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Zinc Complexes of Bipyrrolidine‐Based Diamine‐Diphenolato and Diamine‐Diolato Ligands: Predetermination of Helical Chirality Around Tetrahedral Centres
Author(s) -
Sergeeva Ekaterina,
Press Konstantin,
Goldberg Israel,
Kol Moshe
Publication year - 2013
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201300151
Subject(s) - chemistry , diamine , ligand (biochemistry) , stereochemistry , chirality (physics) , zinc , crystallography , polymer chemistry , organic chemistry , receptor , biochemistry , chiral symmetry breaking , physics , quantum mechanics , nambu–jona lasinio model , quark
The coordination chemistry of chiral tetradentate dianionic ligands of the diamine‐diphenolato and diamine‐diolato families having the ( R , R )‐2,2′‐bipyrrolidine core around Zn II was investigated. Reactions with diethylzinc led to complexes of the type [{ONNO}Zn] for most ligands and to bridging dinuclear complexes of the type [μ‐Lig 4 (ZnEt) 2 ] for one of the diamine‐diolato ligands. Reactions with bis(hexamethyldisilazide)zinc led to complete conversions. Most complexes were obtained as mononuclear complexes. The least bulky Salan ligand, Lig 3 , led to an equilibrium between mononuclear and dinuclear complexes in noncoordinating solvents. All ligands were found to wrap around the tetrahedral zinc with very high diastereoselectivities supporting predetermined chiral induction from the bipyrrolidine core to the helical ligand wrapping. Molecular structures determined by single‐crystal X‐ray diffraction for two complexes of the type [{ONNO}Zn] substantiated the predicted Δ wrapping of the ( R , R )‐based ligands. In contrast, representative Salan and diamine‐diolato ligands assembled around the trans ‐1,2‐diaminocyclohexane core led to diastereomer mixtures of the corresponding complexes.