Acidity Enhancement of the Cyclopentadiene Ring by PH2 and AsH2 Substitution

摘要: The intrinsic acidity of cyclopentadiene and its PH 2 AsH derivatives has been investigated at the B3LYP/6-311+G(3df,2p)//B3LYP/6-31+G(d,p) level theory. calculated is consistent with available experimental data. Substitution one H atoms C(sp 3 )H group by leads to a significant enhancement 44 34 kJ mol -1 , respectively. This result balance two opposite effects: a) decrease in aromaticity anion on going from unsubstituted substituted forms, b) stabilization derivatives, through an interaction π-cloud ring X-H bonding orbitals or groups. renders substituent five membered stronger upon deprotonation, as reflected strengthening C-P C-As bonds.