Dalla Cort Antonella, Mandolini Luigi, Palmieri Giovanni, Pasquini Chiara, Schiaffino Luca
IMC-CNR, Università La Sapienza, Box 34-ROMA 62, 00185 Roma, Italy.
Chem Commun (Camb). 2003 Sep 7(17):2178-9. doi: 10.1039/b306478f.
In complexes with the uranyl dication salophen ligands are highly puckered. This implies that non-symmetrically substituted uranyl-salophen derivatives exist in principle as a pair of enantiomers. However, due to easy disrotations about the bonds connecting the phenoxide units to the imine carbons, the rate of interconversion between enantiomeric forms of simple, sterically unhindered compounds is extremely fast. Bulky substituents in appropriate positions decrease the interconversion rate and make this novel type of inherent chirality detectable by 1H and 13C NMR.
在与双氧铀二价阳离子形成的配合物中,萨罗酚配体高度褶皱。这意味着非对称取代的双氧铀 - 萨罗酚衍生物原则上以一对对映体的形式存在。然而,由于围绕连接酚氧基单元与亚胺碳的键的容易的顺旋,简单的、空间位阻小的化合物的对映体形式之间的互变速率极快。在适当位置的大体积取代基降低了互变速率,并使得这种新型的固有手性能够通过¹H和¹³C核磁共振检测到。