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• W1978772488 endingPage "5686" @default.
• W1978772488 startingPage "5674" @default.
• W1978772488 abstract "The pKa of the 18-electron complexes [Fe(η5-C5R5)(η6-C6Me6)][PF6] {1a[PF6] (R = H) and 1b[PF6] (R = Me)} and [Fe(η5-C5R5)(η6-C6H5CHPh2)][PF6] {1c[PF6]} have been determined by the direct method in DMSO using bases with known pKa values and found to be 12−14 pKa units lower than the pKa of the free arenes, illustrating the electron-withdrawing character of the CpFe+ and Cp*Fe+ groups. Access to the pKa values for 16-, 17-, 19-, and 20-electron iron-sandwich complexes of this type with various arene structures was available by means of thermodynamic diagrams using the standard redox potentials of the oxidation and reduction of the 18-electron cations 1+ and the deprotonated complexes 2. For instance, the pKa of the 19-electron iron complex 1a (43.5) is about the same as that of free C6Me6 (43−44) whereas that of 1b is even slightly higher (46.4). The pKas of the anionic 20-electron complexes 1a- and 1b- are 7 and 12 units, respectively, higher than that of C6Me6. The pKas of 12+ are around −10, whereas those of 1a3+ were estimated to be around −50. In summary, the pKas were determined for the five isostructural oxidation states FeIV to Fe0, those of FeIV being more than 110 pKa units lower than those of Fe0. The benzylic C−H bond dissociation energies (BDEs) of the 18-electron complexes have been determined by means of a thermodynamic cycle using the pKa values and standard oxidation potentials of the deprotonated forms measured in DMSO. These BDE values are between 81 and 86 kcal/mol, i.e. approximately the same as that of the free arene. The benzylic C−H BDEs in the 19- and 20-electron complexes 1 and 1- have been determined using other thermodynamic diagrams and are 20 kcal/mol lower than in the 18-electron complexes, indicating the ease of these H-atom abstraction reactions. This trend is well taken into account by the fact that the valence shells of the metals are one unit closer to 18 in the products resulting from H-atom abstraction than in the starting paramagnetic complexes. For the 17-electron complexes, the BDEs were estimated to be only between 47 and 51 kcal/mol. We propose this stabilization of the corresponding dicationic C−H activated species to be due to coordination of the exocyclic double bond reminiscent of the structure of ferrocenyl carbonium cations." @default.
• W1978772488 created "2016-06-24" @default.
• W1978772488 creator A5033565884 @default.
• W1978772488 creator A5071668591 @default.
• W1978772488 creator A5081744015 @default.
• W1978772488 creator A5088277096 @default.
• W1978772488 date "1999-06-01" @default.
• W1978772488 modified "2023-10-14" @default.
• W1978772488 title "Thermodynamics of C−H Activation in Multiple Oxidation States: Comparison of Benzylic C−H Acidities and C−H Bond Dissociation Energies in the Isostructural 16−20-Electron Complexes [Fe<i>^x</i>(η⁵-C₅R₅)(η⁶-arene)]<i>ⁿ</i>, <i>x</i> = 0−IV, R = H or Me, <i>n</i> = −1 to +3" @default.
• W1978772488 cites W107423236 @default.
• W1978772488 cites W1534150946 @default.
• W1978772488 cites W1963689858 @default.
• W1978772488 cites W1963755483 @default.
• W1978772488 cites W1965807513 @default.
• W1978772488 cites W1967924479 @default.
• W1978772488 cites W1970799480 @default.
• W1978772488 cites W1971804768 @default.
• W1978772488 cites W1972400761 @default.
• W1978772488 cites W1973157294 @default.
• W1978772488 cites W1974567286 @default.
• W1978772488 cites W1974716209 @default.
• W1978772488 cites W1975455294 @default.
• W1978772488 cites W1976431711 @default.
• W1978772488 cites W1981447946 @default.
• W1978772488 cites W1981975563 @default.
• W1978772488 cites W1985138031 @default.
• W1978772488 cites W1985355717 @default.
• W1978772488 cites W1986558015 @default.
• W1978772488 cites W1987961645 @default.
• W1978772488 cites W1991150377 @default.
• W1978772488 cites W1991412319 @default.
• W1978772488 cites W1991653595 @default.
• W1978772488 cites W1992485951 @default.
• W1978772488 cites W1992792731 @default.
• W1978772488 cites W1992902988 @default.
• W1978772488 cites W1992966637 @default.
• W1978772488 cites W1993530935 @default.
• W1978772488 cites W1995457654 @default.
• W1978772488 cites W1996220289 @default.
• W1978772488 cites W1996486385 @default.
• W1978772488 cites W2003021569 @default.
• W1978772488 cites W2004358862 @default.
• W1978772488 cites W2004490969 @default.
• W1978772488 cites W2005766343 @default.
• W1978772488 cites W2007916926 @default.
• W1978772488 cites W2009264259 @default.
• W1978772488 cites W2012191828 @default.
• W1978772488 cites W2013345764 @default.
• W1978772488 cites W2013578681 @default.
• W1978772488 cites W2015233937 @default.
• W1978772488 cites W2015414506 @default.
• W1978772488 cites W2017545638 @default.
• W1978772488 cites W2018308030 @default.
• W1978772488 cites W2018410335 @default.
• W1978772488 cites W2024328682 @default.
• W1978772488 cites W2024886019 @default.
• W1978772488 cites W2025285104 @default.
• W1978772488 cites W2026620997 @default.
• W1978772488 cites W2030958085 @default.
• W1978772488 cites W2031002761 @default.
• W1978772488 cites W2033110790 @default.
• W1978772488 cites W2033136910 @default.
• W1978772488 cites W2033796222 @default.
• W1978772488 cites W2038860808 @default.
• W1978772488 cites W2040299058 @default.
• W1978772488 cites W2044437889 @default.
• W1978772488 cites W2046203654 @default.
• W1978772488 cites W2048022307 @default.
• W1978772488 cites W2048868992 @default.
• W1978772488 cites W2049146010 @default.
• W1978772488 cites W2054421673 @default.
• W1978772488 cites W2055104603 @default.
• W1978772488 cites W2056943955 @default.
• W1978772488 cites W2059554532 @default.
• W1978772488 cites W2061487555 @default.
• W1978772488 cites W2063576003 @default.
• W1978772488 cites W2063965470 @default.
• W1978772488 cites W2065024363 @default.
• W1978772488 cites W2066671943 @default.
• W1978772488 cites W2068877344 @default.
• W1978772488 cites W2069162132 @default.
• W1978772488 cites W2072624193 @default.
• W1978772488 cites W2073628365 @default.
• W1978772488 cites W2075677403 @default.
• W1978772488 cites W2078203870 @default.
• W1978772488 cites W2080695096 @default.
• W1978772488 cites W2085376785 @default.
• W1978772488 cites W2087682719 @default.
• W1978772488 cites W2088540603 @default.
• W1978772488 cites W2091361937 @default.
• W1978772488 cites W2091696540 @default.
• W1978772488 cites W2091808919 @default.
• W1978772488 cites W2092011216 @default.
• W1978772488 cites W2095492850 @default.
• W1978772488 cites W2097708560 @default.
• W1978772488 cites W2101185742 @default.
• W1978772488 cites W2106572805 @default.
• W1978772488 cites W2114652517 @default.

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