Die Struktur von [Fe(CO)4] - ein neues Kapitel einer langen Geschichte

Poliakoff, Martyn; Turner, James J.

doi:10.1002/1521-3757(20010803)113:15<2889::aid-ange2889>3.0.co;2-i

Cited by 8 publications

(2 citation statements)

References 27 publications

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“…A similar C 2 v structure was suggested for the singlet transient [Fe(CO) 4 ] generated by the photolysis of [Fe(CO) 5 ] and detected using ultrafast electron diffraction 62. 63 These differences between the analogous [Fe(PF 3 ) 4 ] and [Fe(CO) 4 ] may arise from the significantly greater steric demands of the PF 3 ligand. These demands can best be accommodated by distributing the PF 3 ligands in [Fe(PF 3 ) 4 ] as far apart as possible, corresponding to the vertices of a tetrahedron rather than those of the less symmetrical C 2 v polyhedron found in [Fe(CO) 4 ].…”

Section: Discussionsupporting

confidence: 57%

Unexpected Direct Iron‐Fluorine Bonds in Trifluorophosphane Iron Complexes: An Alternative to Bridging Trifluorophosphane and Difluorophosphido Groups

Zou

Xie

et al. 2008

Chemistry A European J

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The iron trifluorophosphane complexes [Fe(PF(3))(n)] (n=4, 5), [Fe(2)(PF(3))(n)] (n=8, 9), [H(2)Fe(PF(3))(4)], and [Fe(2)(PF(2))(2)(PF(3))(6)] have been studied by density functional theory. The lowest energy structures of [Fe(PF(3))(4)] and [Fe(PF(3))(5)] are a triplet tetrahedron and a singlet trigonal bipyramid, respectively. Both cis and trans octahedral structures were found for [H(2)Fe(PF(3))(4)] with the cis isomer lying lower in energy by approximately 10 kcal mol(-1). The lowest energy structure for [Fe(2)(PF(3))(8)] has two [Fe(PF(3))(4)] units linked only by an iron-iron bond of length 2.505 A consistent with the formal Fe=Fe double bond required to give both iron atoms the favored 18-electron configuration. In the lowest energy structure for [Fe(2)(PF(3))(9)] one of the iron atoms has inserted into a P-F bond of one of the PF(3) ligands to give a structure [(F(3)P)(4)Fe<--PF(2)Fe(F)(PF(3))(4)] with a bridging PF(2) group and a direct Fe-F bond. A bridging PF(3) group is found in a considerably higher energy [Fe(2)(PF(3))(9)] structure at approximately 30 kcal mol(-1) above the global minimum. However, this bridging PF(3) group keeps the two iron atoms too far apart (approximately 4 A) for the direct iron-iron bond required to give the iron atoms the favored 18-electron configuration. The preferred structure for [Fe(2)(PF(2))(2)(PF(3))(6)] has a bridging PF(2) group, as expected. However, this bridging PF(2) group bonds to one of the iron atoms through an P-Fe covalent bond and to the other iron through an F-->Fe dative bond, leaving an uncomplexed phosphorus lone pair.

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Section: Discussionsupporting

confidence: 57%

Unexpected Direct Iron‐Fluorine Bonds in Trifluorophosphane Iron Complexes: An Alternative to Bridging Trifluorophosphane and Difluorophosphido Groups

Zou

Xie

et al. 2008

Chemistry A European J

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“…Fragments of type Fe(CO) 3 (η 2 -olefin) 47,48 and Fe(CO) 3 (η 2 -diene) 49 have been suggested to possess a triplet ground state, by analogy with (naked) Fe(CO) 4 . , Hence one might argue that the electronic ground state of 3 is also a triplet rather than a singlet, as tacitly assumed in the above treatment . To address this point, a comparative calculation is performed for the triplet case .…”

Section: Resultsmentioning

confidence: 95%

A Novel Facet of Carbonyliron-Diene Photochemistry: The η⁴-s-transIsomer of the Classical Fe(CO)₃(η⁴-s-cis-1,3-butadiene) Discovered by Time-Resolved IR Spectroscopy and Theoretically Examined by Density Functional Methods

et al. 2003

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The photolysis of Fe(CO)3(η4-s-cis-1,3-butadiene) (1) and Fe(CO)4(η2-1,3-butadiene) (2), formerly studied in low-temperature matrixes, is reexamined in cyclohexane solution at ambient temperature using time-resolved IR spectroscopy in the ν(CO) region. Flash photolysis of 2 (λexc = 308 nm) generates Fe(CO)3(η4-s-trans-1,3-butadiene) (5) as a transient product, which then rearranges to form the classical η4-s-cis-1,3-butadiene complex 1. Species 5, previously addressed as the coordinately unsaturated Fe(CO)3(η2-1,3-butadiene) (3), is also photogenerated from 1, in this case along with the very short-lived CO loss fragment Fe(CO)2(η4-1,3-butadiene) (τ < 4 μs under CO atmosphere). It decays by temperature-dependent first-order kinetics (τ = 13 ms at 25 °C; ΔH ⧧ = 17.3 kcal·mol-1) with nearly complete recovery of 1. According to density functional calculations at the BP86 level of theory, 5 resides in a distinct energy minimum, 20.3 kcal·mol-1 above 1 and separated from it by a barrier of 15.0 kcal·mol-1. Its computed structure involves a diene dihedral angle of 129°. Species 3 (with a diene dihedral angle of −150.1°), by contrast, is predicted to exist in a rather flat minimum, which makes it too short-lived for detection with our instrumentation. Flash photolysis of Fe(CO)5 generates the very short-lived (<1 μs) doubly unsaturated Fe(CO)3(solv) species in addition to the familiar Fe(CO)4(solv) fragment (τ = 10−15 μs), Fe2(CO)9 being the ultimate product in the absence of potential trapping agents other than CO. Deliberate contamination of the system with water gives rise to the formation of Fe(CO)4(H2O) as a longer lived transient (ca. 1 ms). In the presence of 1,3-butadiene, both 2 and 5 appear almost instantaneously. The latter decays, again in the millisecond time range, with formation of 1, thus providing clear evidence of a single-photon route from Fe(CO)5 to 1 in addition to the established two-photon sequence via the monosubstituted complex 2.

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Ultraschnelle Elektronenkristallographie: Anbruch einer neuen Ära

Thomas

2004

Angewandte Chemie

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Mit Empfindlichkeiten im Submonoschichtbereich, räumlichen Auflösungen von 0.02 Å und Zeitauflösungen unterhalb von Pikosekunden können dank der neuesten Entwicklungen von Zewail und Mitarbeitern Strukturen auf festen Oberflächen aufgeklärt werden (siehe Bild). Den Weg zu dieser außergewöhnlich leistungsstarken Technik und ihre Abgrenzung zu anderen Verfahren der Strukturaufklärung schildert dieser Beitrag.

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Die Struktur von [Fe(CO)4] - ein neues Kapitel einer langen Geschichte

Cited by 8 publications

References 27 publications

Unexpected Direct Iron‐Fluorine Bonds in Trifluorophosphane Iron Complexes: An Alternative to Bridging Trifluorophosphane and Difluorophosphido Groups

Unexpected Direct Iron‐Fluorine Bonds in Trifluorophosphane Iron Complexes: An Alternative to Bridging Trifluorophosphane and Difluorophosphido Groups

A Novel Facet of Carbonyliron-Diene Photochemistry: The η⁴-s-transIsomer of the Classical Fe(CO)₃(η⁴-s-cis-1,3-butadiene) Discovered by Time-Resolved IR Spectroscopy and Theoretically Examined by Density Functional Methods

Ultraschnelle Elektronenkristallographie: Anbruch einer neuen Ära

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Die Struktur von [Fe(CO)4] - ein neues Kapitel einer langen Geschichte

Cited by 8 publications

References 27 publications

Unexpected Direct Iron‐Fluorine Bonds in Trifluorophosphane Iron Complexes: An Alternative to Bridging Trifluorophosphane and Difluorophosphido Groups

Unexpected Direct Iron‐Fluorine Bonds in Trifluorophosphane Iron Complexes: An Alternative to Bridging Trifluorophosphane and Difluorophosphido Groups

A Novel Facet of Carbonyliron-Diene Photochemistry: The η4-s-transIsomer of the Classical Fe(CO)3(η4-s-cis-1,3-butadiene) Discovered by Time-Resolved IR Spectroscopy and Theoretically Examined by Density Functional Methods

Ultraschnelle Elektronenkristallographie: Anbruch einer neuen Ära

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About

A Novel Facet of Carbonyliron-Diene Photochemistry: The η⁴-s-transIsomer of the Classical Fe(CO)₃(η⁴-s-cis-1,3-butadiene) Discovered by Time-Resolved IR Spectroscopy and Theoretically Examined by Density Functional Methods