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Complexes Between 1,1′‐Binaphthyl‐2,2′‐Dicarboxylic Acid and Pyrazoles: A Case of Manual Sorting of Conglomerate Crystals (Triage)
Author(s) -
Hager Orm,
LlamasSaiz Antonio L.,
FocesFoces Concepción,
Claramunt Rosa M.,
López Concepción,
Elguero José
Publication year - 1999
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/(sici)1522-2675(19991215)82:12<2213::aid-hlca2213>3.0.co;2-r
Subject(s) - chemistry , crystallization , enantiomer , crystallography , absolute configuration , crystal (programming language) , resolution (logic) , pyrazole , stereochemistry , organic chemistry , artificial intelligence , programming language , computer science
The crystal and molecular structure of two salts, I and III , and one molecular complex, II , formed by combining 1,1′‐binaphthyl‐2,2′‐dicarboxylic acid (BNDA) with pyrazole ( 3 ) and 3,5‐dimethylpyrazole ( 4 ) has been determined by X‐ray crystallography. The most striking feature is the spontaneous resolution of the racemic BNDA host by co‐crystallization with 4 , an achiral guest, to form the salt III . The absolute configuration of three manually selected crystals of III have been established by crystallographic methods. The two crystals formed by the ( P )‐enantiomer display a negative Cotton effect. 13 C‐CPMAS‐NMR Spectroscopy has been used to compare the compounds obtained by crystallization with those prepared by mechanical grinding.