Synthesis and Characterization of Ruthenium Bis(β-diketonato) Pyridine-Imidazole Complexes for Hydrogen Atom Transfer.
Saved in:
| Title: | Synthesis and Characterization of Ruthenium Bis(β-diketonato) Pyridine-Imidazole Complexes for Hydrogen Atom Transfer. |
|---|---|
| Authors: | Wu, Adam1, Masland, Josua1, Swartz, Rodney D.1, Kaminsky, Werner1, Mayer, James M.1 mayer@chem.washington.edu |
| Source: | Inorganic Chemistry. 12/24/2007, Vol. 46 Issue 26, p11190-11201. 12p. 2 Diagrams, 2 Charts, 2 Graphs. |
| Subjects: | Ruthenium, Pyridine, Imidazoles, Complex compounds, Hydrogen |
| Abstract: | Ruthenium bis(β-diketonato) complexes have been prepared at both the RuII and RuIII oxidation levels and with protonated and deprotonated pyridine-imidazole ligands. RuII(acac)2(py-imH) (1), [RuIII(acac)2(py-imH)]OTf (2), RuIII-(acac)2(py-im) (3), RuII(hfac)2(py-imH) (4), and [DBU-H][RuII(hfac)2(py-im)] (5) have been fully characterized, including X-ray crystal structures (acac = 2,4-pentanedionato, hfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionato, py-imH = 2-(2′-pyridyl)imidazole, DBU = 1,8-diazabicyclo[5.4.0]undec-7-ene). For the acac-imidazole complexes 1 and 2, cyclic voltammetry in MeCN shows the RuIII/II reduction potential (E1/2) to be -0.64 V versus Cp2Fe+/0. E1/2 for the deprotonated imidazolate complex 3 (-1.00 V) is 0.36 V more negative. The RuII bis-hfac analogues 4 and 5 show the same ΔE1/2 = 0.36 V but are 0.93 V harder to oxidize than the acac derivatives (0.29 and -0.07 V). The difference in acidity between the acac and hfac derivatives is much smaller, with pKa values of 22.1 and 19.3 in MeCN for 1 and 4, respectively. From the E1/2 and pKa values, the bond dissociation free energies (BDFEs) of the N-H bonds in 1 and 4 are calculated to be 62.0 and 79.6 kcal mol-1 in MeCN - a remarkable difference of 17.6 kcal mol-1 for such structurally similar compouflds. Consistent with these values, there is a facile net hydrogen atom transfer from 1 to TEMPO• (2,2,6,6-tetramethylpiperidine-1-oxyl radical) to give 3 and TEMPO-H. The ΔG° for this reaction is -4.5 kcal mol-1. 4 is not oxidized by TEMPO• (ΔG° = +13.1 kcal mol-1), but in the reverse direction TEMPO-H readily reduces in situ generated RuIII(hfac)2(py-im) (6). A RuII-imidazoline analogue of 1, RuII-(acac)2(py-imnH) (7), reacts with 3 equiv of TEMPO• to give the imidazo/ate 3 and TEMPO-H, with dehydrogenation of the imidazoline ring. [ABSTRACT FROM AUTHOR] |
| Copyright of Inorganic Chemistry is the property of American Chemical Society and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
| FullText | Text: Availability: 0 |
|---|---|
| Header | DbId: egs DbLabel: Engineering Source An: 28384421 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
| IllustrationInfo | |
| Items | – Name: Title Label: Title Group: Ti Data: Synthesis and Characterization of Ruthenium Bis(β-diketonato) Pyridine-Imidazole Complexes for Hydrogen Atom Transfer. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Wu%2C+Adam%22">Wu, Adam</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Masland%2C+Josua%22">Masland, Josua</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Swartz%2C+Rodney+D%2E%22">Swartz, Rodney D.</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Kaminsky%2C+Werner%22">Kaminsky, Werner</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Mayer%2C+James+M%2E%22">Mayer, James M.</searchLink><relatesTo>1</relatesTo><i> mayer@chem.washington.edu</i> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Inorganic+Chemistry%22">Inorganic Chemistry</searchLink>. 12/24/2007, Vol. 46 Issue 26, p11190-11201. 12p. 2 Diagrams, 2 Charts, 2 Graphs. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Ruthenium%22">Ruthenium</searchLink><br /><searchLink fieldCode="DE" term="%22Pyridine%22">Pyridine</searchLink><br /><searchLink fieldCode="DE" term="%22Imidazoles%22">Imidazoles</searchLink><br /><searchLink fieldCode="DE" term="%22Complex+compounds%22">Complex compounds</searchLink><br /><searchLink fieldCode="DE" term="%22Hydrogen%22">Hydrogen</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Ruthenium bis(β-diketonato) complexes have been prepared at both the RuII and RuIII oxidation levels and with protonated and deprotonated pyridine-imidazole ligands. RuII(acac)2(py-imH) (1), [RuIII(acac)2(py-imH)]OTf (2), RuIII-(acac)2(py-im) (3), RuII(hfac)2(py-imH) (4), and [DBU-H][RuII(hfac)2(py-im)] (5) have been fully characterized, including X-ray crystal structures (acac = 2,4-pentanedionato, hfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionato, py-imH = 2-(2′-pyridyl)imidazole, DBU = 1,8-diazabicyclo[5.4.0]undec-7-ene). For the acac-imidazole complexes 1 and 2, cyclic voltammetry in MeCN shows the RuIII/II reduction potential (E1/2) to be -0.64 V versus Cp2Fe+/0. E1/2 for the deprotonated imidazolate complex 3 (-1.00 V) is 0.36 V more negative. The RuII bis-hfac analogues 4 and 5 show the same ΔE1/2 = 0.36 V but are 0.93 V harder to oxidize than the acac derivatives (0.29 and -0.07 V). The difference in acidity between the acac and hfac derivatives is much smaller, with pKa values of 22.1 and 19.3 in MeCN for 1 and 4, respectively. From the E1/2 and pKa values, the bond dissociation free energies (BDFEs) of the N-H bonds in 1 and 4 are calculated to be 62.0 and 79.6 kcal mol-1 in MeCN - a remarkable difference of 17.6 kcal mol-1 for such structurally similar compouflds. Consistent with these values, there is a facile net hydrogen atom transfer from 1 to TEMPO• (2,2,6,6-tetramethylpiperidine-1-oxyl radical) to give 3 and TEMPO-H. The ΔG° for this reaction is -4.5 kcal mol-1. 4 is not oxidized by TEMPO• (ΔG° = +13.1 kcal mol-1), but in the reverse direction TEMPO-H readily reduces in situ generated RuIII(hfac)2(py-im) (6). A RuII-imidazoline analogue of 1, RuII-(acac)2(py-imnH) (7), reacts with 3 equiv of TEMPO• to give the imidazo/ate 3 and TEMPO-H, with dehydrogenation of the imidazoline ring. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Inorganic Chemistry is the property of American Chemical Society and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
| PLink | https://search.ebscohost.com/login.aspx?direct=true&site=eds-live&db=egs&AN=28384421 |
| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1021/ic7015726 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 12 StartPage: 11190 Subjects: – SubjectFull: Ruthenium Type: general – SubjectFull: Pyridine Type: general – SubjectFull: Imidazoles Type: general – SubjectFull: Complex compounds Type: general – SubjectFull: Hydrogen Type: general Titles: – TitleFull: Synthesis and Characterization of Ruthenium Bis(β-diketonato) Pyridine-Imidazole Complexes for Hydrogen Atom Transfer. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Wu, Adam – PersonEntity: Name: NameFull: Masland, Josua – PersonEntity: Name: NameFull: Swartz, Rodney D. – PersonEntity: Name: NameFull: Kaminsky, Werner – PersonEntity: Name: NameFull: Mayer, James M. IsPartOfRelationships: – BibEntity: Dates: – D: 24 M: 12 Text: 12/24/2007 Type: published Y: 2007 Identifiers: – Type: issn-print Value: 00201669 Numbering: – Type: volume Value: 46 – Type: issue Value: 26 Titles: – TitleFull: Inorganic Chemistry Type: main |
| ResultId | 1 |
