Q133 / 200 · MHT CET - Medical 2026 (21 April Shift 1) · Chemistry
Identify the anionic sphere complex from following.
- ATriamminetrinitrocobalt(III)
- BTetramminecopper(II) ion
- Correct answerCSodium hexanitrocobaltate(III)
- DPentacarbonyliron(0)
Solution
An anionic sphere complex is a coordination compound in which the complex ion (coordination sphere) carries a net negative charge.
Triamminetrinitrocobalt(III) is $[Co(NH_3)_3(NO_2)_3]$. The net charge on the complex is $+3 + 3(0) + 3(-1) = 0$. It is a neutral complex.
Tetramminecopper(II) ion is $[Cu(NH_3)_4]^{2+}$. The net charge on the complex is $+2 + 4(0) = +2$. It is a cationic complex.
Sodium hexanitrocobaltate(III) is $Na_3[Co(NO_2)_6]$. The complex ion is $[Co(NO_2)_6]^{3-}$. The net charge on the complex sphere is $+3 + 6(-1) = -3$. It is an anionic complex.
Pentacarbonyliron(0) is $[Fe(CO)_5]$. The net charge on the complex is $0 + 5(0) = 0$. It is a neutral complex.
Therefore, Sodium hexanitrocobaltate(III) contains an anionic coordination sphere.
Answer: Sodium hexanitrocobaltate(III)
Triamminetrinitrocobalt(III) is $[Co(NH_3)_3(NO_2)_3]$. The net charge on the complex is $+3 + 3(0) + 3(-1) = 0$. It is a neutral complex.
Tetramminecopper(II) ion is $[Cu(NH_3)_4]^{2+}$. The net charge on the complex is $+2 + 4(0) = +2$. It is a cationic complex.
Sodium hexanitrocobaltate(III) is $Na_3[Co(NO_2)_6]$. The complex ion is $[Co(NO_2)_6]^{3-}$. The net charge on the complex sphere is $+3 + 6(-1) = -3$. It is an anionic complex.
Pentacarbonyliron(0) is $[Fe(CO)_5]$. The net charge on the complex is $0 + 5(0) = 0$. It is a neutral complex.
Therefore, Sodium hexanitrocobaltate(III) contains an anionic coordination sphere.
Answer: Sodium hexanitrocobaltate(III)
Hence, the correct answer is option: 'C'.