Mono- and trimetallic cobalt (II) and monometallic cobalth (III) amine-bis(phenolate) complexes: synthesis and structural properties

Das, Uttam K. (2010) Mono- and trimetallic cobalt (II) and monometallic cobalth (III) amine-bis(phenolate) complexes: synthesis and structural properties. Masters thesis, Memorial University of Newfoundland.

[img] [English] PDF - Accepted Version
Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.

Download (8Mb)

Abstract

This thesis describes the syntheses and structures of a series of monometallic and two trimetallic cobalt(II) amine-bis(phenolate) complexes. The protonated tripodal tetradentate ligand precursors dimethylaminoethylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenol), H₂[O₂NN']BuBuNMe2 and diethylaminoethylamino-N,N-bis(2-methylene-4,6-di-tert-amylphenol), H₂[O₂NN']AmAmNEt2 were reacted with cobaltous acetate tetrahydrate under varying conditions to afford both mono- and trimetallic species. X-ray crystallographic data of monometallic complexes [LCo[O₂NN']BuBuNMe2] (L = H₂O, CH₃OH, CH₃COCH₃, propylene oxide) showed that the Coᴵᴵ ion adopts a distorted trigonal bipyramidal coordination environment. 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 mono- and trimetallic Coᴵᴵ complexes reported were also characterized by UV-vis spectroscopy, mass spectrometry, cyclic voltammetry and magnetic measurements. The Coᴵᴵ ions in these complexes are all high-spin and the trimetallic species show very weak antiferromagnetic behaviour when modeled as a linear isotropic trimer. Electrochemical studies reveal that the redox processes are most likely ligand based but a metal centered redox process is also possible. These works have recently been published: 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. -- This thesis also describes several oxidation attempts and a successful synthesis of a monometallic Coᴵᴵᴵ amine-bis(phenolate) complex. The oxidation reactions were carried out using a variety of oxidizing agents under both aerobic and anaerobic conditions. However, only silver nitrate gave promising results in yielding a monometallic COᴵᴵᴵ amine-bis(phenolate) complex under aerobic conditions. The monometallic species was characterized by ¹H NMR spectroscopy, mass spectrometry, and elemental analysis.

Item Type: Thesis (Masters)
URI: http://research.library.mun.ca/id/eprint/9240
Item ID: 9240
Additional Information: Includes bibliographical references
Department(s): Science, Faculty of > Chemistry
Date: 2010
Date Type: Submission
Library of Congress Subject Heading: Cobalt compounds--Synthesis; Cobalt-ammonium compounds--Synthesis; Ligands

Actions (login required)

View Item View Item

Downloads

Downloads per month over the past year

View more statistics