Brunner, Henri and Kurosawa, Takaki and Muschiol, Manfred and Tsuno, Takashi and Balazs, Gabor and Bodensteiner, Michael (2013) Tuning the Dissociation of the Fe-PPh2(OR) Bond in Chiral-at-Metal Complexes [CpFe(Prophos)PPh2(OR)]PF6 (R = Me, Et, iPr, tBu). The Preparative Trick of N-2 Bubbling. ORGANOMETALLICS, 32 (17). pp. 4904-4911. ISSN 0276-7333, 1520-6041
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The compounds (R-Fe,R-C)-/(S-Fe,R-C)-[CpFe-(Prophos)PPh(OMe)(2)]PF6 and (R-Fe,R-C)-/(S-Fe,R-C)-[CpFe-(Prophos)PPh2(OR)]PF6 (R = Me, Et, iPr, tBu) were synthesized, starting from (R-Fe,R-C)-/(S-Fe,R-C)-[CpFe(Prophos)NCMe]PF6, and characterized, including X-ray analyses. Bubbling a stream of N-2 through the solution speeded up the slow substitution reactions by removing the acetonitrile formed in the rate-determining cleavage of the Fe NCMe bond. Due to their acceptor ligands P(OMe)(3) and PPh(OMe)(2) the complexes [CpFe(Prophos)P(OMe)(3)]PF6 and [CpFe(Prophos)PPh(OMe)(2)]PF6 are configurationally stable at the metal atom. In contrast, [CpFe(Prophos)PPh3]PF6 does not form, due to the large cone angle of the ligand PPh3. Ideally, the electronic and steric effects of the ligands PPh2(OR) (R = Me, Et, iPr, tBu) are such that they tend to dissociate from the congested complexes (R-Fe,R-C)- and (S-Fe,R-C)-[CpFe(Prophos)PPh2(OR))]PF6. In the series (R-Fe,R-C)- and (S-Fe,R-C)-[CpFe(Prophos)PPh2(OR)]PF6, (R = Me, Et, iPr, tBu) electron donation and the cone angle of the ligands increase. Thus, the rates of the ligand exchange with P(OMe)(3) increased, initiated by the slow dissociation of the Fe-PPh2(OR) bond. For the R-Fe,R-C/S-Fe,R-C diastereomers of [CpFe(Prophos)PPh2(OR)]PF6 the half-lives of the first-order reactions were 125/350 h (R = Me), 75/275 h (R = Et), and 12/34 h (R = iPr) in CDCl3 at 60 degrees C.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | CRYSTAL-STRUCTURES; BOUND LIGANDS; DINITROGEN; STABILIZATION; REFINEMENT; PHOSPHORUS; PRODUCTS; EXCHANGE; SALTS; ACIDS; |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Anorganische Chemie > Alumni or Retired Professors > Prof. Dr. Henri Brunner |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 31 Mar 2020 13:05 |
| Last Modified: | 31 Mar 2020 13:05 |
| URI: | https://pred.uni-regensburg.de/id/eprint/16036 |
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