Are cyclopentadienyl complexes more stable than their pyrrolyl analogues?

The bond dissociation enthalpies of η5-coordinated pyrrolyl and cyclopentadienyl complexes with group 4 metals, [M(η5-X)Cl3], are calculated by means of a thermochemical cycle combining DFT/B3LYP results and experimental data. The values obtained for D(M-Cp) and D(M-pyr) are very similar, suggesting that the known instability of pyrrolyl complexes, when compared to cyclopentadienyl analogues, should be caused by kinetic reasons.