METALLOCENOPHANES .6. 5,12-METHANO[2.2.2]PARACYCLOPHANE - A NEW LIGAND FOR PI-COMPLEXATION IN A CAVITY - IMPROVED SYNTHESIS AND THE CHARACTERIZATION OF ITS SILVER(I) PERCHLORATE COMPLEX
Fr. Heirtzler et al., METALLOCENOPHANES .6. 5,12-METHANO[2.2.2]PARACYCLOPHANE - A NEW LIGAND FOR PI-COMPLEXATION IN A CAVITY - IMPROVED SYNTHESIS AND THE CHARACTERIZATION OF ITS SILVER(I) PERCHLORATE COMPLEX, Journal of organic chemistry, 58(10), 1993, pp. 2781-2784
The consequences of a bridging methylene group in 1, i.e. as in 2, on
the geometry and ability to complex Ag(I) were studied. Compound 2 was
prepared in three steps and 36% overall yield from 1 in a new procedu
re and characterized through X-ray crystallography. The X-ray crystal
structure of its endo complex (3) with AgClO4 shows three independent
molecules in the crystal lattice. The geometry of the ligand in 3 is l
ike that in 2. Ag is 2.48-3.00 angstrom from the nearest Ar-C, is 0.13
-0.31 angstrom outside of the cavity of 2, and binds nearly symmetrica
lly across the C(5)-C)6), C(11)-C(12), and C(23)-C(24) bonds. Compound
2 is shown to be a weaker complexing agent for Ag(I) than [2.2.2]-par
acyclophane. Practical and theoretical ramifications of the bonding mo
de are discussed.