Q17 of 43 Page 258

What is spectrochemical series? Explain the difference between a weak field ligand and a strong field ligand.

The strong ligands have higher splitting power of d orbitals of the central metal ion, whereas weak ligand has relatively lower splitting power of d orbitals of the central metal ion. The energy difference between t2g and eg sets of d orbitals is CFSE. The strength of the ligands depend on the magnitude of Δ . Strong ligands have larger value of CFSE and in case of weak ligands the CFSE values are smaller. The common ligands can be arranged in a series in the order of their decreasing field strength, as follows.

I_<Br -< SCN-< Cl-< F-< OH-< C2O42-< H2O< NCS-< py< NH3< en< bipy< o-phen< NO2-< CN-< CO.


This series depends on the power of splitting the d orbitals and is called spectrochemical series, The order of field strength of the common ligands neither depends on the geometry of the complex the nature of central metal ion.


More from this chapter

All 43 →
15

Discuss the nature of bonding in the following coordination entities on the basis of valence bond theory:


(i) [Fe(CN)6]4– (ii) [FeF6]3– (iii) [Co(C2O4)3]3– (iv) [CoF6]3–

 16

Draw figure to show the splitting of d orbitals in an octahedral crystal field.

 18

What is crystal field splitting energy? How does the magnitude of Δ0 decide the actual configuration of d orbitals in a coordination entity?

 19

[Cr(NH3)6]3+ is paramagnetic while [Ni(CN)4]2– is diamagnetic. Explain why?