Interaction of the Negishi reagent Cp2ZrBun 2 with 1,4-bis(tert-butyl)butadiyne

Burlakov, Vladimir V.; Bogdanov, V. S.; Spannenberg, Anke; Petrovskii, P. V.; Baumann, Wolfgang; Arndt, Perdita; Minacheva, M. Kh.; Strunin, B.N.; Rosenthal, Uwe; Shur, V. B.

doi:10.1007/s11172-012-0023-8

Cited by 14 publications

(18 citation statements)

References 20 publications

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“…An X-ray diffraction study of 10 has shown that it represents a zirconacyclopentadiene derivative formed by a Cp 2 Complex 11 was isolated from the mixture in 3% yield. In contrast to 10, this compound could not be obtained as crystals suitable for an X-ray analysis, but its structure was unequivocally established by elemental analysis and 1 H and 13 C NMR spectra.…”

Section: Methodsmentioning

confidence: 99%

“…The ability of acetylene complexes of zirconocene to form seven-membered zirconacyclocumulenes in the interaction with conjugated diacetylenes has earlier been demonstrated. 2,5,6 Complex 12 is dominant (37%) in the product mixture and was obtained in an analytically pure state in 17% yield. According to X-ray diffraction data, it represents an isomer of 11 and contains the Me 3 Si groups rather than the Ph groups at the terminal carbon atoms of the butatrienyl fragment.…”

Section: Methodsmentioning

confidence: 99%

“…In the absence of acetylenes, the starting 1 is converted into the isomeric seven-membered zirconacyclocumulene complex differing from 1 by the mutual arrangement of the Me 3 Si and Me 3 SiCC substituents at the carbon atoms of the olefinic CC bond of the zirconacycle. The mechanism of these transformations becomes understandable if we assume the existence of an equilibrium at 100°C between 1, the corresponding five-membered zirconacyclocumulene Cp 2 …”

Section: ■ Conclusionmentioning

confidence: 99%

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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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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: ■ Conclusionmentioning

confidence: 99%

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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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“…The investigation of strained metallacycles, containing double, cumulated, and triple CC bonds is a trend in the chemistry of group 4 elements. − The profound interest is caused by the high thermal stability of its nontrivial structure in comparison with their organic analogues. Since the pioneered works of Buchwald’s, Burlakov and Rosenthal, − the two types of metallacycles containing [3]cumulene fragments 1 an 2 are known for group 4 metallocenes (Figure ).…”

Section: Introductionmentioning

confidence: 99%

“…The structures 1 and 2 and related compounds 3 and 4 were studied earlier using various computational − and experimental methods. − Based on the bond distances, electron density distributions, vibrational spectra, and reactivity, cyclocumulenes 1 and 2 are usually considered by means of two resonance forms. − ,, For 1 , it is M-cyclocumulene and diacetylene complex (Scheme ), and for 2 , it is M-cyclocumulene and M-cyclopentadiene with a coordinated lateral alkyne branch (Scheme ). It is well known that frontier canonical molecular orbitals (CMOs) of the Cp 2 M moiety, , which are essentially d-orbitals of the metal, are located in the bisecting plane.…”

Section: Introductionmentioning

confidence: 99%

Aromaticity of 5- and 7-Membered Metallacyclocumulenes of Group 4

Aysin

Bukalov

2021

Organometallics

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Using the recent aromatic criteria, the conjugation and aromatic properties of group 4 metallacyclocumulenes Cp 2 M-η 4 −(R)CCCC−R (1) and Cp 2 M-η 3 (R−C CCC(R)−R(C) CR) (2) (M = Ti, Zr, Hf) were studied. To these nontrivial bonded metallacycles, the most recent universal criteria of aromaticity were applied that do not require any parametrisation such as isomerisation stabilization energy, electron density of delocalized bonds (EDDB), nuclear independent chemical shift, and gauge-included magnetically induced currents (GIMIC). All methods used indicated the absence of the common π-type aromaticity. The most efficient EDDB and GIMIC methods showed in-plane aromatic pathway in 5-membered cycle 1 against 7-membered 2. The distribution of the induced currents (ICs) for such unique aromaticity type was demonstrated. It shows that the diatropic ICs of 1 are located both inside and outside the cycle. The population analysis of molecular orbitals and natural orbitals for delocalized bonds revealed the abidance to the 4n + 2 electron rule. According to EDDB and GIMIC data, the degree of aromaticity for 1 tends to decrease from Ti to Zr and Hf. Article pubs.acs.org/Organometallics

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Aktivierung von Kohlenstoff‐Kohlenstoff Bindungen durch Chrom(I): Spaltung von Dialkinen durch einen 11‐Elektronenkomplex

Braun,

Bruckhoff,

Ott

et al. 2024

Angewandte Chemie

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A 11‐electron T‐shaped chromium(I)‐complex was obtained by reduction of a PNP‐supported chromium (II) iodide complex. Its d5 high spin electronic structure was characterized employing paramagnetic NMR, EPR, UV‐Vis and magnetic measurements (SQUID). The complex readily reacts with conjugated dialkynes to cleave the internal C‐C‐bond, forming the respective acetylide complexes. Varying the alkyne substituents enabled the isolation and characterization of dinuclear dialkynedichromium intermediates which thermally convert to the products.

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Interaction of the Negishi reagent Cp2ZrBun 2 with 1,4-bis(tert-butyl)butadiyne

Cited by 14 publications

References 20 publications

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

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

Aromaticity of 5- and 7-Membered Metallacyclocumulenes of Group 4

Aktivierung von Kohlenstoff‐Kohlenstoff Bindungen durch Chrom(I): Spaltung von Dialkinen durch einen 11‐Elektronenkomplex

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