Synthesis and structure of mono-, bi- and trimetallic amine-bis(phenolate) cobalt(II) complexes.
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), H(2)[O(2)NN'](BuMeNMe2), dimethylaminoethylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenol), H(2)[O(2)NN'](BuBuNMe2), diethylaminoethylamino-N,N-bis(2-methylene-4,6-di-tert-amylphenol), H(2)[O(2)NN'](AmAmNEt2) and 2-pyridylamino-N,N-bis(2-methylene-4,6-di-tert-amylphenol), H(2)[O(2)NN'](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[O(2)NN'](AmAmNEt2) containing Co(II) in a trigonal monopyramidal environment was structurally characterized, whereas using a less sterically demanding ligand a series of five coordinate complexes Co[O(2)NN'](BuBuNMe2)(L) (L = H(2)O, CH(3)OH, (CH(3))(2)C[double bond, length as m-dash]O, propylene oxide) containing Co(II) in a trigonal bipyramidal environment was prepared. A new angular structural parameter related to tau is defined, where tau' may be used to compare complexes with trigonal monopyramidal structures. In contrast, ligands containing a pendant pyridyl donor afford dimeric species including {Co(mu-CH(3)OH)[O(2)NN'](AmAmPy)}(2). In the absence of base and in the presence of excess cobaltous acetate, trimetallic complexes were isolated containing a central Co(II) in an octahedral environment coordinated to four CH(3)OH and two bridging acetate ligands between two Co[O(2)NN'] fragments with Co(II) in a trigonal bipyramidal setting. The paramagnetic Co(II) complexes reported were also characterized by UV-vis spectroscopy, mass spectrometry, cyclic voltammetry and magnetic measurements.
Das
Uttam K
UK
Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland, Canada A1B 3X7.
Bobak
Julia
J
Fowler
Candace
C
Hann
Sarah E
SE
Petten
Chad F
CF
Dawe
Louise N
LN
Decken
Andreas
A
Kerton
Francesca M
FM
Kozak
Christopher M
CM
D000588:Amines / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry*; D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry; D018360:Crystallography, X-Ray; D055664:Electrochemical Techniques; D062385:Hydroxybenzoates / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D021241:Spectrometry, Mass, Electrospray Ionization; D013056:Spectrophotometry, Ultraviolet
D000588:Amines; D056831:Coordination Complexes; D062385:Hydroxybenzoates; D003035:Cobalt; C017616:phenolic acid