Closed, half open, and open ferrocenes: redox behavior and electron spin resonance of the radical cations

Elschenbroich, Christoph; Bilger, Edgar; Ernst, Richard D.; Wilson, David R.; Kralik, Michael S.

doi:10.1021/om00130a029

Cited by 63 publications

(37 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[ 15] For the present cases, the species 2c ·+ . These values point to a situation where the unpaired electron is delocalised over the molecule with substantial spin density on the ferrocene as well as the carbene part.…”

Section: ·+mentioning

confidence: 97%

Six‐Membered N‐Heterocyclic Carbenes with a 1,1′‐Ferrocenediyl Backbone: Bulky Ligands with Strong Electron‐Donor Capacity and Unusual Non‐Innocent Character

et al. 2009

View full text Add to dashboard Cite

The chemistry of N-heterocyclic carbenes (NHCs) [1] has developed rapidly since Arduengo et al. described the first stable crystalline NHC, 1,3-di-1-adamantylimidazolin-2-ylidene (IAd), [2] in 1991. Based on pioneering work by the groups of Herrmann and Enders, [3] they are widely applied as ligands in transition metal-catalysed reactions.[1c,1e] Their steric and electronic properties can be modified by the exocyclic substituents at the nitrogen atoms as well as by the backbone which connects the two nitrogen atoms. While five-membered NHCs based on imidazol, imidazolin and 1,2,4-triazol have received most attention so far, there is great current interest in "non-standard" NHCs, i.e. those with ring sizes other than five and/or with heteroatoms in the backbone.[4] With a view to redox-tunable catalysts, [5] we have focused our efforts on [3]ferrocenophane-type NHCs, where formally a d-block metal atom constitutes an integral part of a six-membered ring (Figure 1). Figure 1. Structures of the ferrocene-based N-heterocyclic carbenes 2 and their formamidinium precursors 1. 2 is drawn in a way that highlights the six-membered ring structure.Independently from us, Bielawski and co-workers have also been addressing this system. They recently communicated the first two examples of such NHCs, generated in situ by deprotonation of the corresponding formamidinium tetrafluoroborates 1 (Figure 1).[6] 2a (R = iBu) and 2b (R = Ph) proved to be too unstable for isolation, and only 2a was sufficiently stable for NMR spectroscopic characterisation in solution. However, both could be trapped by coordination to [RhCl(L) 2 ] fragments. Electrochemical data proved to be in support of an electronic communication between the two metal centres in these Rh complexes, and throughspace π-backbonding between the Fe atom and the carbene C atom was invoked to be responsible for this.By utilising bulkier substituents, we have been able to synthesise stable, isolable NHCs of this kind. This gives us the opportunity for a detailed investigation of the redox

show abstract

Section: ·+mentioning

confidence: 97%

Six‐Membered N‐Heterocyclic Carbenes with a 1,1′‐Ferrocenediyl Backbone: Bulky Ligands with Strong Electron‐Donor Capacity and Unusual Non‐Innocent Character

et al. 2009

View full text Add to dashboard Cite

show abstract

“…There are significant differences in the redox properties of the ''closed'' Fe(g 5 -cyclopentadienyl) 2 , ''half-open'' (g 5 -cyclopentadienyl)Fe(g 5 -2,4-dimethyl-pentadienyl) and ''open'' Fe(g 5 -2,4-dimethyl-pentadienyl) 2 . The chemical lability of the corresponding Fe III complexes is increasing following the sequence: closed > half-open > open [3].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical oxidation of Cp*Ru(η5-2,4-dimethyl-pentadienyl) in acetonitrile. One-electron vs. two-electron generation of cationic acetonitrile coordinated complexes

Cházaro-Ruiz

González

Paz-Sandoval

2005

Journal of Electroanalytical Chemistry

View full text Add to dashboard Cite

“…This study shows that there are significant differences in the redox properties of the ''closed'' Fe(g 5 -cyclopentadienyl) 2 , ''half-open'' (g 5 -cyclopentadienyl)Fe(2,4-dimethyl-g 5 -pentadienyl) and ''open'' Fe(2,4-dimethyl-g 5 -pentadienyl) 2 . The chemical lability of the corresponding Fe III compounds increases following the sequence: closed < half-open < open [9].…”

Section: -C 4 H 3 O) (3) (Scheme 1)mentioning

confidence: 99%

Electrochemical oxidation of half-open ruthenocene compounds. Role of acyclic ligands on acetonitrile coordination

Cházaro-Ruiz

Maisonhaute

Thouin

et al. 2007

Journal of Electroanalytical Chemistry

View full text Add to dashboard Cite

Closed, half open, and open ferrocenes: redox behavior and electron spin resonance of the radical cations

Abstract: Successive opening of one or both rings of ferrocene results in a cathodic shift of the redox potential for the couple ferrocene/ferricinium, increased chemical lability, and vastly decreased g anisotropy in the ESR

Cited by 63 publications

References 3 publications

Six‐Membered N‐Heterocyclic Carbenes with a 1,1′‐Ferrocenediyl Backbone: Bulky Ligands with Strong Electron‐Donor Capacity and Unusual Non‐Innocent Character

Six‐Membered N‐Heterocyclic Carbenes with a 1,1′‐Ferrocenediyl Backbone: Bulky Ligands with Strong Electron‐Donor Capacity and Unusual Non‐Innocent Character

Electrochemical oxidation of Cp*Ru(η5-2,4-dimethyl-pentadienyl) in acetonitrile. One-electron vs. two-electron generation of cationic acetonitrile coordinated complexes

Electrochemical oxidation of half-open ruthenocene compounds. Role of acyclic ligands on acetonitrile coordination

Contact Info

Product

Resources

About