Recent applications of tricarbonyliron-diene complexes to organic synthesis

Knölker, Hans‐Joachim; Braier, Arnold; Bröcher, Dirk J.; Cämmerer, Simon; Fröhner, Wolfgang; Gonser, Peter; Hermann, H; Herzberg, Daniela; Reddy, Kethiri R.; Rohde, Guy

doi:10.1351/pac200173071075

Cited by 50 publications

(29 citation statements)

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“…13,14 In the gas phase, UVirradiation of Fe(CO) 5 leads to the dissociation of two CO ligands to form 3 Fe(CO) 3 . 9,11,[18][19][20] It is hypothesized that 3 Fe(CO) 3 coordinates a single 1-pentene molecule via a spin-allowed process to form Recently, Glascoe et al performed a similar experiment on a picosecond time-scale and found that after 266-nm excitation of A a single CO is dissociated to form B 1 within a few ps.…”

Section: 14mentioning

confidence: 99%

“…1 Photoactivated Fe(CO) 5 , which is used to catalyze alkene isomerization, is a particularly efficient catalyst, and as a result, it has been used by synthetic chemists for decades. [1][2][3][4][5][6][7] Numerous mechanistic studies have resolved the key intermediates in the isomerization reaction under a variety of conditions (gas-and solution-phase and low temperature matrices), 3,4,6-17 yet many questions remain about the mechanism in room-temperature solution, particularly concerning the role of high spin…”

Section: Introductionmentioning

confidence: 99%

“…Many authors have proposed that the efficiency of the reaction is linked to the high spin state of B 1 since the turnover rate for the reaction catalyzed with photoactivated Ru(CO) 5 , a complex with only singlet transient species in the catalytic cycle, is much less efficient. 8,11,16,17,19,22 However, this work indicates that the triplet form of B 1 does not play a significant role in the isomerization reaction since it reacts to form a singlet form of B 1 on a subpicosecond time-scale.…”

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Mechanism for Iron-Catalyzed Alkene Isomerization in Solution

et al. 2008

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ABSTRACT.Here we report nano-through microsecond time-resolved IR experiments of iron-catalyzed alkene isomerization in room-temperature solution. We have monitored the photochemistry of a model system, Fe(CO) 4 (η 2 -1-hexene), in neat 1-hexene solution. UV-photolysis of the starting material leads to the dissociation of a single CO to form Fe(CO) 3 (η 2 -1-hexene), in a singlet spin state. This CO loss complex shows a dramatic selectivity to form an allyl hydride, HFe(CO) 3 (η 3 -C 6 H 11 ), via an internal C-H bondcleavage reaction in 5-25 ns. We find no evidence for the coordination of an alkene molecule from the bath to the CO loss complex, but do observe coordination to the allyl hydride, indicating that it is the key intermediate in the isomerization mechanism. Coordination of the alkene ligand to the allyl hydride leads to the formation of the bis-alkene isomers, Fe(CO) 3 (η 2 -1-hexene)(η 2 -2-hexene) and Fe(CO) 3 (η 2 -1-hexene) 2 . Because of the thermodynamic stability of Fe(CO) 3 (η 2 -1-hexene)(η 2 -2-hexene) over Fe(CO) 3 (η 2 -1-hexene) 2 (ca. 12 kcal/mol), nearly 100% of the alkene population will be 2-alkene. The results presented herein provide the first direct evidence for this mechanism in solution and suggest modifications to the currently accepted mechanism.

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Section: 14mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mechanism for Iron-Catalyzed Alkene Isomerization in Solution

et al. 2008

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“…241, 242 Theoretical analyses 243,244 have tended to consider the rearrangement in terms of rotation of the Fe(CO) 2 L fragment relative to the diene. A number of (η 4 -enone)Fe(CO) 2 L complexes have also been investigated.…”

Section: -Cyclopentadienyl and Similar Ligandsmentioning

confidence: 99%

Stereochemical Nonrigidity of Organometallic Complexes

Faller¹

2005

Encyclopedia of Inorganic Chemistry

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Compounds that undergo intramolecular rearrangements at rates that affect the NMR line shapes in generally accessible temperature ranges are described as stereochemically nonrigid. Analysis of 1D and 2D NMR spectra as a function of temperature often allow the rates, as well as the mechanisms of interconversion of conformers or isomers, to be determined. Examples were selected to illustrate the importance of stereochemical nonrigidity in reactivity and the potential for affecting stereochemistry in the products of reactions.

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“…Many applications of the M(CO) 5 (MPC) systems involve photo-induced CO loss which generates a key tricarbonyl intermediate, Fe(CO) 3 . For example, the photolytic generation of Fe(CO) 3 from Fe(CO) 5 has been shown to be a key step in catalyzing alkene isomerizations [6].…”

Section: Introductionmentioning

confidence: 99%