazadodecane forms a stable 1:1 complex with cobalt(II) over the pH range 8-9.5. The paramagnetic 1H NMR spectrum of the complex exhibits a number of relatively narrow and nicely resolved isotropically shifted signals spread between 200 and -50 ppm. Saturation transfer experiments and the analysis of the temperature dependence of the 1H NMR spectra provide information on the peculiar dynamic properties of this complex in solution; an assignment of all the paramagnetically shifted signals to methylene and methyl protons is proposed. From the analysis of the spectroscopic results it is argued that over the investigated pH range the geometry of the complex is pseudooctahedral with all the four nitrogen atoms coordinated equatorially to the metal. This complex is not oxidized by dioxygen in contrast to its unmethyled form and other cobalt(II) complexes with amine ligands.",

keywords = "Cobalt complexes, Polyamine ligand complexes, Proton NMR study",

author = "Ivano Bertini and Luigi Messori and Gilad Golub and Haim Cohen and Dan Meyerstein",

year = "1995",

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doi = "10.1016/0020-1693(95)90038-8",

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journal = "Inorganica Chimica Acta",

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T1 - A 1H NMR study of the complex of cobalt(II) with 2,5,8,11-tetramethyl-2,5,8,11-tetraazadodecane in aerated aqueous solutions

AU - Bertini, Ivano

AU - Messori, Luigi

AU - Golub, Gilad

AU - Cohen, Haim

AU - Meyerstein, Dan

PY - 1995/1/1

Y1 - 1995/1/1

N2 - The fully methylated open chain polyamine ligand 2,5,8,11-tetramethyl-2,5,8,11-tetraazadodecane forms a stable 1:1 complex with cobalt(II) over the pH range 8-9.5. The paramagnetic 1H NMR spectrum of the complex exhibits a number of relatively narrow and nicely resolved isotropically shifted signals spread between 200 and -50 ppm. Saturation transfer experiments and the analysis of the temperature dependence of the 1H NMR spectra provide information on the peculiar dynamic properties of this complex in solution; an assignment of all the paramagnetically shifted signals to methylene and methyl protons is proposed. From the analysis of the spectroscopic results it is argued that over the investigated pH range the geometry of the complex is pseudooctahedral with all the four nitrogen atoms coordinated equatorially to the metal. This complex is not oxidized by dioxygen in contrast to its unmethyled form and other cobalt(II) complexes with amine ligands.

AB - The fully methylated open chain polyamine ligand 2,5,8,11-tetramethyl-2,5,8,11-tetraazadodecane forms a stable 1:1 complex with cobalt(II) over the pH range 8-9.5. The paramagnetic 1H NMR spectrum of the complex exhibits a number of relatively narrow and nicely resolved isotropically shifted signals spread between 200 and -50 ppm. Saturation transfer experiments and the analysis of the temperature dependence of the 1H NMR spectra provide information on the peculiar dynamic properties of this complex in solution; an assignment of all the paramagnetically shifted signals to methylene and methyl protons is proposed. From the analysis of the spectroscopic results it is argued that over the investigated pH range the geometry of the complex is pseudooctahedral with all the four nitrogen atoms coordinated equatorially to the metal. This complex is not oxidized by dioxygen in contrast to its unmethyled form and other cobalt(II) complexes with amine ligands.

KW - Cobalt complexes

KW - Polyamine ligand complexes

KW - Proton NMR study

UR - https://www.scopus.com/pages/publications/0002296836

U2 - 10.1016/0020-1693(95)90038-8

DO - 10.1016/0020-1693(95)90038-8

M3 - Article

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SN - 0020-1693

VL - 235

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EP - 8

JO - Inorganica Chimica Acta

JF - Inorganica Chimica Acta

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