title: 2,2'-Bipyrrolidine versus 1,2-diaminocyclohexane as chiral cores for helically wrapping diamine-diolate ligands.
abstract: The synthesis of chiral tetradentate dianionic diamine-diolate ligands assembled around either N,N'-dimethyl-trans-1,2-diaminocyclohexane or 2,2'-bipyrrolidine is described. These ligands wrap in a fac-fac helical mode around octahedral titanium and zirconium centers giving chiral-at-metal complexes. Diaminocyclohexane was found to be a poor chiral motif for diastereoselective helical wrapping, and all complexes of this family were obtained as mixtures of stereoisomers. In contrast, bipyrrolidine was found to be a perfect chiral motif for helical wrapping, and the corresponding diamine-diolate complexes were obtained as (enantiomerically pure) single diastereomers.
authors.affiliation: School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Sergeeva
authors.forename: Jacob
authors.initials: J
authors.lastname: Kopilov
authors.forename: Israel
authors.initials: I
authors.lastname: Goldberg
authors.forename: Moshe
authors.initials: M
authors.lastname: Kol
mesh_terms: D018360:Crystallography, X-Ray; D003514:Cyclohexylamines / Q000737:chemistry*; D003959:Diamines / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D011759:Pyrrolidines / Q000737:chemistry*; D013237:Stereoisomerism; D014025:Titanium / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry
chemical_list: D003514:Cyclohexylamines; D003959:Diamines; D008024:Ligands; D009942:Organometallic Compounds; D011759:Pyrrolidines; D015040:Zirconium; D014025:Titanium