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Question
Atomic number of \[\ce{Mn}\], \[\ce{Fe}\] and \[\ce{Co}\] are 25, 26 and 27 respectively. Which of the following inner orbital octahedral complex ions are diamagnetic?
(i) \[\ce{[Co(NH3)6]^{3+}}\]
(ii) \[\ce{[Mn(CN)6]^{3-}}\]
(iii) \[\ce{[Fe(CN)6]^{4-}}\]
(iv) \[\ce{[Fe(CN)6]^{3-}}\]
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Solution
(i) \[\ce{[Co(NH3)6]^{3+}}\]
(iii) \[\ce{[Fe(CN)6]^{4-}}\]
Explanation:
(i) Molecular orbital electronic configuration of \[\ce{Co^{3+}}\] in \[\ce{[Co(NH3)6]^{3+}}\] is
Number of unpaired electron = 0
Magnetic property = Diamagnetic
(ii) Molecular orbital electronic configuration of \[\ce{Mn^{3+}}\] in \[\ce{[Mn(CN)6]^{3-}}\]
Number of unpaired electron = 2
Magnetic property = Paramagnetic
(iii) Molecular orbital electronic configuration of \[\ce{Fe^{3+}}\] in \[\ce{[Fe(CN)6]^{4-}}\] is
Number of unpaired electron = 0
Magnetic property = Diamagnetic
(iv) Molecular orbital electronic configuration of \[\ce{Fe^{3+}}\] in \[\ce{[Fe(CN)6]^{3-}}\]
Number of unpaired electron = 1
Magnetic property = Paramagnetic
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