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[Ln(binolam) 3 ]⋅(OTf) 3 , a New Class of Propeller‐Shaped Lanthanide(III) Salt Complexes as Enantioselective Catalysts: Structure, Dynamics and Mechanistic Insight
Author(s) -
Di Bari Lorenzo,
Di Pietro Sebastiano,
Pescitelli Gennaro,
Tur Fernando,
Mansilla Javier,
Saá José M.
Publication year - 2010
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201001683
Subject(s) - lanthanide , isostructural , enantioselective synthesis , scandium , chemistry , catalysis , salt (chemistry) , ligand (biochemistry) , crystallography , alkali metal , crystal structure , paramagnetism , inorganic chemistry , organic chemistry , physics , ion , biochemistry , receptor , quantum mechanics
The ligand 3,3'‐bis(diethylaminomethyl)‐1,1'‐bi‐2‐naphthol (binolam) contains an arrayed Brønsted acid–Brønsted base (BABB) system, which is responsible for the original shape of its lanthanide compounds. The solution structure of Pr, Nd and Yb compounds is solved by means of paramagnetic NMR spectroscopy and it is demonstrated that they are substantially isostructural, but with a completely new fold compared to the apparently similar heterobimetallic systems based on 1,1'‐bis(2‐naphthol) (binol) and alkali cations. The aromatic nuclei lie in a region equatorial with respect to the C 3 symmetry axis, whereas the alkylamine chain stretches almost parallel to C 3 , above (and below) Ln 3+ . This is also found in the crystal structure of the binolamo–scandium complex. A detailed study of the proton‐exchange processes within the network of BABBs present in the complex is reported, which provides insight into the mechanism of the enantioselective Henry reaction promoted by these systems.