1,what are strong and weak field ligands?2.how to determine the hybridisation of coordination compound.3.crystal field theory in details?

Dear rohini,

The weak field and strong field ligands are based on their capability of splitting. And are represented in Spectrochemical Series which is a derived list of ligands ordered by the size of the splitting Δ that they produce. It can be seen that the low-field ligands are all π-donors (such as I^-), the high field ligands are π-acceptors, such as CN^- and CO), and ligands such as H₂O and NH₃, which are neither strong or weak , are in the middle.

I⁻ < Br⁻ < S²⁻ < SCN⁻ < Cl⁻ < NO₃⁻ < N₃⁻ < F⁻ < OH⁻ < C₂O₄²⁻ < H₂O < NCS⁻ < CH₃CN < py (pyridine) < NH₃ < en (ethylenediamine) < bipy (2,2'-bipyridine) < phen (1,10-phenanthroline) < NO₂⁻ < PPh₃ < CN⁻ < CO

(Order of Increasing splitting weak field to strong field).

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