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Mixed Aggregates of the Dilithiated Koga Tetraamine: NMR Spectroscopic and Computational Studies
Author(s) -
Ma Yun,
Mack Kyle A.,
Liang Jun,
Keresztes Ivan,
Collum David B.,
Zakarian Armen
Publication year - 2016
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201605199
Subject(s) - chemistry , lithium (medication) , dilithium , laddering , density functional theory , halide , computational chemistry , isostructural , organic chemistry , crystal structure , ion , medicine , finance , deprotonation , economics , endocrinology
A combination of 1 H, 6 Li, 13 C, and 15 N NMR spectroscopies and density functional theory computations explores the formation of mixed aggregates by a dilithium salt of a C 2 ‐symmetric chiral tetraamine (Koga's base). Lithium halides, acetylides, alkoxides, and monoalkylamides form isostructural trilithiated mixed aggregates with few exceptions. 6 Li– 13 C and 6 Li– 15 N couplings reveal heretofore undetected transannular contacts (laddering) with lithium acetylides and lithium monoalkylamides. Marked temperature‐dependent 15 N chemical shifts seem to be associated with this laddering. Computational studies shed light on the general structures of the aggregates, their penchant for laddering, and the stereochemical consequences of aggregation.