Half-sandwich complexes [RhCl(pymox)Cp*][SbF6]
(1â7)
(pymox = pyridyloxazoline) have been synthesised as single diastereomers. Treatment of these with AgSbF6 generates dications [Rh(OH2)(pymox)Cp*]2+ which are fluxional at room temperature and which are enantioselective catalysts for the DielsâAlder reaction of methacrolein and cyclopentadiene. Treatment of the dication [Rh(OH2)(iPr-pymox)Cp*]2+ with [X]â gives [RhX(iPr-pymox)Cp*][SbF6]
(X = Br, I) as single diastereomers whilst reaction with 4-Mepy (4-methylpyridine) gives [Rh(4-Mepy)(iPr-pymox)Cp*][SbF6] as a mixture of diastereomers. Two complexes, [RhCl(iPr-pymox)Cp*][SbF6]
(3) and [RhCl(Bz-pymox)Cp*][SbF6]
(6) have been characterised by X-ray crystallography.
半夹心复合物[RhCl(PYMOX)Cp*][SbF6] (1â7)(PYMOX=
吡啶恶唑啉)以非对映单体形式合成。用 AgSbF6 处理这些非对映异构体可生成二阳离子 [Rh(OH2)(pyMOx)Cp*]2+,它们在室温下具有通性,是甲基
丙烯醛和
环戊二烯的 DielsâAlder 反应的对映选择性催化剂。用[X]-处理二价化合物[Rh(OH2)(iPr-pyMOx)Cp*]2+,可得到[RhX(iPr-pyMOx)Cp*][SbF6](X = Br,I)单一非对映异构体,而与 4-
甲基吡啶(4-methylpyridine)反应,可得到非对映异构体混合物[Rh(4-Mepy)(iPr-pyMOx)Cp*][SbF6]。两种配合物,即 [RhCl(iPr-pyMOx)Cp*][SbF6] (3) 和 [RhCl(Bz-pyMOx)Cp*][SbF6] (6) 已通过 X 射线晶体学进行了表征。