Reactions of (Butadiene)tantalocene Cation with Alkyl Isocyanides
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- 作者：Hans Christian Strauch ; Birgit Wibbeling ; Roland Frö ; hlich ; Gerhard Erker ; Heiko Jacobsen ; and Heinz Berke
- 刊名：Organometallics
- 出版年：1999
- 出版时间：September 13, 1999
- 年：1999
- 卷：18
- 期：19
- 页码：3802 - 3812
- 全文大小：212K
- 年卷期：v.18,no.19(September 13, 1999)
- ISSN：1520-6041
文摘
Treatment of (
4-s-trans-butadiene)tantalocene cation (3, with methyltris(pentafluorophenyl)borane anion) with tert-butyl isocyanide (4 h, at 45 
C in bromobenzene) yields the[(2-butadiene)(C
NCMe3)TaCp2+] complex 4a (70% isolated, 
(CNR) 2164 cm-1). Likewisetreatment with n-butyl or cyclohexyl isocyanide gives the analogous products 4b and 4c,respectively. The cyclohexyl isocyanide adduct 4c was characterized by X-ray diffraction. Itshows the 2-butadiene ligand oriented at the front of the Cp2Ta+ bent metallocene wedgewith the noncoordinated butadiene vinyl group located in the "vinyl-inside" position. TheTa-CN-R unit is almost linear (angles Ta-C-N = 177.2(5), CN-R = 174.0(8);d(CN) = 1.152(6) Å). Photolysis of [(butadiene)TaCp2+] (3) with excess cyclohexyl isocyanidefollowed by thermal treatment gave rise to the formation of [bis(
C-cyclohexyl isocyanide)TaCp2+] (8, with [CH3B(C6F5)3-] counteranion; >50% isolated, (CNR) 2134 and 2088 cm-1).Complex 8 was characterized by an X-ray crystal structure analysis. It shows a pseudotetrahedral [Cp2Ta(CNR)2+] cation (R = C6H11). The Ta-CN-R units are both slightlybent at nitrogen (angles CN-R = 169.0(13) and 163.7(8); the corresponding Ta-C-Nangles are 179.4(9) and 177.4(7)). The bonding situations of complexes 4 and 8 were analyzedby DFT calculations. The computational study shows that metal to isonitrile back-bondingdoes not contribute significantly to the Cp2Ta+-CNR bonding interaction in thesecomplexes. The bonding between Cp2Ta+ and the CNR ligands is dominated by electrostaticeffects.
4-s-trans-butadiene)tantalocene cation (3, with methyltris(pentafluorophenyl)borane anion) with tert-butyl isocyanide (4 h, at 45 C in bromobenzene) yields the[(2-butadiene)(CNCMe3)TaCp2+] complex 4a (70% isolated, (CNR) 2164 cm-1). Likewisetreatment with n-butyl or cyclohexyl isocyanide gives the analogous products 4b and 4c,respectively. The cyclohexyl isocyanide adduct 4c was characterized by X-ray diffraction. Itshows the 2-butadiene ligand oriented at the front of the Cp2Ta+ bent metallocene wedgewith the noncoordinated butadiene vinyl group located in the "vinyl-inside" position. TheTa-CN-R unit is almost linear (angles Ta-C-N = 177.2(5), CN-R = 174.0(8);d(CN) = 1.152(6) Å). Photolysis of [(butadiene)TaCp2+] (3) with excess cyclohexyl isocyanidefollowed by thermal treatment gave rise to the formation of [bis(C-cyclohexyl isocyanide)TaCp2+] (8, with [CH3B(C6F5)3-] counteranion; >50% isolated, (CNR) 2134 and 2088 cm-1).Complex 8 was characterized by an X-ray crystal structure analysis. It shows a pseudotetrahedral [Cp2Ta(CNR)2+] cation (R = C6H11). The Ta-CN-R units are both slightlybent at nitrogen (angles CN-R = 169.0(13) and 163.7(8); the corresponding Ta-C-Nangles are 179.4(9) and 177.4(7)). The bonding situations of complexes 4 and 8 were analyzedby DFT calculations. The computational study shows that metal to isonitrile back-bondingdoes not contribute significantly to the Cp2Ta+-CNR bonding interaction in thesecomplexes. The bonding between Cp2Ta+ and the CNR ligands is dominated by electrostaticeffects.