The First X-ray Structure Determination of an Optically Pure Bismuthane
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- 作者：Toshihiro Murafuji ; Kohichi Satoh ; Yoshikazu Sugihara ; and Nagao Azuma
- 刊名：Organometallics
- 出版年：1998
- 出版时间：April 27, 1998
- 年：1998
- 卷：17
- 期：9
- 页码：1711 - 1715
- 全文大小：75K
- 年卷期：v.17,no.9(April 27, 1998)
- ISSN：1520-6041
文摘
(4-Chlorophenyl){(S)-2-[(R)-1-(dimethylamino)ethyl]ferrocenyl}iodobismuthane(3b), thefirst example of an optically pure bismuthane, was synthesized withexclusive stereoselectivity using Bi-N intramolecular coordination and the planar chiralityof ferrocene. Thevariable-temperature 1H NMR spectra measured in the rangefrom -50 to +50 
C in CDCl3revealed that no epimerization takes place at the bismuth center.An X-ray crystallographicstudy demonstrated that the bismuth atom is diastereoselectivelyintroduced into thesubstituted cyclopentadienyl ring and that the 4-chlorophenyl groupoccupies the exo positiontoward the iron atom. The absolute configuration around thebismuth atom was determinedto be R. The longer intramolecular Bi-N distance of3b [2.71(1) Å] compared with those ofchloro{2-[(R)-1-(dimethylamino)ethyl]phenyl}phenylbismuthane(1a,b) [2.55(2), 2.57(2)Å,respectively] indicates a weaker Bi-N coordination in the ferrocenesystem. The specificrotation of 3b, [
]D23 -546(c 1.0, CHCl3), is negatively much larger thanthat ofbis(4-chlorophenyl){(S)-2-[(R)-1-(dimethylamino)ethyl]ferrocenyl}bismuthane(5b), []D23-330 (c 1.0, CHCl3), which is considered to bethe result of generation of the optically activecenter at bismuth.
C in CDCl3revealed that no epimerization takes place at the bismuth center.An X-ray crystallographicstudy demonstrated that the bismuth atom is diastereoselectivelyintroduced into thesubstituted cyclopentadienyl ring and that the 4-chlorophenyl groupoccupies the exo positiontoward the iron atom. The absolute configuration around thebismuth atom was determinedto be R. The longer intramolecular Bi-N distance of3b [2.71(1) Å] compared with those ofchloro{2-[(R)-1-(dimethylamino)ethyl]phenyl}phenylbismuthane(1a,b) [2.55(2), 2.57(2)Å,respectively] indicates a weaker Bi-N coordination in the ferrocenesystem. The specificrotation of 3b, []D23 -546(c 1.0, CHCl3), is negatively much larger thanthat ofbis(4-chlorophenyl){(S)-2-[(R)-1-(dimethylamino)ethyl]ferrocenyl}bismuthane(5b), []D23-330 (c 1.0, CHCl3), which is considered to bethe result of generation of the optically activecenter at bismuth.