Salts of 12-alkyl and 12-phenyl derivatives of the CB 11 H 12 - anion are prepared in 50−60% yields from the 12-iodo-CB 11 H 11 - anion by Pd-catalyzed cross-coupling with Grignard reagents. The tropylium ylide 12-C 7 H 6 + -CB 11 H 11 - is made in 54% yield by reaction of C 7 H 7 + with CB 11 H 12 - . Its ground-state dipole moment is 11.25 ± 0.1 D and its first hyperpolarizability is β = 236 × 10 -30 esu at 1064 nm, as determined by hyper-Rayleigh scattering measurement. This value is ten times that of p -nitroaniline and is surprisingly large considering that the compound is colorless.
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Grüner et al. (1999) studied this question.