Structural variations in the coordination chemistry of amine-bis(phenolate) cobalt(II/III) complexes
作者:Lisa N. Saunders、Michelle E. Pratt、Sarah E. Hann、Louise N. Dawe、Andreas Decken、Francesca M. Kerton、Christopher M. Kozak
DOI:10.1016/j.poly.2012.07.082
日期:2012.10
A series of cobalt(II), cobalt(III) and mixed valence cobalt(II/III) compounds has been prepared and characterized. The protonated tripodal tetradentate ligand precursors (dimethylaminoethylamino-N, N-bis(2-methylene-4-tert-butyl-6-methylphenol), H-2[O2NN'](BuMeNMe2), dimethylaminoethylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenol), H-2[O2NN'](BuBbNMe2), and 2-pyridylamino-N,N-bis(2-methylene-4-tert-butyl-6-methylphenol), H-2[O2NN'](BuMePy) were reacted with cobaltous acetate tetrahydrate under varying conditions to afford a range of monometallic, bimetallic and trimetallic species. Monometallic compounds, 1 and 2, were obtained with pendant amine-containing ligands [O2NN'](BuMeNMe2) and [O2NN'](BuBuNMe2), respectively. Compound 1 is a trigonal bipyramidal Co-II acetone adduct, Co-II(OCMe2)[O2NN'](BuMeNMe2), and 2 is a distorted octahedral Co-III acetate complex, Co-II(OAc)[O2NN'](BuBuNMe2). A dimethoxo-bridged dicobalt(III) complex, 3, was obtained using the pyridyl group-containing ligand, [O2NN'](BuMePy), after oxidation in air of a methanol solution of Co[O2NN'](BuMePy)}(2). Two side-products, 4 and 5 were also obtained from this reaction. Complex 4 contains two octahedrally coordinated cobalt(III) atoms, each bonded to a tetradentate amine-bis(phenolate) ligand and bridged by one syn,syn eta(1):eta(1):mu(2) acetate ligand, and one hydroxide ligand. Complex 5 is a heterotrimetallic compound and consists of two Co[O2NN'](BuMePy) fragments, each bridged by a syn, anti eta(1):eta(1):mu(2) acetate ligand to a central Ca-II(HOMe)(4) fragment. Mixed valence Co-Co-III(II)-Co-III trimetallic complexes, 6 and 7, were obtained by reaction of H-2[O2NN'](BuMePy) or H-2[O2NN'](BuBuPy) ligands, respectively, with Co(OAc)(2)center dot 4H(2)O in 2:3 molar ratios in methanol under nitrogen followed by aerobic oxidation. Diethylamino-ethylamino-N,N-bis(2-methylene-4,6-di-tert-amylphenol), H-2[O2NN'](AmAmNEt2) was reacted with cobaltous chloride hexahydrate under acidic conditions to give the ionic compound H-3[O2NN'](AmAmNEt2)}(2)(+)[CoCl4](2-), 8. (C) 2012 Elsevier Ltd. All rights reserved.