One-Electron Reduction of Kinetically Stabilized Dipnictenes:  Synthesis of Dipnictene Anion Radicals

Sasamori, Takahiro; Mieda, Eiko; Nagahora, Noriyoshi; Sato, Kazunobu; Shiomi, Daisuke; Takui, Takeji; Hosoi, Yuzô; Furukawa, Yukio; Takagi, Noboru; Nagase, Shigeru; Tokitoh, Norihiro

doi:10.1021/ja064062m

Cited by 134 publications

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“…8 In addition, ³-bond compounds between heavier group 15 elements (P=P, As=As, Sb=Sb, and Bi=Bi, called dipnictenes) are known to afford stable anion radical species upon chemical reduction, showing their lower LUMO level and stable redox behavior. 9 From a standpoint of using a dipnictene moiety as a ³-spacer, the points of (ii) and (iii) should be clarified and investigated by the construction of bimetallic systems bearing a dipnictene moiety as a ³-spacer. Here again, it is expected that ³-bonds between heavier group 15 elements should be promisingly more effective ³-electron spacers than those of 2nd row elements.…”

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1,2-Bis(ferrocenyl)dipnictenes: Bimetallic Systems with a Pn=Pn Heavy π-Spacer (Pn: P, Sb, and Bi)

Sakagami

Sasamori

Sakai

et al. 2013

Bulletin of the Chemical Society of Japan

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1,2-Bis(ferrocenyl)dipnictenes bearing a Pn=Pn ³-spacer (Pn: P (1), Sb (2), and Bi (3)) between two ferrocenyl units have been synthesized as stable compounds. Not only their molecular structures and fundamental properties but also their redox behavior have been systematically disclosed. Interestingly, in the reduction region, the dipnictenes showed two pseudo-reversible one-electron redox couples at low temperature, suggesting possible generation of the corresponding radical anion and dianion species. On the other hand, they showed three-step one-electron oxidation processes in the oxidation region. The first two oxidation steps would correspond to those of the two ferrocenyl moieties, while the third step would be that of the Pn=Pn ³-spacer moiety, respectively. Thus, these 1,2-bis(ferrocenyl)dipnictenes with a Pn=Pn ³-spacer should be stable multiredox systems reflecting unique properties of a double bond between heavier 15 group elements. As a result, all Pn=Pn units (Pn: P, Sb, and Bi) were found to work as a more effective ³-spacer than those of 2nd row elements such as C=C and N=N.Organometallic ³-conjugated systems are attracting much interest from the viewpoint of showing interesting electronic, optical, and magnetic properties. In this research field, d³ conjugated systems of bimetallic complexes tethered with a ³-electron spacer, [M(Ligand)](³-electron spacer)[M(Ligand)] (M: transition metal), have been actively investigated.1 These compounds are a unique class of appropriate models of mixedvalence states giving insight on the ability of the ³-electron system as a ³-spacer in the context of fundamental organic electronic materials such as molecular switches and molecular wires.2 In this background, ferrocene is frequently used as an effective d-electron moiety in such d³ conjugated systems, because it should be a promisingly stable and effective redox system and amenable to modification with a variety of established substituents.3 Thus, ferrocenyl-based bimetallic d³ electron systems should be a touchstone for investigating the ability of a ³-electron system as a "³-spacer." Although several numbers of d³ conjugated systems with two ferrocenyl groups bridged by a ³-electron spacer have been reported to be investigated, e.g., Ph(Fc)C=C(Fc)Ph, 4 FcC¸CFc, 5 FcN=NFc 6 (Fc: ferrocenyl), and bis(ferrocenyl)thiophene derivatives, 7 the ³-electron systems in these compounds are limited to those consisting of 2nd row main group elements. The advantageous and required properties as a d³ electron system toward organometallic electronic materials should be (i) relatively low redox potential, (ii) stable multistep redox behavior, and (iii) controllable redox system. Regarding all of these points, ³-bonds between heavier main group elements are thought to be superior to those of 2nd row elements as a ³-spacer in d³ electron systems, because ³-bond compounds between heavier main group elements are known to exhibit smaller ³³* energy gaps than those of 2nd row elements due to the smaller overlapping of np orbitals. ...

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confidence: 99%

1,2-Bis(ferrocenyl)dipnictenes: Bimetallic Systems with a Pn=Pn Heavy π-Spacer (Pn: P, Sb, and Bi)

Sakagami

Sasamori

Sakai

et al. 2013

Bulletin of the Chemical Society of Japan

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“…The 29 Si NMR spectrum of 1 in C 6 D 6 showed a characteristic signal at 70.6 ppm, which is in the typical range for silicon atoms within a double bond [δ Si (tetraaryldisilenes): 53 66 ppm; δ Si (tetraalkyldisilenes): 90 103 ppm]. 9d The 1 H NMR spectrum of 1 in C 6 D 6 exhibited a pair of pseudo triplet peaks at 3.80 and 3.98 ppm, which should be assigned to the protons of the cyclopentadienyl (Cp) rings.…”

Section: The Synthesis Of D π Electron Systems Withmentioning

confidence: 99%

“…We have also reported that these heavier dipnictenes can be reduced by Li metal to give the corresponding anion radical species. 29 Hence, these π bonds between heavier group 15 elements should be able to work as effective π spacers between transition metal moieties. The simplest conceivable model compound for 1,2 bis(Fc)diphosphenes is Fc P P Fc, i.e.…”

Section: Design and Synthesis Of Bulky Fc Groups: Steric Protection Fmentioning

confidence: 99%

“…Even though the synthesis of the appropriate bulky precursors (28a,b) was thus accomplished, the synthetic strategy is rather laborious (6 steps from FcH; Scheme 7). Therefore, we developed an alternative synthetic route for these haloferrocenes: Lithiation of bromoferrocene with LiTMP (TMP 2,2,6,6 tetramethylpiperidide) resulted in the formation of 1,2 bromolithioferrocene, which was subjected to a Negishi cross coupling reaction with ArX (DmpI or DtpBr), affording the 1 bromo 2 Ar ferrocenes (29). 34 The introduction of another Ar group was achieved by subjecting 29 to a second Negishi cross coupling reaction to give the corresponding 1 bromo 2,5 Ar 2 ferrocenes (30).…”

Section: Design and Synthesis Of Bulky Fc Groups: Steric Protection Fmentioning

confidence: 99%

“…8b, 29 The dihedral angles between the E E C(Cp) and the Cp planes in 4 and 5 are 38 (E Sb) and 37 (E Bi), showing effective conjugation between the E E π electrons and those of the Fc moieties, relative to Ar E E Ar, where the aryl rings are aligned almost perpendicular to the E E C plane and hence prevent conjugation.…”

Section: Synthesis Of D π Electron Systems Bearing Two Bulky Fc Groupmentioning

confidence: 99%

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The Synthesis and Properties of Bimetallic d-^|^pi; Electron Systems Containing Metallocenyl Substituents of Fe or Ru, and ^|^pi;-Electron Spacers of Heavier Main Group Elements from Group 14 or 15

Sasamori

2014

J. Synth. Org. Chem. Jpn.

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Abstract:Relative to π electron systems between elements from the second row of the periodic table, those between heavier main group elements should exhibit higher HOMO and lower LUMO levels. Moreover, such π electron systems between heavier main group elements are expected to be good electron acceptors and donors, and they should also exhibit good electron transporting properties. With the ultimate goal to create unprecedented π electron systems between heavier main group elements in mind, we designed d π electron systems containing heavier main group elements in the π electron moiety and transition metals in the d electron moiety. In this account article, we present our recent progress on the generation of bimetallic ferrocenyl and ruthenocenyl based d π electron systems containing π bond spacers of heavier main group elements from group 14 or 15.

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π‐Electron Redox Systems of Heavier Group 15 Elements

Sasamori

Tokitoh

Streubel

2015

Organic Redox Systems

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One-Electron Reduction of Kinetically Stabilized Dipnictenes: Synthesis of Dipnictene Anion Radicals

Cited by 134 publications

References 41 publications

1,2-Bis(ferrocenyl)dipnictenes: Bimetallic Systems with a Pn=Pn Heavy π-Spacer (Pn: P, Sb, and Bi)

1,2-Bis(ferrocenyl)dipnictenes: Bimetallic Systems with a Pn=Pn Heavy π-Spacer (Pn: P, Sb, and Bi)

The Synthesis and Properties of Bimetallic d-^|^pi; Electron Systems Containing Metallocenyl Substituents of Fe or Ru, and ^|^pi;-Electron Spacers of Heavier Main Group Elements from Group 14 or 15

π‐Electron Redox Systems of Heavier Group 15 Elements

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