Chemistry - Coordination Chemistry Question with Solution | TestHub
The correct statements from following are
(A) The strength of anionic ligands can be explained by crystal field theory.
(B) Valence bond theory does not give a quantitative interpretation of kinetic stability of coordination compounds.
(C) The hybridisation involved in formation of [Ni(CN)4 ]2- complex is dsp2 .
(D) The number of possible isomer(s) of cis-[PtCl2(en)2 ]2+ is one.
The number of possible from the options given below :
Options:
Answer:
Solution:
(A) Crystal field theory (CFT) explains ligand strength based on electrostatic interactions, but it does not fully account for the strength of anionic ligands, especially strong field ones like CN⁻. Molecular orbital theory (MOT) provides a more complete explanation. Thus, statement (A) is incorrect.
(B) Valence bond theory (VBT) focuses on bonding and hybridization but does not offer a quantitative measure for the kinetic stability (lability or inertness) of coordination compounds. This is a limitation of VBT. Thus, statement (B) is correct.
(C) In [Ni(CN)₄]²⁻, Ni is in the +2 oxidation state (d⁸ configuration). CN⁻ is a strong field ligand, causing pairing of electrons. The hybridization is dsp², leading to a square planar geometry. Thus, statement (C) is correct.
(D) The complex cis-[PtCl₂(en)₂]²⁺ has a coordination number of 6 (Pt²⁺ is d⁸, but here it's octahedral due to the ligands). The 'en' (ethylenediamine) is a bidentate ligand. The 'cis' prefix indicates a specific isomer. For a complex of the type [Ma₂b₂] (where 'a' is a monodentate ligand and 'b' is a bidentate ligand), if 'a' is cis, then there are two possible isomers: cis and trans. However, the given complex is cis-[PtCl₂(en)₂]²⁺. This complex can exhibit optical isomerism. The cis isomer is chiral and exists as a pair of enantiomers (d and l forms). Therefore, there are two possible isomers for cis-[PtCl₂(en)₂]²⁺ (the cis-d and cis-l forms). Thus, statement (D) is incorrect.
Therefore, the correct statements are (B) and (C).
The final answer is