How many complexes are low spin type ?
[Co(NH₃)₆]³⁺, [CoF₆]³⁻, [Fe(CN)₆]⁴⁻, [Fe(H₂O)₆]²⁺, [Cr(gly)₃]⁰, [CoBr₂Cl₂]²⁻

Question

How many complexes are low spin type ? [Co(NH₃)₆]³⁺, [CoF₆]³⁻, [Fe(CN)₆]⁴⁻, [Fe(H₂O)₆]²⁺, [Cr(gly)₃]⁰, [CoBr₂Cl₂]²⁻

TestHub · Accepted Answer

There are 2 low-spin complexes among the given choices: $[C o (N H_{3})_{6}]^{3 +}$ and $[F e (CN)_{6}]^{4 -}$ .

$[C o (N H_{3})_{6}]^{3 +}$ : $C o^{3 +}$ is a $d^{6}$ ion, and NH₃ acts as a strong-field ligand (SFL), forcing electrons to pair up ( $t_{2 g}^{6} e_{g}^{0}$ ).

$[F e (CN)_{6}]^{4 -}$ : $F e^{2 +}$ is a $d^{6}$ ion, and $C N^{-}$ is a SFL, which causes pairing and results in a low-spin configuration ( $t_{2 g}^{6} e_{g}^{0}$ ).

Others: $[C o F_{6}]^{3 -}$ , $[F e (H_{2} O)_{6}]^{2 +}$ , and $[C o B r_{2} C l_{4}]^{2 -}$ contain weak-field ligands (high-spin), while $[C r (g l y)_{3}]^{0}$ is a $d^{3}$ system with no spin distinction.

Chemistry - Coordination Chemistry Question with Solution | TestHub

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