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Ammonium, Alkylammonium, and Amino Acid Complexes of a Hexacopper Fluoro‐Metallacrown Cavitand
Author(s) -
Jones Leigh F.,
Barrett Simon A.,
Kilner Colin A.,
Halcrow Malcolm A.
Publication year - 2007
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.200701318
Subject(s) - chemistry , medicinal chemistry , cavitand , yield (engineering) , hydrogen bond , molecule , alanine , stereochemistry , ammonium , nuclear magnetic resonance spectroscopy , ion , crystallography , amino acid , crystal structure , supramolecular chemistry , organic chemistry , biochemistry , materials science , metallurgy
Reaction of CuF 2 with one equivalent of 3{5}‐(pyrid‐2‐yl)‐5{3}‐( tert butyl)pyrazole (HL) and excess NH 4 OH in MeOH affords crystalline [NH 4 {Cu(μ‐F)(μ‐L)} 6 (CH 2 Cl 2 ) 2 ]HF 2 in moderate yield. This compound contains the 12‐MC‐6 metallacrown [{Cu(μ‐F)(μ‐L)} 6 ] ( 1 ) with a NH 4 + ion at its center, and CH 2 Cl 2 molecules complexed in bowl‐shaped cavities above and below the Cu 6 F 6 ring. Similar reactions using the bases MeNH 2 , glycine, l‐ alanine or β‐alanine afforded solvated crystals of [ 1 (H 3 NMe) 2 ]Cl 2 , [ 1 (gly) 2 ], [ 1 ( l‐ ala) 2 ], and [ 1 (β‐ala) 2 ], respectively. The metallacrown 1 in these products contains methylammonium and zwitterionic amino‐acid guests in its two bowl‐shaped cavities; each of the amino acids hydrogen‐bonds to three F atoms. A related reaction using 1,6‐diaminohexane resulted in fixation of CO 2 from the air to give solvated [ 1 (H 3 NC 6 H 12 NHCO 2 ) 2 ], again with a zwitterionic guest. NMR, ESI‐MS and UV/vis measurements suggest that the metallacrown 1 retains its integrity in several organic solvents, although it is unclear to what extent guest binding takes place in solution.