Coordination Compounds – important questions for Boards 2027
CBSE Class 12 Chemistry
Write the IUPAC name of K[Zn(OH)₄].
Answer
The IUPAC name is potassium tetrahydroxidozincate(III). The complex is anionic, so zinc takes the suffix “-ate”; its oxidation state is +3.
According to Werner’s theory, which type of valence is normally ionisable and satisfied by negative ions?
Answer
Primary valences are normally ionisable and are satisfied by negative ions, unlike non-ionisable secondary valences.
What are coordination polyhedra? Name three common geometries of transition-metal coordination compounds.
Answer
Coordination polyhedra are the characteristic spatial arrangements of groups bound to a metal through secondary linkages. Common transition-metal geometries are octahedral, tetrahedral and square planar. These arrangements correspond to different coordination numbers.
State the order in which a coordination compound is named, including how the ligands are ordered. Explain how anionic ligands and ligand counts are represented in the name, including when bis, tris or tetrakis is used.
Answer
1. The cation is named first, followed by the coordination entity. Within the entity, ligand names precede the central atom or ion and are listed alphabetically. 2. Anionic ligand names end in –o, while neutral and cationic ligand names generally remain unchanged, except for special names such as aqua and ammine. 3. Prefixes mono, di and tri show ligand counts; bis, tris or tetrakis are used when a ligand name contains a numerical prefix, with that ligand name in parentheses.
(a) Classify isomerism in coordination compounds into its two broad types, and distinguish them. (2) (b) Describe the geometrical arrangements that give rise to cis/trans and fac/mer isomerism, and state why geometrical isomerism is not possible in tetrahedral complexes with unidentate ligands. (2) (c) Define optical isomers. (1)
Answer
1. Bonds and spatial arrangement — Structural isomers have different bonds; stereoisomers have the same chemical formula and chemical bonds but different spatial arrangements. 2. Cis/trans arrangement — Cis isomers have identical ligands adjacent to one another, while trans isomers have them opposite one another in square-planar or octahedral complexes. 3. Fac/mer arrangement — In octahedral complexes with three identical ligands, fac isomers have the ligands on one face; mer isomers have them along a meridian plane. 4. Tetrahedral geometry — Unidentate ligands have the same relative positions to one another in tetrahedral complexes; therefore, these complexes do not show geometrical isomerism. 5. Optical isomers — Optical isomers are mirror images that cannot be superimposed on one another; they are called enantiomers.
According to Werner’s theory, a metal’s secondary valence is: (A) variable and ionisable (B) fixed for a metal and equal to its coordination number (C) always satisfied only by negative ions (D) independent of its coordination number
Answer locked. Unlock all answers on SmartKalike
Define a ligand. How is the coordination number of a metal ion determined when a complex contains multidentate ligands?
Answer locked. Unlock all answers on SmartKalike
Explain why tetrahedral complexes are rarely low spin. Also state the types of metal–carbonyl bonding interactions involved in bonding between a metal and CO.
Answer locked. Unlock all answers on SmartKalike
(a) Compare the crystal-field splitting in tetrahedral and octahedral complexes, including the relationship between Δt and Δo. (2) (b) Why are tetrahedral complexes rarely low spin? (1) (c) Explain how the colour of a coordination complex is related to the colour of light it absorbs. (2)
Answer locked. Unlock all answers on SmartKalike
What is a coordination entity?
Answer locked. Unlock all answers on SmartKalike
23 more probable questions in this chapter, every one with a full answer.
Unlock all answers on SmartKalike