Chemistry
Coordination Chemistry
319 Questions
Coordination chemistry focuses on coordination compounds, their structures, and their magnetic properties. The questions cover primary and secondary valencies, ligand types, and geometries of complexes. This topic is heavily tested in chemistry competitive exams and requires a good grasp of molecular structures.
primary and secondary valencycomplex geometriesligand field theorymagnetic properties of complexesisomerism in complexes
Coordination Chemistry Questions
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[Pt(py)(NH3)(NO2)(Cl)(Br)(I)]
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[Ir(C2O4)2Cl2]2-
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Trans-[Co(en)2Cl2]+
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[Ni(CO)4]
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None of these
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ionisation isomer
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linkage isomer
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coordination isomer
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hydrated isomer
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None of these
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[Ni(CN)4]2-, [Ni(Cl)4]2-
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[MnCl4]2-, [Ni(CO)4]
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[CuCl4]2-, [Cu(NH3)4]2+
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[Ni(CN)4]2-, [Ni(CO)4]
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None of these
B
Correct answer
Explanation
Correct option: One C2 axis and two vertical planes. Hence, point group is C2v.
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Fe (II)
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Mg (II)
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Cu (II)
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Cr (II)
A
Correct answer
Explanation
Hemoglobin contains iron (Fe) in its heme group, specifically in the +2 oxidation state (Fe(II) or Fe^2+). This iron center is what allows hemoglobin to bind and transport oxygen in the blood.
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[Cu (CN)4]2-
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[Pt (NH3)4]2+
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[Ni (CN)4]2-
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[PdCl4]2-
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2, 3 and 4 (Tetrahedral only).
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2, 4 (Tetrahedral only) and 6.
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2, 3 and 4 (Square planar only).
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2, 4 (Tetrahedral and square planar).
A
Correct answer
Explanation
Geometrical isomerism requires restricted ligand arrangement with cis/trans positioning. Tetrahedral complexes (CN=4) never show it because all ligands are adjacent. Linear (CN=2) and trigonal planar (CN=3) geometries lack the spatial arrangement needed. Square planar (CN=4) and octahedral (CN=6) complexes do show geometrical isomerism.
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Hydrogen
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Nitrogen
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Chlorine
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Cobalt
B
Correct answer
Explanation
In coordination compounds, donor atoms are ligand atoms that directly coordinate to the central metal ion. In [Co(NH3)6]Cl3, ammonia (NH3) ligands coordinate through nitrogen atoms. Chlorine is outside the coordination sphere as a counterion.
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[Co (NH3)3 Cl3]
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[Co (en)2 Cl2]+
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[Co (NH3)6] Cl3
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[Co (edta)]
C
Correct answer
Explanation
Optical activity requires non-superimposable mirror images (chirality). [Co(NH3)6]Cl3 has six identical ammonia ligands in octahedral geometry with perfect symmetry - it has multiple planes and axes of symmetry, making it achiral. The other compounds have asymmetric arrangements.
C
Correct answer
Explanation
Coordination number is the number of donor atoms directly bonded to the central metal ion. In [Ag(NH3)2]+, two ammonia ligands coordinate to silver, each through one nitrogen atom, giving CN=2.
D
Correct answer
Explanation
The oxalate ion (C2O4)2- is a bidentate ligand, coordinating through two oxygen atoms. In [Cr(C2O4)3]3-, three oxalate ligands each donate two electron pairs, giving 3×2=6 donor atoms bonded to chromium, so CN=6.
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Geometrical isomers have same physical and chemical properties.
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In cis-isomers, the two identical ligands occupy the positions diagonal to each other.
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In trans-isomers, the two identical ligands occupy the positions adjacent to each other.
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Geometrical isomerism is a type of stereo isomerism.
D
Correct answer
Explanation
Geometrical isomerism is a subtype of stereoisomerism where isomers differ in spatial arrangement but not in bonding connectivity. Geometrical isomers have different physical properties. Cis-isomers have identical ligands adjacent; trans-isomers have them opposite.
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Square planar
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Tetrahedral
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Trigonal planar
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Trigonal bipyramidal
D
Correct answer
Explanation
Fe(CO)5 is iron pentacarbonyl, a neutral coordination complex. With five CO ligands around a central metal ion, the only stable geometry that minimizes repulsion while satisfying the 18-electron rule is trigonal bipyramidal. Square planar would require only 4 ligands, tetrahedral geometry with 5 ligands is unstable, and trigonal planar only accommodates 3 ligands.
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[Co(NH3)5ONO]2+ and [Co(NH3)5NO2]2+
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[Co(NH3)4Cl2] NO2 and [Co(NH3)4 (Cl) NO2] Cl
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[Co(py)2 (H2O)2Cl2]Cl and [Co(py)2 (H2O)Cl3] H2O
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[Co(NH3)4 Cl2]NO2 and [Co(NH3)4(Cl)NO2]Cl
A
Correct answer
Explanation
Linkage isomerism occurs when ambidentate ligands can bind through different donor atoms. The nitrite ion (NO2-) is a classic ambidentate ligand that can bind through nitrogen (nitro: -NO2) or through oxygen (nitrito: -ONO). The two complexes [Co(NH3)5ONO]2+ and [Co(NH3)5NO2]2+ differ only in which atom binds to cobalt, making them linkage isomers.