Silicon-Bridged Metacyclophanes as Parent Compounds of Silacalix[ n ]arenes. Synthesis, Structures, and Conformational Analysis by Semiempirical MO Calculations
1999; American Chemical Society; Volume: 18; Issue: 8 Linguagem: Inglês
10.1021/om980848k
ISSN1520-6041
AutoresMasaru Yoshida, Midori Goto, Fusae Nakanishi,
Tópico(s)Molecular Sensors and Ion Detection
ResumoThis paper includes the preparation of the unsubstituted silicon-bridged metacyclophanes as parent compounds of silacalix[n]arenes (n = 3, 4). A one-pot reaction gave the two different organosilicon macrocyclics, concomitantly. The structures of the metacyclophanes were unequivocally determined by X-ray crystallography. As a result, it was shown that trisila[1.1.1]metacyclophane (trisilacalix[3]arene, 1) and tetrasila[1.1.1.1]metacyclophane (tetrasilacalix[4]arene, 2) adopted a saddle structure and a 1,2-alternate structure, respectively. The conformations of these silacalixarenes were also analyzed by semiempirical PM3 calculations, which indicated that the conformations of the silacalixarenes in the crystal did not represent an energy minimum. A completely C3 symmetric cone structure of 1 and a 1,3-alternate structure of 2 were estimated as the most stable conformations, respectively. In addition, a π-complex formation between the silacalixarenes and silver cation was observed by FAB mass spectrometry. This is the first observation of π-complexation of a metal ion by a [1.1.1]metacyclophane derivative.
Referência(s)