Organometallic chemistry

摘要

Many ligands for asymmetric catalysis are based on ligands derived from optically pure diamines. This section of Highlights opens with several papers concerning ligands of this kind. Titanium sulphonamide complexes related to structure (1), for instance, have emerged as extremely useful systems for stereochemically controlled reactions. A representative complex in this series has now been studied crystallographically (Gagne et al, Organometallics, 1998, 17, 216). Its structure is unremarkable except that the C~2 symmetry of the complex is broken by weak coordination of one sulphonyl oxygen to the metal. Perhaps more interesting is the observation that reaction of this material with phenols causes disproportionation as indicated in Reaction 1, implying that asymmetric catalysis involving these complexes may be complicated by similar disproportionation processes.