Adding the right (or left) twist to tris-chelate complexes – coordination chemistry of chiral oxazolylphenolates with M<sup>3+</sup>ions (M = Al or lanthanide)
作者:Helen C. Aspinall、John Bacsa、Oliver D. Beckingham、Edward G. B. Eden、Nicholas Greeves、Matthew D. Hobbs、Frances Potjewyd、Marc Schmidtmann、Christopher D. Thomas
DOI:10.1039/c3dt52366g
日期:——
A series of homoleptic tris-chelate complexes ML3 (M = Al or rare earth; L = chiral or achiral oxazolyl phenolate or -naphtholate) is reported. In all cases, complexes crystallize as mer-isomers and complete diastereoselectivity is observed on crystallization of the complexes: ML3 crystallize with Î-helicity at the metal where L = (S)-oxazolylphenolate. Complexes have been characterized in solution by NMR spectroscopy, demonstrating rapid ligand exchange at ambient temperature for rare earth complexes, and slow exchange on the NMR timescale for complexes of Al; in all cases the mer-isomer is observed exclusively. Crystal structures are reported for [YL3]2 (L = (S)-2-(4-isopropyl-4,5-dihydrooxazol-2-yl)-phenolate), mer-[YbL3] (L = (S)-2-(4-isopropyl-4,5-dihydrooxazol-2-yl)-6-methylphenolate) and mer-[AlL3] (L = (S)-2-(4-isopropyl-4,5-dihydrooxazol-2-yl)-6-methylphenolate, L = (S)-2-(4-isopropyl-4,5-dihydrooxazol-2-yl)-6-cyanophenolate), L = (S)-1-(4-isopropyl-4,5-dihydrooxazol-2-yl)naphthalen-2-olate, L = 1-(4,4-dimethyl-4,5-dihydrooxazol-2-yl)naphthalen-2-olate).
报道了一系列同配体三齿螯合物 ML3(M = Al 或稀土元素;L = 手性或非手性的噁唑基酚醛或萘酸盐)。在所有情况下,化合物以 mer-异构体结晶,并且在化合物结晶时观察到完全的差向选择性:当 L = (S)-噁唑基酚醛时,ML3 以 Î-螺旋性结晶。通过核磁共振光谱法对溶液中的化合物进行了表征,显示稀土化合物在室温下具有快速的配体交换,而铝化合物在核磁共振时间尺度上表现出缓慢的交换;在所有情况下,独 exclusively 观察到 mer-异构体。报告了以下化合物的晶体结构:[YL3]2(L = (S)-2-(4-异丙基-4,5-二氢噁唑-2-基)-苯酸盐),mer-[YbL3](L = (S)-2-(4-异丙基-4,5-二氢噁唑-2-基)-6-甲基苯酸盐)和 mer-[AlL3](L = (S)-2-(4-异丙基-4,5-二氢噁唑-2-基)-6-甲基苯酸盐,L = (S)-2-(4-异丙基-4,5-二氢噁唑-2-基)-6-氰苯酸盐),L = (S)-1-(4-异丙基-4,5-二氢噁唑-2-基)萘酸盐,L = 1-(4,4-二甲基-4,5-二氢噁唑-2-基)萘酸盐。