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Which of these statements about [ [ [ Co(CN) 6 ] 3 ā _6]^{3-} 6 ā ] 3 ā is true?
medium
Coordination Compounds
2015
chemistry
[Co(CN) 6 _6 6 ā ] 3 ā ^{3-} 3 ā has four unpaired electrons and will be in a low-spin configuration.
Explanation To solve this problem, we need to analyze the electronic configuration of the complex [ [ [ Co(CN) 6 ] 3 ā . _6]^{3-}.
\newline 6 ā ] 3 ā . 1. Determine the oxidation state of cobalt in [ [ [ Co(CN) 6 ] 3 ā : _6]^{3-}:
\newline 6 ā ] 3 ā :
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]
has four unpaired electrons and will be in a high-spin configuration.
[Co(CN) 6 _6 6 ā ] 3 ā ^{3-} 3 ā has no unpaired electrons and will be in a high-spin configuration.
[Co(CN) 6 _6 6 ā ] 3 ā ^{3-} 3 ā has no unpaired electrons and will be in a low-spin configuration.
⢠Let the oxidation state of Co be
⢠Each CN ligand carries a charge of
⢠The overall charge of the complex is
⢠Therefore, the equation is:
x + 6 ( ā 1 ) = ā 3. x + 6(-1) = -3.
\newline x + 6 ( ā 1 ) = ā 3. ⢠Solving for
x : x ā 6 = ā 3 x = + 3 x:
\newline x - 6 = -3
\newline x = +3
\newline x : x ā 6 = ā 3 x = + 3 2. Electronic configuration of Co
⢠The atomic number of cobalt (Co) is 27.
⢠The electronic configuration of neutral Co is
Ar
] ā 3 d 7 ā 4 s 2 . ] \, 3d^7 \, 4s^2.
\newline ] 3 d 7 4 s 2 . ⢠For Co
3 + , r e m o v e t h r e e e l e c t r o n s : t w o f r o m 4 s a n d o n e f r o m 3 d . ^{3+}, remove three electrons: two from 4s and one from 3d.
\newline 3 + , re m o v e t h reee l ec t ro n s : tw o f ro m 4 s an d o n e f ro m 3 d . ⢠The configuration becomes
Ar
] ā 3 d 6 . ] \, 3d^6.
\newline ] 3 d 6 . 3. Determine the spin state:
⢠CN
is a strong field ligand, which causes pairing of electrons.
⢠In a low-spin configuration, the 3d electrons will pair up.
⢠The 3d^6 configuration in a low-spin state results in all electrons being paired.
4. Analyze the options:
⢠Option 1: Four unpaired electrons and low-spin configuration. This is incorrect.
⢠Option 2: Four unpaired electrons and high-spin configuration. This is incorrect.
⢠Option 3: No unpaired electrons and high-spin configuration. This is incorrect.
⢠Option 4: No unpaired electrons and low-spin configuration. This is correct.
Therefore, the correct option is Option 4.