JEE Advanced 2024 · Paper 1 · Chemistry Q13

ChemistryInteger+4Question 47 of 51

Among the following complexes, the total number of diamagnetic species is _____.

$\ce{[Mn(NH3)6]^3+}$ , $\ce{[MnCl6]^3-}$ , $\ce{[FeF6]^3-}$ , $\ce{[CoF6]^3-}$ , $\ce{[Fe(NH3)6]^3+}$ , and $\ce{[Co(en)3]^3+}$

[Given, atomic number: Mn = 25, Fe = 26, Co = 27; en = $\ce{H2NCH2CH2NH2}$ ]

Your answer

Answer and worked solution

Official answer: 1

Complex	Metal ion	Field	Unpaired e⁻
$\ce{[Mn(NH3)6]^3+}$	$d^4$	strong-ish	2 (or 4)
$\ce{[MnCl6]^3-}$	$d^4$	weak	4
$\ce{[FeF6]^3-}$	$d^5$	weak	5
$\ce{[CoF6]^3-}$	$d^6$	weak	4
$\ce{[Fe(NH3)6]^3+}$	$d^5$	-	at least 1
$\ce{[Co(en)3]^3+}$	$d^6$	strong, $t_{2g}^6$	0

A $d^4$ or $d^5$ ion always has unpaired electrons in an octahedral field. Only $\ce{[Co(en)3]^3+}$ is diamagnetic: 1.

JEE Advanced 2024 · Paper 1, Chemistry question 13