Molecular Electrochemistry of Cyclophanes

Speiser, Bernd

doi:10.1002/3527603964.ch14

Cited by 5 publications

(2 citation statements)

References 97 publications

(143 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[76] The redox potentials of Grubbs II complexes with saturated and unsaturated NHC (but identical 4-R groups) are very similar (with the exception of 4-R = NEt 2 ); indicative of similar donor properties in the two classes of ligands. [77] However, the catalytic properties of the two series of complexes are quite different (see section on Catalysis).…”

Section: Electrochemical Studiesmentioning

confidence: 99%

π‐Face Donor Properties of N‐Heterocyclic Carbenes in Grubbs II Complexes

Leuthäußer

Schmidts

Thiele

et al. 2008

Chemistry A European J

138

View full text Add to dashboard Cite

The electron-donating properties of eighteen N-heterocyclic carbenes (N,N'-bis(2,6-dimethylphenyl)imidazol)-2-ylidene and the respective dihydro ligands) with 4,4'-R substituted aryl rings (4,4'-R = NEt2, OMe, Me, H, SMe, F, Cl, Br, I) in the respective Grubbs II complexes were studied using electrochemical techniques. The nature of the 4-R substituent has a strong influence on the RuII/III redox potentials ranging between DeltaE1/2= +0.196 and +0.532 V. Three unsymmetrical Grubbs II complexes with 4-R not equal to 4-R' were also synthesized. Dynamic NMR spectroscopy revealed the restricted rotation around the (NHC)C-Ru bond (DeltaG = 89 kJ mol(-1) at 333 K) resulting in two atropisomers, respectively, with an isomer ratio close to unity. Each of the isomers, that is the two orientations of the 4-R/4-R' substituted mesityl ring with respect to the R=CHPh unit, gives rise to different redox potentials (4-R = NEt2, 4-R' = Br: DeltaE1/2= +0.232 and +0.451 V). In the oxidized Grubbs II complex (4-R = NEt2, H) and in the cathodic isomer the electron rich aryl ring is located above the Ru=CHPh unit. This orientational effect provides clear evidence for strong pi-pi through-space interactions in the RuIII complexes, assuming that the alternative through-bond transfer of electron density is equally efficient in both isomers.

show abstract

Section: Electrochemical Studiesmentioning

confidence: 99%

π‐Face Donor Properties of N‐Heterocyclic Carbenes in Grubbs II Complexes

Leuthäußer

Schmidts

Thiele

et al. 2008

Chemistry A European J

138

View full text Add to dashboard Cite

show abstract

“…Cyclic voltammetry (CV) is suitable to study the effects of intramolecular redox processes. Several studies on cyclophanes revealed that those molecules that were substituted by thiophenes or that incorporated thiophene or tetrathiafulvalene (TTF) rings into the cyclophane scaffold or that were complexed by metal fragments show reversible oxidation processes . Therefore, we also expected for our mixed superphanes useful results in terms of reversible redox processes.…”

Section: Resultsmentioning

confidence: 85%

Transannular Interactions in Mixed Superphanes with One Thiophene and One CpCo-Stabilized Cyclobutadiene Ring: Syntheses, Structures, and Electrochemistry

et al. 2007

View full text Add to dashboard Cite

Superphanes consisting of one thiophene ring and various substituted RCo-stabilized cyclobutadiene (CBD) rings (R = Cp, C5H4(CH3), C5(CH3)5, C5H4(Si(CH3)3), C5H4(COCH3), 8−12) and one superphane with one thiophene ring and one CpCo-stabilized cyclopentadienone ring (13) were synthesized. The starting point was a tricyclic diyne with a central thiophene ring and two condensed 4-cyclodecynes, 19. Heating of 19 with RCo(COD) yielded 8−12, whereas the heating of 19 with CpCo(CO)2 gave 13. X-ray structural investigation of 8−13 afforded the geometrical parameters in the solid state. Cyclic voltammetry showed a strong interaction between the thiophene ring and the CpCo-stabilized cyclobutadiene part. This interaction was substantiated by comparison between the CV data of 8−12 and model systems containing only the CpCo(CBD) part.

show abstract