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The Relation between Ion Pair Structures and Reactivities of Lithium Cuprates
Author(s) -
John Michael,
Auel Carsten,
Behrens Christoph,
Marsch Michael,
Harms Klaus,
Bosold Ferdinand,
Gschwind Ruth M.,
Rajamohanan Pattuparambil R.,
Boche Gernot
Publication year - 2000
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 - 10.1002/1521-3765(20000818)6:16<3060::aid-chem3060>3.0.co;2-m
Subject(s) - diethyl ether , chemistry , lithium (medication) , reactivity (psychology) , solvent , ether , ion , inorganic chemistry , cuprate , crown ether , crystallography , computational chemistry , medicinal chemistry , organic chemistry , materials science , medicine , alternative medicine , optoelectronics , pathology , doping , endocrinology
From Li + well‐solvating solvents or complex ligands such as THF, [12]crown‐4, amines etc., lithium cuprates R 2 CuLi( . LiX) crystallise in a solvent‐separated ion pair (SSIP) structural type (e.g. 10 ). In contrast, solvents with little donor qualities for Li + such as diethyl ether or dimethyl sulfide lead to solid‐state structures of the contact ion pair (CIP) type (e.g. 11 ). 1 H, 6 Li HOESY NMR investigations in solutions of R 2 CuLi( . LiX) ( 15, 16 ) are in agreement with these findings: in THF the SSIP 18 is strongly favoured in the equilibrium with the CIP 17 , and in diethyl ether one observes essentially only the CIP 17 . Salts LiX (X=CN, Cl, Br, I, SPh) have only a minor effect on the ion pair equilibrium. These structural investigations correspond perfectly with Bertz's logarithmic reactivity profiles (LRPs) of reactions of R 2 CuLi with enones in diethyl ether and THF: the faster reaction in diethyl ether is due to the predominance of the CIP 17 in this solvent, which is the reacting species; in THF only little CIP 17 is present in a fast equilibrium with the SSIP 18 . A kinetic analysis of the LRPs quantifies these findings. Recent quantum‐chemical studies are also in agreement with the CIP 17 being the reacting species. Thus a uniform picture of structure and reactivity of lithium cuprates emerges.