Synthesis of Co(PhC(O)CHC(CH3)NC6H4-p-OCH3)2 (6b).
Co(OAc)2·4H2O (1.87 g, 7.50 mmol) was dissolved and heated in
10 mL MeOH. N-p-anisyl b-ketoamine 6a (4.01 g, 15.0 mmol) was
added to the stirred reaction solution to give a suspension. KOH
(0.846 g 15.1 mmol) was dissolved in MeOH (8 mL) and added
dropwise to the stirred reaction solution over 5 min. The solution
first turned green, but after 5 min generated an orange precipitate
that was collected by filtration to yield 1.25 g (28% yield) of 6b. The
orange solid was recrystallised from CH2Cl2 layered with hexanes
to afford X-ray quality crystals as deep red needles.
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Elemental analysis found: C 69.03, H 5.51, N 4.99; calc. for
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14.76 (1H), 11.85 (1H), 10.02 (2H), 3.35 (3H), -21.20 (3H), -32.49
(1H), -50.56 (2H). Magnetic moment m = 4.5 mB.
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A series of bis(b-ketoaminato)cobalt(II) complexes was prepared,
bearing various substituents on the N-bound aryl rings. All
compounds exhibited tetrahedral geometry as determined by X-
ray crystallography, and as consistent with their magnetic sus-
ceptibilities and 1H NMR spectra. The electrochemical oxidation
potentials were found to be sensitive to variation in ortho- and
para- substitution on the N-bound aryl rings, consistent with a
significant contribution to each compound’s HOMO from the
corresponding carbon atoms as determined by DFT calculations.
Acknowledgements
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We thank Dr. Yun Ling of The University of British Columbia
for elemental analyses, and both NSERC of Canada and UBC
Okanagan for funding.
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