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The thermochemistry of organometallic complexes in solution and in the gas phase has been an area of increasing research interest. In this paper, the Fe-O and Fe-S homolytic bond dissociation energies [ΔHhomo(Fe-O)'s and ΔHhomo(Fe-S)'s] of two series of meta-substituted phenoxydicarbonyl(η5-cyclopentadienyl) iron [m-G-C6H4OFp (1)] and (meta-substituted benzenethiolato)dicarbonyl(η5-cyclopentadienyl) iron [m-G-C6H4SFp (2)] were studied using Hartree-Fock and density functional theory methods with large basis sets. In this study, Fp is (η5-C5H5)Fe(CO)2, and G are NO2, CN, COMe, CO2Me, CF3, Br, Cl, F, H, Me, MeO, and NMe2. The results show that Tao-Perdew-Staroverov-Scuseria and Minnesota 2006 functionals can provide the best price/performance ratio and accurate predictions of ΔHhomo(Fe-O)'s and ΔHhomo(Fe-S)'s. The polar effects of the meta substituents show that the dominant role to the magnitudes of ΔΔHhomo(Fe-O)'s or ΔΔHhomo(Fe-S)'s. sa·, sc· values for meta substituents are all related to polar effects. Spin-delocalization effects of the meta substituents in ΔΔHhomo(Fe-O)'s and ΔΔHhomo(Fe-S)'s are small but not necessarily zero. Molecular effects rather than ΔΔHhomo(Fe-O)'s and ΔΔHhomo(Fe-S)'s are more suitable indexes for the overall substituent effects on ΔHhomo(Fe-O)'s and ΔHhomo(Fe-S)'s. The meta substituent effects of meta-electron-withdrawing groups on the Fe-S bonds are much stronger than those on the Fe-O bonds. For meta-electron-donating groups, the meta substituent effects have the comparable magnitudes between series 1 and 2. ΔΔHhomo(Fe-O)'s (1) and ΔΔHhomo(Fe-S)'s (2) conform to the captodative principle. Insight from this work may help the design of more effective catalytic processes. [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]

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]

The nature and strength of metal-ligand bonds in organotransition-metal complexes is crucial to the understanding of organometallic reactions and catalysis. The Fe-N homolytic bond dissociation energies [ΔHhomo(Fe-N)'s] of two series of para-substituted Fp anilines p-G-C6H4NHFp [1] and p-G-C6H4N(COMe)Fp [2] were studied using the Hartree-Fock (HF) and the density functional theory methods with large basis sets. In this study, Fp is (η5-C5H5)Fe(CO)2 and G are N02, CN, COMe, CO2Me, CF3, Br, Cl, F, H, Me, MeO and NMe2. The results show that BP86 and TPSSTPSS can provide the best price/performance ratio and accurate predictions of ΔHhomo(Fe-N)'s. B3LYP can also satisfactorily predict the ɑ and remote substituent effects on AHhomo(Fe-N)'s [ΔΔHhomo(Fe-N)'s). The good correlations [r= 0.96 (g, 1), 0.99(g, 2)] of ΔΔHhomo(Fe-N)'s in series 1 and 2 with the substituent σp+ constants imply that the para-substituent effects on ΔHhomo(Fe-N)'s originate mainly from polar effects, but those on radical stability originate from both spin derealization and polar effects. ΔΔHhomo(Fe-N)'s(1,2) conform to the captodative principle. Insight from this work may help the design of more effective catalytic processes. [ABSTRACT FROM AUTHOR]

Knowledge of the strength of the metal-ligand bond breaking and formation is fundamental for an understanding of the thermodynamics underlying many important stoichiometric and catalytic organometallic reactions. Quantum chemical calculations at different levels of theory have been used to investigate heterolytic Fe-C bond energies of para-substituted benzyldicarbonyl(η5-cyclopentadienyl)iron, p-G-C6H4CH2Fp [1, G = NO2, CN, COMe, CO2Me, CF3, Br, Cl, F, H, Me, MeO, NMe2; Fp = (η5-C5H5)(CO)2Fe], and para-substituted α-cyanobenzyldicarbonyl(η5-cyclopentadienyl)iron, p-G-PANFp [2, PAN = C6H4CH(CN)]. The results show that BP86 and TPSSTPSS can provide the best price/performance ratio and more accurate predictions in the study of Δ Hhet(Fe-C)'s. The good linear correlations [ r = 0.98 (g, 1a), 0.99 (g, 2b)] between the substituent effects of heterolytic Fe-C bond energies [ΔΔ Hhet(Fe-C)'s] of series 1 and 2 and the differences of acidic dissociation constants (Δ pKa) of C-H bonds of p-G-C6H4CH3 and p-G-C6H4CH2CN imply that the governing structural factors for these bond scissions are similar. And the excellent linear correlations [ r = −1.00 (g, 1c), −0.99 (g, 2d)] between ΔΔ Hhet(Fe-C)'s and the substituent σp− constants show that these correlations are in accordance with Hammett linear free energy relationships. The polar effects of these substituents and the basis set effects influence the accuracy of Δ Hhet(Fe-C)'s. ΔΔ Hhet(Fe-C)'s(1, 2) follow the Capto-dative Principle. The detailed knowledge of the factors that determine the Fp-C bond strengths would greatly aid in understanding reactivity patterns in many processes. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Knowledge of the strength of the metal-ligand bond breaking and formation is fundamental for an understanding of the thermodynamics underlying many important stoichiometric and catalytic organometallic reactions. Quantum chemical calculations at different levels of theory have been used to investigate heterolytic Fe-C bond energies of para-substituted benzyldicarbonyl(η5-cyclopentadienyl)iron, p-G-C6H4CH2Fp [1, G = NO2, CN, COMe, CO2Me, CF3, Br, Cl, F, H, Me, MeO, NMe2; Fp = (η5-C5H5)(CO)2Fe], and para-substituted α-cyanobenzyldicarbonyl(η5-cyclopentadienyl)iron, p-G-PANFp [2, PAN = C6H4CH(CN)]. The results show that BP86 and TPSSTPSS can provide the best price/performance ratio and more accurate predictions in the study of Δ Hhet(Fe-C)'s. The good linear correlations [ r = 0.98 (g, 1a), 0.99 (g, 2b)] between the substituent effects of heterolytic Fe-C bond energies [ΔΔ Hhet(Fe-C)'s] of series 1 and 2 and the differences of acidic dissociation constants (Δ pKa) of C-H bonds of p-G-C6H4CH3 and p-G-C6H4CH2CN imply that the governing structural factors for these bond scissions are similar. And the excellent linear correlations [ r = −1.00 (g, 1c), −0.99 (g, 2d)] between ΔΔ Hhet(Fe-C)'s and the substituent σp− constants show that these correlations are in accordance with Hammett linear free energy relationships. The polar effects of these substituents and the basis set effects influence the accuracy of Δ Hhet(Fe-C)'s. ΔΔ Hhet(Fe-C)'s(1, 2) follow the Capto-dative Principle. The detailed knowledge of the factors that determine the Fp-C bond strengths would greatly aid in understanding reactivity patterns in many processes. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]