Kristall‐ und Molekülstruktur eines Tetracarbonyl‐(carben)‐eisen‐Komplexes

Hüttner, Gottfried; Gartzke, Wolfgang

doi:10.1002/cber.19721050831

Cited by 75 publications

(26 citation statements)

References 12 publications

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“…The Fe±CH 2 bond length of equatorial carbene iron tetracarbonyl 11 b is calculated to be 1.826 A Ê and significantly shorter than the experimental values ranging from 2.001±2.010 A Ê reported for hetero substituted, electron-rich carbene iron tetracarbonyl complexes [60]. We note, however, that our calculated iron-car-bene bond length is still substantially larger than the experimental iron-carbene bond of 1.734(6) A Ê reported for [(CO) 3 PPh 3 FeC(Ni±Pr 2 )] + [61].…”

Section: Fe(co) 4 Ch 2 and Fe(co) 4 Cfcontrasting

confidence: 57%

Ligand Site Preference in Iron Tetracarbonyl Complexes Fe(CO) ₄ L (L = CO, CS, N ₂ , NO ⁺ , CN ^– , NC ^– , η ² ‐C ₂ H ₄ , η ² ‐C ₂ H ₂

Chen

Hartmann

Frenking

2001

Z. anorg. allg. Chem.

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Equilibrium geometries, bond dissociation energies and relative energies of axial and equatorial iron tetracarbonyl complexes of the general type Fe(CO) 4 L (L = CO, CS, N2, NO + , CN ± , NC ± , g 2 -C 2 H 4 , g 2 -C 2 H 2 , CCH 2 , CH 2 , CF 2 , NH 3 , NF 3 , PH 3 , PF 3 , g 2 -H 2 ) are calculated in order to investigate whether or not the ligand site preference of these ligands correlates with the ratio of their r-donor/p-acceptor capabilities. Using density functional theory and effectivecore potentials with a valence basis set of DZP quality for iron and a 6-31G(d) all-electron basis set for the other elements gives theoretically predicted structural parameters that are in very good agreement with previous results and available experimental data. Improved estimates for the (CO) 4 Fe±L bond dissociation energies (D 0 ) are obtained using the CCSD(T)/II//B3LYP/II combination of theoretical methods. The strongest Fe±L bonds are found for complexes involving NO + , CN ± , CH 2 and CCH 2 with bond dissociation energies of 105.1, 96.5, 87.4 and 83.8 kcal mol ±1 , respectively. These values decrease to 78.6, 64.3 and 64.2 kcal mol ±1 , respectively, for NC ± , CF 2 and CS. The Fe(CO) 4 L complexes with L = CO, g 2 -C 2 H 4 , g 2 -C 2 H 2 , NH 3 , PH 3 and PF 3 have even smaller bond dissociation energies ranging from 45.2 to 37.3 kcal mol ±1 . Finally, the smallest bond dissociation energies of 23.5, 22.9 and 18.5 kcal mol ±1 , respectively are found for the ligands NF 3 , N 2 and g 2 -H 2 . A detailed examination of the (CO) 4 Fe±L bond in terms of a semi-quantitative Dewar-Chatt-Duncanson (DCD) model is presented on the basis of the CDA and NBO approach. The comparison of the relative energies between axial and equatorial isomers of the various Fe(CO) 4 L complexes with the r-donor/p-acceptor ratio of their respective ligands L thus does not generally support the classical picture of p-accepting ligands preferring equatorial coordination sites and r-donors tending to coordinate in axial positions. In particular, this is shown by iron tetracarbonyl complexes with L = g 2 -C 2 H 2 , g 2 -C 2 H 4 , g 2 -H 2 . Although these ligands are predicted by the CDA to be stronger r-donors than p-acceptors, the equatorial isomers of these complexes are more stable than their axial pendants.

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Section: Fe(co) 4 Ch 2 and Fe(co) 4 Cfcontrasting

confidence: 57%

Ligand Site Preference in Iron Tetracarbonyl Complexes Fe(CO) ₄ L (L = CO, CS, N ₂ , NO ⁺ , CN ^– , NC ^– , η ² ‐C ₂ H ₄ , η ² ‐C ₂ H ₂

Chen

Hartmann

Frenking

2001

Z. anorg. allg. Chem.

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“…The solid melts at 75-808C and discolours at 140-1558C; however, no gas evolution is observed at these temperatures in the solid state and no decomposition is observed by variable-temperature NMR spectroscopy in [D6]DMSO. This result stands in contrast to the cases of the 1,4-dimethyltetrazolium hydridoferrate [13] and 1,3-dimethylimidazolium hydridoferrate, [14] both of which decompose with the elimination of dihydrogen to form the corresponding [azolylidene]irontetracarbonyl complexes.…”

Section: Transition Metal Electrophiles For Lewis Pairscontrasting

confidence: 56%

“…Hydrogen Activation using 1-Adamantylborane Á THF Following the General Method above, carbene 1 (0.087 g, 0.49 mmol) in hexane (4 mL) was added to 1-adamantylborane Á THF (14) [8a,b] (0.100 g, 0.485 mmol) in hexane (4 mL) under pressure of hydrogen. Proton NMR confirms the formation of aminal 8 as described below with decomposition of borane.…”

Section: General Methods For Carbene Dihydrogen Activationmentioning

confidence: 99%

“…Alkylboranes are not as highly electrophilic as the fluoroaryl boranes mentioned above; however, 1-boraadamantane Á THF (14) was of interest owing to the unusual electrophilicity of the borane centre that results in the geometric constraints in the system. The boron atom is fixed in a trigonal pyramidal geometry due to the fused adamantane ring system.…”

Section: Boron Electrophiles For Lewis Pairsmentioning

confidence: 99%

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Carbene-Based Lewis Pairs for Hydrogen Activation

et al. 2011

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A series of Lewis acid-base pairs containing sterically demanding carbenes were investigated for hydrogen activation that could potentially be reversible for use in hydrogen storage applications. When electron-rich boranes are employed as electrophiles, the imidazolium cation is reduced to a 2H-imidazoline (aminal). The aminals were synthesized independently by reduction of imidazolium cations with strong reducing agents. Carbocations were also found to act as electrophiles for hydrogen activation. Preliminary results revealed that it is possible to reduce an alcohol to an alkane using hydrogen gas as a reducing agent in these systems. Finally, it was demonstrated that a transition metal can be used as an electrophile to activate hydrogen through heterolytic cleavage. 1 3 4 2 Scheme 1. A carbene-borane Lewis pair for hydrogen activation.

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“…Though first examples have been described already in the 1970s [17,18], NHC complexes of iron are still relatively scarce. They have received increasing attention only in recent years [19], spurred by possible uses in catalysis [20,21], bioinspired chemistry [22,23] and for the stabilization of unusual iron oxidation states [24 -26].…”

Section: Introductionmentioning

confidence: 99%

Nickel(II) and Iron(II) Complexes with Tetradentate NHC/Amide Hybrid Ligands

Klawitter

Meyer

Demeshko

et al. 2013

Zeitschrift Für Naturforschung B

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Kristall‐ und Molekülstruktur eines Tetracarbonyl‐(carben)‐eisen‐Komplexes

Cited by 75 publications

References 12 publications

Ligand Site Preference in Iron Tetracarbonyl Complexes Fe(CO) ₄ L (L = CO, CS, N ₂ , NO ⁺ , CN ^– , NC ^– , η ² ‐C ₂ H ₄ , η ² ‐C ₂ H ₂

Ligand Site Preference in Iron Tetracarbonyl Complexes Fe(CO) ₄ L (L = CO, CS, N ₂ , NO ⁺ , CN ^– , NC ^– , η ² ‐C ₂ H ₄ , η ² ‐C ₂ H ₂

Carbene-Based Lewis Pairs for Hydrogen Activation

Nickel(II) and Iron(II) Complexes with Tetradentate NHC/Amide Hybrid Ligands

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Kristall‐ und Molekülstruktur eines Tetracarbonyl‐(carben)‐eisen‐Komplexes

Cited by 75 publications

References 12 publications

Ligand Site Preference in Iron Tetracarbonyl Complexes Fe(CO) 4 L (L = CO, CS, N 2 , NO + , CN – , NC – , η 2 ‐C 2 H 4 , η 2 ‐C 2 H 2

Ligand Site Preference in Iron Tetracarbonyl Complexes Fe(CO) 4 L (L = CO, CS, N 2 , NO + , CN – , NC – , η 2 ‐C 2 H 4 , η 2 ‐C 2 H 2

Carbene-Based Lewis Pairs for Hydrogen Activation

Nickel(II) and Iron(II) Complexes with Tetradentate NHC/Amide Hybrid Ligands

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Ligand Site Preference in Iron Tetracarbonyl Complexes Fe(CO) ₄ L (L = CO, CS, N ₂ , NO ⁺ , CN ^– , NC ^– , η ² ‐C ₂ H ₄ , η ² ‐C ₂ H ₂

Ligand Site Preference in Iron Tetracarbonyl Complexes Fe(CO) ₄ L (L = CO, CS, N ₂ , NO ⁺ , CN ^– , NC ^– , η ² ‐C ₂ H ₄ , η ² ‐C ₂ H ₂