title: Design and synthesis of quasi-diastereomeric molecules with unchanging central, regenerating axial and switchable helical chirality via cleavage and formation of Ni(II)-O and Ni(II)-N coordination bonds.
abstract: We describe herein the design and synthesis of asymmetric, pentadentate ligands, which are able to coordinate to Ni(II) cations leading to quasi-diastereomeric complexes displaying two new elements of chirality: stereogenic axis and helix along with configurational stabilization of the stereogenic center on the nitrogen. Due to the stereocongested structural characteristics of the corresponding Ni(II) complexes, the formation of quasi-diastereomeric products is highly stereoselective providing formation of only two, (R(a)*,M(h)*,R(c)*) and (R(a)*,P(h)*,R(c)*), out of the four possible stereochemical combinations. The reversible quasi-diastereomeric transformation between the products (R(a)*,M(h)*,R(c)*) and (R(a)*,P(h)*,R(c)*) occurs by intramolecular trans-coordination of Ni-NH and Ni-O bonds providing a basis for a chiral switch model.
authors.affiliation: Department of Organic Chemistry I, Faculty of Chemistry, University of the Basque Country, 20018 San Sebastián, Spain ; IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain.
authors.forename: Vadim A
authors.initials: VA
authors.lastname: Soloshonok
authors.forename: José Luis
authors.initials: JL
authors.lastname: Aceña
authors.forename: Hisanori
authors.initials: H
authors.lastname: Ueki
authors.forename: Jianlin
authors.initials: J
authors.lastname: Han