Interaction of the five-membered zirconacyclocumulene complex Cp2Zr(η4-tBuC4tBu) with acetylenes. Synthesis of zirconacyclopentadienes and seven-membered zirconacyclocumulenes
摘要:
In the interaction of the five-membered zirconacyclocumulene Cp2Zr(eta(4)-(BuC4Bu)-Bu-t-Bu-t) (6) with 1,4-bis(trimethylsilyl)butadiyne Me3SiC C-C CSiMe3 in toluene at 60-80 degrees C, two isomeric zirconacyclopentadiene complexes (7) and (8) are formed in 4.4-4.7 : 1 ratio. Complex 7 has been isolated from the solution in the individual state and its structure Cp2Zr[eta(2)-(BuC)-Bu-t=C(C-2 Bu-t)-C(SiMe3)=C(C2SiMe3)] has been determined by X-ray crystallography. Prolonged heating of a mixture of 6 and Me3SiC C-C CSiMe3 at 100 degrees C leads to a gradual disappearance of the resulting zirconacyclopentadienes and to the formation of the seven-membered zirconacyclocumulene complex Cp2Zr[eta(4)-(BuC4)-Bu-t(Bu-t)-C(C2SiMe3)]=CSiMe3] (9) as the main product and two its analogues, viz., Cp2Zr[eta(4)-Me3SiC4(SiMe3)-C(C2SiMe3)]=CSiMe3] (1) and Cp2Zr[eta(4)-(BuC4)-Bu-t(Bu-t)-C(C-2 Bu-t)=(CBu)-Bu-t] (2) as the admixtures. The same products are produced from individual compound 7 at 100 degrees C. Heating of complex 6 with tolane and phenylacetylene in toluene at 100 degrees C also gives rise to the corresponding zirconacyclopentadiene metallacycles, viz. Cp2Zr[eta(2)-(BuC)-Bu-t=C(C-2 Bu-t)-C(Ph)=CPh] (10) and Cp2Zr[eta(2)-(BuC)-Bu-t=C(C-2 Bu-t)-CH]=CPh] (11). However these metallacycles do not form seven-membered zirconacyclocumulene complexes in any significant amounts even under prolonged keeping of the mixture at 100 degrees C. The structure of complexes 9-11 has also been established by X-ray crystallography. Mechanisms of the reactions found are discussed. (C) 2013 Elsevier B.V. All rights reserved.
Interaction of the five-membered zirconacyclocumulene complex Cp2Zr(η4-tBuC4tBu) with acetylenes. Synthesis of zirconacyclopentadienes and seven-membered zirconacyclocumulenes
摘要:
In the interaction of the five-membered zirconacyclocumulene Cp2Zr(eta(4)-(BuC4Bu)-Bu-t-Bu-t) (6) with 1,4-bis(trimethylsilyl)butadiyne Me3SiC C-C CSiMe3 in toluene at 60-80 degrees C, two isomeric zirconacyclopentadiene complexes (7) and (8) are formed in 4.4-4.7 : 1 ratio. Complex 7 has been isolated from the solution in the individual state and its structure Cp2Zr[eta(2)-(BuC)-Bu-t=C(C-2 Bu-t)-C(SiMe3)=C(C2SiMe3)] has been determined by X-ray crystallography. Prolonged heating of a mixture of 6 and Me3SiC C-C CSiMe3 at 100 degrees C leads to a gradual disappearance of the resulting zirconacyclopentadienes and to the formation of the seven-membered zirconacyclocumulene complex Cp2Zr[eta(4)-(BuC4)-Bu-t(Bu-t)-C(C2SiMe3)]=CSiMe3] (9) as the main product and two its analogues, viz., Cp2Zr[eta(4)-Me3SiC4(SiMe3)-C(C2SiMe3)]=CSiMe3] (1) and Cp2Zr[eta(4)-(BuC4)-Bu-t(Bu-t)-C(C-2 Bu-t)=(CBu)-Bu-t] (2) as the admixtures. The same products are produced from individual compound 7 at 100 degrees C. Heating of complex 6 with tolane and phenylacetylene in toluene at 100 degrees C also gives rise to the corresponding zirconacyclopentadiene metallacycles, viz. Cp2Zr[eta(2)-(BuC)-Bu-t=C(C-2 Bu-t)-C(Ph)=CPh] (10) and Cp2Zr[eta(2)-(BuC)-Bu-t=C(C-2 Bu-t)-CH]=CPh] (11). However these metallacycles do not form seven-membered zirconacyclocumulene complexes in any significant amounts even under prolonged keeping of the mixture at 100 degrees C. The structure of complexes 9-11 has also been established by X-ray crystallography. Mechanisms of the reactions found are discussed. (C) 2013 Elsevier B.V. All rights reserved.