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Suggest why backbonding strength decreases in...?
Suggest why the back bonding strength of these ligands decreases in the order C-Se > C-S > CO
I ask this since the donation is occuring into a lower pi* each time AND the repulsion from lp electrons will be significantly reduced since going down the group the lp will be held closer which would suggest a reversal in this trend. I considered the d block contraction for C-Se however this wouldn't explain it.
2 Answers
- ?Lv 78 years agoFavorite Answer
There is less C2pπ- Enpπ (E = Se, S, O) overlap going down Group 16. Consequently for CSe the πMOs are less stabilized than in CO and the π* MOs are likewise at a lower energy in CSe than in CO. Because the π* MOs are closer in energy to the filled 3d AOs (for example) there is better M3d→π*CSe back bonding.
