Complex X of composition \(\mathrm{Cr}(\mathrm{H}_{2}\mathrm{O})_{6}\mathrm{Cl}_{n}\) has a spin only magnetic moment of 3.83 BM. It reacts with \(\mathrm{AgNO}_{3}\) and shows geometrical isomerism. The IUPAC nomenclature of X is:

(A) Dichloridotetraaqua chromium (IV) chloride dihydrate

(C) Tetraaquadichlorido chromium (IV) chloride dihydrate

(D) Hexaaqua chromium (III) chloride

JEE Main · 2020 · 09 Jan 2020 · Shift 1 · Coordination Compounds

Complex X of composition

Cr (H_{2} O)_{6} Cl_{n}

has a spin only magnetic moment of 3.83 BM. It reacts with

AgNO_{3}

and shows geometrical isomerism. The IUPAC nomenclature of X is:

(A)Dichloridotetraaqua chromium (IV) chloride dihydrate
(B)Tetraaquadichlorido chromium (III) chloride dihydrate✓ Correct
(C)Tetraaquadichlorido chromium (IV) chloride dihydrate
(D)Hexaaqua chromium (III) chloride

Answer: (B)

Solution

A spin-only moment of

3.83

BM points to three unpaired electrons, since

3 \cdot 5 \approx 3.87

, which means

C r^{3 +}

in a

3 d^{3}

configuration, so the complex is

Cr (H_{2} O)_{6} C l_{3}

in composition. Because it gives a precipitate with

AgN O_{3}

, showing free chloride, and displays cis-trans isomerism, two chlorides must lie inside the coordination sphere and one outside, with two water molecules displaced:

[Cr (H_{2} O)_{4} C l_{2}] Cl \cdot 2 H_{2} O

. Its name is tetraaquadichlorido chromium (III) chloride dihydrate.

JEE Main · 2020 · 09 Jan 2020 · Shift 1 · Single correct option

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JEE Main · 2020 · 09 Jan 2020 · Shift 1 · Coordination Compounds

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