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Bachman, Robert E.; Fiseha, Ashebir; Pollack, Steven K.

doi:10.1023/a:1009571228776

Cited by 9 publications

(4 citation statements)

References 6 publications

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“…It should be noted that the central C=C bond in uncoordinated butatrienes is, on the con trary, essentially shorter than the terminal C=C bonds (see, for example, Refs. [4][5][6]. The interaction between the C(2)=C (3) …”

Section: Methodsmentioning

confidence: 99%

First structurally characterized five-membered hafnacyclocumulene Cp2Hf(η4-ButC4But)

et al. 2008

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Section: Methodsmentioning

confidence: 99%

First structurally characterized five-membered hafnacyclocumulene Cp2Hf(η4-ButC4But)

et al. 2008

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“…In its structure, complex 8 is similar to 1 and other earlier synthesized seven-membered zirconacyclocumulenes (see above). The central C(2)–C(3) bond in the butatrienyl moiety of each independent molecule of 8 (1.315(8), 1.303(12), and 1.330(11) Å; av 1.32 Å) is elongated as compared to the corresponding central CC bond (1.241–1.276 Å; av 1.26 Å) in usual, purely organic uncoordinated butatrienes, − which suggests the coordination of this C(2)–C(3) bond with the zirconium atom. The Zr(1)–C(1) and Zr(1)–C(6) bond lengths in the three molecules of 8 are equal to 2.394(8)–2.442(6) Å (av 2.42 Å) and 2.390(6)–2.397(8) Å (av 2.39 Å), respectively, and are comparable with the Zr(1)···C(2) and Zr(1)···C(3) distances (2.389(8)–2.407(5) Å; av 2.40 Å and 2.375(9)–2.438(8) Å; av 2.41 Å), which is consistent with the assumption of the involvement of the C(2)–C(3) bond in the interaction with the zirconium center.…”

Section: Resultsmentioning

confidence: 99%

Thermal Isomerization of the Buchwald Seven-Membered Zirconacyclocumulene and Its Interaction with Acetylenes. Synthesis and Structures of Novel Seven-Membered Zirconacyclocumulene Complexes

et al. 2015

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On prolonged heating of the Buchwald seven-membered zirconacyclocumulene Cp 2 Zr[η 4 -Me 3 SiC 4 (SiMe 3 )− C(C 2 SiMe 3 )CSiMe 3 ] (1) in toluene at 100 °C, the isomerization of 1 takes place with the formation of a seven-membered zirconacyclocumulene complex, Cp 2 Zr[η 4 -Me 3 SiC 4 (SiMe 3 )−C(SiMe 3 )C(C 2 SiMe 3 )] (8), containing the Me 3 SiCC group in α-position and the SiMe 3 group in β-position with respect to the Zr atom. A remarkable peculiarity of complex 8 is its ability to undergo a rapid degenerate rearrangement at room temperature in toluene solution, as a result of which only two rather than four singlets of the Me 3 Si groups are observed in the 1 H NMR spectrum of 8 under such conditions. At temperatures below 200 K, the rate of this rearrangement decreases and, as a consequence, the 1 H NMR spectrum of 8 acquires the normal view. If 1 is heated at 100 °C in the presence of acetylenes such as 1,4-bis(tert-butyl)butadiyne ( t BuCC−CC t Bu) and tolane, the corresponding seven-membered zirconacyclocumulenes, viz., Cp 2 Zr[η 4 -t BuC 4 ( t Bu)−C(C 2 SiMe 3 )CSiMe 3 ] ( 7) and Cp 2 Zr[η 4 -Me 3 SiC 4 (SiMe 3 )−C(Ph)CPh] (14), are formed along with free Me 3 SiCC−CCSiMe 3 . The interaction of 1 with 1,4diphenylbutadiyne (PhCC−CCPh) at 100 °C leads to the formation of a mixture of products, from which a zirconacyclopentadiene metallacycle, Cp 2 Zr[η 2 -PhCC(C 2 Ph)−C(C 2 Ph)CPh] (10), as well as seven-membered zirconacyclocumulenes Cp 2 Zr[η 4 -PhC 4 (Ph)−C(C 2 SiMe 3 )CSiMe 3 ] (11), Cp 2 Zr[η 4 -Me 3 SiC 4 (SiMe 3 )−C(C 2 Ph)CPh] (12), and Cp 2 Zr[η 4 -PhC 4 (Ph)−C(C 2 Ph)CPh] (13) were isolated. The structures of 8, 9, 10, 12, and 14 have been established by X-ray crystallography. The mechanism of the reactions found is discussed.

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“…We will report on that study in a subsequent publication. 12 BPMB when dissolved in either ethereal or aromatic hydrocarbon solvents produces a white fibrous precipitate upon standing. No initiator is required for BPMB to undergo 1,4 polymerization.…”

Section: Resultsmentioning

confidence: 99%

Butatriene-Based Polymer Chemistry. 2. Synthesis and Characterization of Poly[1,1,4,4-bis(pentamethylene)-1,2,3-butatriene]^,1

1997

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The cumulene 1,1,4,4-bis(pentamethylene)butatriene has been shown to undergo a thermally induced 1,4 free-radical polymerization to yield a crystalline polymer with a unique nonconjugated acetylene containing backbone. This polymerization occurs in both the melt and in solution. Typical free-radical inhibitors prevent the thermally induced polymerization. The reaction occurs in the presence or absence of free-radical initiators. The polymer is crystalline with a triclinic unit cell (a ) 9.87 Å, b ) 6.10 Å, c ) 4.97 Å, R ) 113.7°, ) 85.2°, γ ) 100.6°). No melting or glass transition is observed via differential calorimetry, but an irreversible exothermic transition is observed from both solution and melt polymerized material. This is interpreted as a cold crystallization process. Trapping of the polymerizing monomer with TEMPO leads to soluble oligomers. † This paper is dedicated to Professor Shelton Bank on the occasion of his 65th birthday.

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Cited by 9 publications

References 6 publications

First structurally characterized five-membered hafnacyclocumulene Cp2Hf(η4-ButC4But)

First structurally characterized five-membered hafnacyclocumulene Cp2Hf(η4-ButC4But)

Thermal Isomerization of the Buchwald Seven-Membered Zirconacyclocumulene and Its Interaction with Acetylenes. Synthesis and Structures of Novel Seven-Membered Zirconacyclocumulene Complexes

Butatriene-Based Polymer Chemistry. 2. Synthesis and Characterization of Poly[1,1,4,4-bis(pentamethylene)-1,2,3-butatriene]^,1

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Untitled

Cited by 9 publications

References 6 publications

First structurally characterized five-membered hafnacyclocumulene Cp2Hf(η4-ButC4But)

First structurally characterized five-membered hafnacyclocumulene Cp2Hf(η4-ButC4But)

Thermal Isomerization of the Buchwald Seven-Membered Zirconacyclocumulene and Its Interaction with Acetylenes. Synthesis and Structures of Novel Seven-Membered Zirconacyclocumulene Complexes

Butatriene-Based Polymer Chemistry. 2. Synthesis and Characterization of Poly[1,1,4,4-bis(pentamethylene)-1,2,3-butatriene],1

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Butatriene-Based Polymer Chemistry. 2. Synthesis and Characterization of Poly[1,1,4,4-bis(pentamethylene)-1,2,3-butatriene]^,1