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Pyrazole Complexes as Anion Receptors
Author(s) -
Nieto Sonia,
Pérez Julio,
Riera Lucía,
Riera Víctor,
Miguel Daniel
Publication year - 2006
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.200500913
Subject(s) - chemistry , pyrazole , adduct , moiety , protonation , perrhenate , medicinal chemistry , iodide , bromide , ligand (biochemistry) , crystallography , inorganic chemistry , stereochemistry , ion , organic chemistry , receptor , biochemistry
The behavior of the receptors [Re(CO) 3 (Hdmpz) 3 ]BAr′ 4 (Hdmpz=3,5‐dimethylpyrazole) ( 1 ) and [Re(CO) 3 (H t Bupz) 3 ]BAr′ 4 (H t Bupz=3(5)‐ tert ‐butylpyrazole) ( 2 ; Ar′=3,5‐bis(trifluoromethyl)phenyl) toward the anions fluoride, chloride, bromide, iodide, hydrogensulfate, dihydrogenphosphate, nitrate, and perrhenate was studied in CD 3 CN solution. In most cases, the receptors were stable. Anion exchange was fast, and binding constants were calculated from the NMR titration profiles. The structure of the adduct [Re(CO) 3 (H t Bupz) 3 ]⋅NO 3 ( 3 ) was determined by X‐ray diffraction. Two pyrazole moieties are hydrogen‐bonded to one nitrate oxygen atom, and the third pyrazole moiety is hydrogen‐bonded to an oxygen atom of an adjacent nitrate, leading to infinite chains. The structure of the adduct [Re(CO) 3 (Hdmpz) 3 ]BAr′ 4 ⋅acetone ( 4 ), also determined by X‐ray diffraction, showed a similar interaction of two pyrazole NH groups with the acetone oxygen atom. F − and H 2 PO 4 − deprotonate the receptors, and HSO 4 − decomposed 1 . The structure of one of the decomposition products ( 5 ), determined by X‐ray diffraction, is consistent with pyrazole protonation and substitution by sulfate.