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The knowledge of accurate bond strengths is a fundamental basis for a proper analysis of chemical reaction mechanisms. Quantum chemical calculations at different levels of theory have been used to investigate heterolytic Fe-O and Fe-S bond energies of (meta-substituted phenoxy)dicarbonyl(η5-cyclopentadienyl) iron [ m-G-C6H4OFp ( 1)] and (meta-substituted benzenethiolato)dicarbonyl(η5-cyclopentadienyl) iron [ m-G-C6H4SFp ( 2)] complexes. In this study, Fp is (η5-C5H5)Fe(CO)2, and G is NO2, CN, COMe, CO2Me, CF3, Br, Cl, F, H, Me, MeO, and NMe2. The results show that Tao-Perdew-Staroverov-Scuseria and Becke's power-series ansatz from 1997 with dispersion corrections functionals can provide the best price/performance ratio and accurate predictions of Δ Hhet(Fe-O)'s and Δ Hhet(Fe-S)'s. The excellent linear free energy relations [ r = 1.00 (g, 1e), 1.00 (g, 2b)] among the ΔΔ Hhet (Fe-O)'s and δΔ G0 of OH bonds of m-G-C6H4OH or ΔΔ Hhet(Fe-S)'s and Δp Ka's of SH bonds of m-G-C6H4SH imply that the governing structural factors for these bond scissions are similar. And, the linear correlations [ r = −0.97 (g, 1 g), −0.97 (g, 2 h)] among the ΔΔ Hhet (Fe-O)'s or ΔΔ Hhet(Fe-S)'s and the substituent σm constants show that these correlations are in accordance with Hammett linear free energy relationships. The inductive effects of these substituents and the basis set effects influence the accuracy of Δ Hhet(Fe-O)'s or Δ Hhet(Fe-S)'s. The ΔΔ Hhet(Fe-O)'s(g) (1) and ΔΔ Hhet(Fe-S)'s(g)(2) follow the capto-dative Principle. The substituent effects on the Fe-O bonds are much stronger than those on the less polar Fe-S bonds. Insight from this work may help the design of more effective catalytic processes. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The knowledge of accurate bond strengths is a fundamental basis for a proper analysis of chemical reaction mechanisms. Quantum chemical calculations at different levels of theory have been used to investigate heterolytic Feâ€'O and Feâ€'S bond energies of paraâ€substituted phenoxydicarbonyl( η5â€cyclopentadienyl) iron [ pâ€Gâ€C6H4O( η5â€C5H5)Fe(CO)2, abbreviated as pâ€Gâ€C6H4OFp ( 1), where G = NO2, CN, COMe, CO2Me, CF3, Br, Cl, F, H, Me, MeO, and NMe2] and paraâ€substituted benzenethiolatodicarbonyl( η5â€cyclopentadienyl) iron [ pâ€Gâ€C6H4S( η5â€C5H5)Fe(CO)2, abbreviated as pâ€Gâ€C6H4SFp ( 2)] complexes. The results show that BP86 and TPSSTPSS can provide the best price/performance ratio and more accurate predictions in the study of Î' Hhet(Feâ€'O)'s and Î' Hhet(Feâ€'S)'s. The excellent linear freeâ€energy relations [ r = 0.99 (g, 1a), 1.00 (g, 2b)] among the Î'Î' Hhet (Feâ€'O)'s and Î'p ka's of Oâ€'H bonds of pâ€Gâ€C6H4OH or Î'Î' Hhet(Feâ€S)'s and Î'p ka's of Sâ€'H bonds of pâ€Gâ€C6H4SH imply that the governing structural factors for these bond scissions are similar. And the linear correlations [ r = âˆ'0.99 (g, 1g), âˆ'0.98 (g, 2h)] among the Î'Î' Hhet (Feâ€O)'s or Î'Î' Hhet(Feâ€S)'s and the substituent σpâˆ' constants show that these correlations are in accordance with Hammett linear freeâ€energy relationships. The polar effects of these substituents and the basis set effects influence the accuracy of Î' Hhet(Feâ€'O)'s or Î' Hhet(Feâ€'S)'s. Î'Î' Hhet(Feâ€'O)'s(g) ( 1) and Î'Î' Hhet(Feâ€'S)'s(g)( 2) follow the Captoâ€dative principle. The substituent effects on the Feâ€'O bonds are much stronger than those on the less polar Feâ€'S bonds. Insight from this work may help the design of more effective catalytic processes. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]