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Question
Using crystal field theory, draw energy level diagram, write electronic configuration of the central metal atom/ion and determine the magnetic moment value in the following:
\[\ce{[CoF6]^{3-}, [Co(H2O)6]^{2+}, [Co(Cn)6]^{3-}}\]
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Solution
(1) \[\ce{[CoF6]^{3-}}\]:
\[\ce{Co^{3+} = 3d^6}\]
Number of unpaired electrons = 4
Magnetic moment = `sqrt(n(n + 2)) = sqrt(4(4 + 2))` = 4.9 BM
(ii) \[\ce{[Co(H2O)6]^{2+}}\]:
\[\ce{Co^{2+} = 3d^7}\]
Number of unpaired electrons = 3
Magnetic moment = `sqrt(3(3 + 2))` = 3.87 BM
(iii) \[\ce{[Co(CN)6]^{3-}}\]:
\[\ce{Co^{3+} = 3d^6}\]
No unpaired electrons so diamagnetic.
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