Unprecedented Formation of Azulenylidene Ligands by Reaction of the Vinylidene Ligand in Arylvinylidene Pentacarbonyl Complexes of Chromium and Tungsten with Alkoxyacetylenes
详细信息 查看全文
- 作者：Sylvia Hagmayer ; Angelika Frü ; h ; Thomas Haas ; Matthias Drexler ; Helmut Fischer
- 刊名：Organometallics
- 出版年：2007
- 出版时间：July 16, 2007
- 年：2007
- 卷：26
- 期：15
- 页码：3791 - 3801
- 全文大小：241K
- 年卷期：v.26,no.15(July 16, 2007)
- ISSN：1520-6041
文摘
Arylvinylidene(pentacarbonyl)chromium and -tungsten complexes [(CO)5M=C=C(C6H4R1-p)R2] (M= Cr, W; R1 = H; R2 = Me, C6H4R3-p [R3 = H, Me, OMe, Cl, tBu]; R1 = Me; R2 = C6H4Cl-p) reactwith alkoxyacetylenes, HC
COR' (R' = Et, tBu, adamantyl), by 1,3-addition of the CC triple bond tothe vinylidene ligand and ring expansion to give azulenylidene complexes [(CO)5M=C-CH=C(OR')C( CR)=CHCH=C(R)CH= CH]. When monosubstituted and unsymmetrically bis-substituted bis(aryl)vinylidene complexes are employed, mixtures of two isomers are obtained. In the two isomers thesubstituent either is attached to the seven-membered ring or resides in the para position of the phenylgroup. In general, the selectivity of the reactions is low; the isomeric ratio varies between 0.5 and 2depending on the metal and the substituent. DFT calculations on the reaction mechanism indicate thatthe reactions are initiated by a nucleophilic addition of the terminal carbon atom of the alkoxyacetyleneto the metal-bound C
atom of the vinylidene ligand. The low selectivity of the reactions is in accordwith the results of the calculations. The structure of several azulenylidene complexes was established byX-ray structure analyses.
COR' (R' = Et, tBu, adamantyl), by 1,3-addition of the CC triple bond tothe vinylidene ligand and ring expansion to give azulenylidene complexes atom of the vinylidene ligand. The low selectivity of the reactions is in accordwith the results of the calculations. The structure of several azulenylidene complexes was established byX-ray structure analyses.