Issue 23, 2010

Synthesis and structure of mono-, bi- and trimetallic amine-bis(phenolate) cobalt(ii) complexes

Abstract

A series of cobalt(II) amine-bis(phenolate) complexes has been prepared and characterized. The protonated tripodal tetradentate ligand precursors; dimethylaminoethylamino-N,N-bis(2-methylene-4-tert-butyl-6-methylphenol), H2[O2NN′]BuMeNMe2, dimethylaminoethylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenol), H2[O2NN′]BuBuNMe2, diethylaminoethylamino-N,N-bis(2-methylene-4,6-di-tert-amylphenol), H2[O2NN′]AmAmNEt2 and 2-pyridylamino-N,N-bis(2-methylene-4,6-di-tert-amylphenol), H2[O2NN′]AmAmPy; were reacted with cobaltous acetate tetrahydrate under varying conditions to afford a range of monometallic, bimetallic and trimetallic species. An unusual four coordinate complex Co[O2NN′]AmAmNEt2 containing CoII in a trigonal monopyramidal environment was structurally characterized, whereas using a less sterically demanding ligand a series of five coordinate complexes Co[O2NN′]BuBuNMe2(L) (L = H2O, CH3OH, (CH3)2C[double bond, length as m-dash]O, propylene oxide) containing CoII in a trigonal bipyramidal environment was prepared. A new angular structural parameter related to τ is defined, where τ′ may be used to compare complexes with trigonal monopyramidal structures. In contrast, ligands containing a pendant pyridyl donor afford dimeric species including {Co(μ-CH3OH)[O2NN′]AmAmPy}2. In the absence of base and in the presence of excess cobaltous acetate, trimetallic complexes were isolated containing a central CoII in an octahedral environment coordinated to four CH3OH and two bridging acetate ligands between two Co[O2NN′] fragments with CoII in a trigonal bipyramidal setting. The paramagnetic CoII complexes reported were also characterized by UV-vis spectroscopy, mass spectrometry, cyclic voltammetry and magnetic measurements.

Graphical abstract: Synthesis and structure of mono-, bi- and trimetallic amine-bis(phenolate) cobalt(ii) complexes

Supplementary files

Article information

Article type
Paper
Submitted
11 Feb 2010
Accepted
19 Apr 2010
First published
17 May 2010

Dalton Trans., 2010,39, 5462-5477

Synthesis and structure of mono-, bi- and trimetallic amine-bis(phenolate) cobalt(II) complexes

U. K. Das, J. Bobak, C. Fowler, S. E. Hann, C. F. Petten, L. N. Dawe, A. Decken, F. M. Kerton and C. M. Kozak, Dalton Trans., 2010, 39, 5462 DOI: 10.1039/C002843F

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