Stereoisomerism in bridged octahedral dimeric complexes with tetradentate ligands. Diastereospecific formation of syn-delta delta-(cis-beta-L)TiO2 (L-chiral salen type ligands)
The first two examples of the successful application of chiral salen ligands for diastereoselective syntheses of dinuclear Ti(IV), (L1Ti)2O2 and (PdI2L2Ti)2O2 species with defined chirality and geometry at the metal centre are presented. The structure of the complexes was established by X-ray structural analysis. Both complexes have similar structural features: (1) chiral salen ligands have cis-beta configuration around Ti centres, (2) (R,R) chirality of ligands induces delta helicity of ligand, and (3) syn arrangement of ligand donor atoms in relation to the TiO2Ti plane. Stereoselective effects of the dimers are discussed engaging available literature data. A model has been proposed to rationalise high syn selectivity in the formation of dimers.
Tararov
VI
A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Moscow, Russia.
Larichev
VS
Moscalenko
MA
Yashkina
LV
Khrustalev
VN
Antipin
MYu
Borner
A
Belokon
YN