A Correlation of Electrochemical Oxidation and Ionization Potentials of Group 4B Dimetals

Mochida, Kunio; Itani, Atsuko; Yokoyama, M; Worley, S. D.; Kochi, Jay K.

doi:10.1246/bcsj.58.2149

Cited by 31 publications

(8 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The origin of the anodic peak at E p ≈ 0.3 V, present in all voltammograms ( Figures 1 -3 Okano and Mochida, 1991) and of hexaalkyldigermanes (1.7 and 1.48 V vs. SCE for Me and Et, respectively; Mochida et al, 1985) is all too high. Another system which might account for this peak is the oxidation of Ph 3 GeH formed either via H-atom abstraction by radical Ph 3 Ge ‧ or by protonation of Ph 3 Ge -(although this last possibility must certainly be ruled out because the second reduction step is reversible for all complexes; cf.…”

Section: Cyclic Voltammetrymentioning

confidence: 85%

Complexes of germanium chlorides (RnGeCl4-n, n=0-3; R=Me, Ph) with redox active N-heteroaromatic ligands: an electrochemical study

Dieng

Gningue-Sall

Jouikov

2012

Main Group Metal Chemistry

View full text Add to dashboard Cite

Methyl and phenyl germanium chlorides (R n GeCl 4-n , n = 1, 2, 3), just like GeCl 4 , form complexes with electroactive bidentate (2,2 ′ -bipyridine) and monodentate (imidazole, pyrimidine and 2,6-dichloro-pyridine) ligands, R n GeCl 4-n ‧ L x (x = 1 or 2 for bi-and monodentate Ls, respectively), which were studied by cyclic voltammetry and electron paramagnetic resonance (EPR) spectroscopy supported by density functional theory (DFT) calculations. Dative interactions of lone pair of N of these heteroaromatic ligands towards Ge lower the reduction potential E p of such complexes by about 1 V compared to own reduction potential E o of L. Electron transfer to these complexes is reversible, resulting in corresponding anion radicals. Elimination of Cl -anion from these species leads to L-coordinated radicals whose one-electron reduction is also reversible. Real-time, time-dependent EPR spectroelectrochemistry of electrogenerated anion radicals of complexes with 2,2 ′ -bipyridine (bipy) has shown that spin in these species is delocalized on the bipy moiety; nitrogen hfc constants suggest that two N atoms are non-equivalent and occupy different positions in the Ge environment. These findings are supported by DFT calculations.

show abstract

Section: Cyclic Voltammetrymentioning

confidence: 85%

Complexes of germanium chlorides (RnGeCl4-n, n=0-3; R=Me, Ph) with redox active N-heteroaromatic ligands: an electrochemical study

Dieng

Gningue-Sall

Jouikov

2012

Main Group Metal Chemistry

View full text Add to dashboard Cite

show abstract

“…For steric reasons (repulsion of N-Me and Si-SiMe 3 groups), the N lone pairs of 8 and 9 ( Figure 2 and 4) are practically orthogonal to the Si-N axes so they cannot participate in N→Si dative interaction and form complex 3c-4e internal systems. The HOMO in these cases is mostly formed with n(p z ) electrons of N. Consequently, in oxidative ET, 8 and 9 behave as trialkylamines [ 35 , 42 ] since the ionization potential of CH 3 N(CH 2 -) 2 unit is lower than that of polysilane chains (for oxidation of polysilanes see [ 43 , 44 , 45 , 46 ]). Their two step oxidation—first electron withdrawal from silocane N atom, while second being the oxidation of the oligosilanyl substituent—is thus akin to the oxidation scheme reported for Fc-substituted polysilanes [ 47 ].…”

Section: Resultsmentioning

confidence: 99%

“…In 5 , there are several potential sites of ET: the tetrasilane chain (oligosilanes are oxidizable at E p ≅ 1.3–1.7 V vs. SCE) [ 43 , 44 , 45 , 46 , 50 , 51 , 52 ] and two silatranyl units. Note that a donor effect of the latter might lower the oxidation potential of the connecting Si 4 bridge [ 53 ].…”

Section: Resultsmentioning

confidence: 99%

Oligosilanylated Silocanes

et al. 2021

View full text Add to dashboard Cite

A number of mono- and dioligosilanylated silocanes were prepared. Compounds included silocanes with 1-methyl-1-tris(trimethylsilyl)silyl, 1,1-bis[tris(trimethylsilyl)silyl], and 1,1-bis[tris(trimethylsilyl)germyl] substitution pattern as well as two examples where the silocane silicon atom is part of a cyclosilane or oxacyclosilane ring. The mono-tris(trimethylsilyl)silylated compound could be converted to the respective silocanylbis(trimethylsilyl)silanides by reaction with KOtBu and in similar reactions the cyclosilanes were transformed to oligosilane-1,3-diides. However, the reaction of the 1,1-bis[tris(trimethylsilyl)silylated] silocane with two equivalents of KOtBu leads to the replacement of one tris(trimethylsilyl)silyl unit with a tert-butoxy substituent followed by silanide formation via KOtBu attack at one of the SiMe3 units of remaining tris(trimethylsilyl)silyl group. For none of the silylated silocanes, signs of hypercoordinative interaction between the nitrogen and silicon silocane atoms were detected either in the solid state. by single crystal XRD analysis, nor in solution by 29Si-NMR spectroscopy. This was further confirmed by cyclic voltammetry and a DFT study, which demonstrated that the N-Si distance in silocanes is not only dependent on the energy of a potential N-Si interaction, but also on steric factors and through-space interactions of the neighboring groups at Si and N, imposing the orientation of the pz(N) orbital relative to the N-Si-X axis.

show abstract

“…First, we prepared disilanes having pyridyl groups in appropriate positions and measured their oxidation potentials [24,25]. The oxidation potential of 2-pyridylethyl substituted disilane 1b was slightly less positive than hexamethyldisilane 1a .…”

Section: Resultsmentioning

confidence: 99%

Generation of pyridyl coordinated organosilicon cation pool by oxidative Si-Si bond dissociation

Nokami¹,

Soma²,

Yamamoto³

et al. 2007

Beilstein J. Org. Chem.

View full text Add to dashboard Cite

An organosilicon cation stabilized by intramolecular pyridyl coordination was effectively generated and accumulated by oxidative Si-Si bond dissociation of the corresponding disilane using low temperature electrolysis, and was characterized by NMR and CSI-MS.Page 1 of (page number not for citation purposes) FindingsWe have recently developed the "cation pool" method, which involves the irreversible oxidative generation and accumulation of highly reactive cations in the absence of nucleophiles [1][2][3][4][5]. Heteroatom-stabilized carbocations, such as N-acyliminium ion pools and alkoxycarbenium ion pools have been generated based on oxidative C-H, C-Si, and C-S bond dissociation. Very recently, the oxidative C-C bond dissociation has been found to be effective for generation of a pool of a carbocation having a stabilizing group as shown in Scheme 1 [6].We have been interested in generation and accumulation of cations of other elements such as silicon using the "cation pool" method. Organosilicon cations are known to be extremely unstable and difficult to accumulate in solution [7][8][9][10][11]. Organo- Symmetrical disilanes having coordinating groups on both silicon atoms were used as starting materials for electrochemical generation and accumulation of organosilicon cations, because oxidative dissociation of the Si-Si bond leads to the formation of two equivalents of organosilicon cations and no other product is formed.In our earlier study, it was found that the introduction of a coordinating group such as a pyridyl group decreased the oxidation potential of tetraalkylstannanes, although there is no indication of the coordination in the neutral molecule. Dynamic intramolecular coordination to tin seems to facilitate electron transfer [22]. The coordination also stabilizes the thus-generated radical cation and weakens the C-Sn bond. A similar effect of intramolecular coordination was observed in the case of silicon [23]. Another important point is that pyridyl group is rather inactive toward the anodic oxidation. Thus, we chose to use a pyridyl group as a donor ligand.First, we prepared disilanes having pyridyl groups in appropriate positions and measured their oxidation potentials [24,25]. The oxidation potential of 2-pyridylethyl substituted disilane 1b was slightly less positive than hexamethyldisilane 1a. On the other hand, the oxidation potential of 2-pyridylphenyl substituted disilane 1d was much less positive than the corresponding disilane 1c having phenyl groups (Figure 1). 29 Si NMR chemical shifts of 1b and 1d were similar to those of 1a and 1c, indicating that no coordination of the pyridyl groups on silicon existed in the neutral molecules (Supporting Information File 1). Therefore, the significant effect of the 2-pyridyl group on the oxidation potential may be ascribed to effective intramolecular coordination to stabilize the radical cation intermediate. The conformationally less flexible 2-pyridylphenyl group seems to be more effective than the 2-pyridylethyl group.The intramolecular co...

show abstract

A Correlation of Electrochemical Oxidation and Ionization Potentials of Group 4B Dimetals

Abstract: Correlations of ionization potentials and electrochemical oxidation potentials for group 4B dimetals were obtained.

Cited by 31 publications

References 13 publications

Complexes of germanium chlorides (RnGeCl4-n, n=0-3; R=Me, Ph) with redox active N-heteroaromatic ligands: an electrochemical study

Complexes of germanium chlorides (RnGeCl4-n, n=0-3; R=Me, Ph) with redox active N-heteroaromatic ligands: an electrochemical study

Oligosilanylated Silocanes

Generation of pyridyl coordinated organosilicon cation pool by oxidative Si-Si bond dissociation

Contact Info

Product

Resources

About

A Correlation of Electrochemical Oxidation and Ionization Potentials of Group 4B Dimetals

Abstract: Correlations of ionization potentials and electrochemical oxidation potentials for group 4B dimetals were obtained.

Cited by 31 publications

References 13 publications

Complexes of germanium chlorides (RnGeCl4-n, n=0-3; R=Me, Ph) with redox active N-hetero­aromatic ligands: an electrochemical study

Complexes of germanium chlorides (RnGeCl4-n, n=0-3; R=Me, Ph) with redox active N-hetero­aromatic ligands: an electrochemical study

Oligosilanylated Silocanes

Generation of pyridyl coordinated organosilicon cation pool by oxidative Si-Si bond dissociation

Contact Info

Product

Resources

About

Complexes of germanium chlorides (RnGeCl4-n, n=0-3; R=Me, Ph) with redox active N-heteroaromatic ligands: an electrochemical study

Complexes of germanium chlorides (RnGeCl4-n, n=0-3; R=Me, Ph) with redox active N-heteroaromatic ligands: an electrochemical study