Insertion complexes of an organic molecule trapped in ion-pairs

Counterion‐Trapped‐Molecules: From High Polarity and Enriched IR Spectra to Induced Isomerization

“…The smaller transferred charge on the molecule in Li‐lad‐F compared to Li‐cub‐F could be related to the thinner separating molecule (with one C 4 “aperture” stretched). This interpretation may also apply to the analogous situation for Li−C 3 H 6 −F and Li−C 4 H 8 −Cl with almost identical charges of +0.96/0.95 e on Li and −0.91 e on F/Cl . In comparison, for other Li‐mol‐F systems the charges for mol=cyclohexane are close to those for the present ladderene case, or the molecule is slightly positive, at +0.10 e, for mol=adamantane, where Li is least charged at +0.81e …”

“…[8] Metastability was found for the LiÀ C 4 H 8 À Cl and LiÀ C 3 H 6 À F counterparts as well. [7,6] In the former system, D e = À 1.92 eV indicates a lower energy above the dissociation products compared to the present case, consistent with the shorter LiÀ Cl distance of 4.71 Å due to the thinner inserted molecule. However, for the latter system, D e = À 2.87 eV matches the present value for LiÀ C 8 H 8 À F, while the LiÀ F distance is still smaller at 4.35 Å.…”

“…The anionic complex stretches axially by about 0.5 Å, with both Li and F withdrawing a similar distance away from the molecule. This result is similar to Li−C 3 H 6 −F − and Li−C 4 H 8 −Cl − , although these systems stretch somewhat less and more (by about 0.4 and 0.7 Å), respectively, consistent with smaller inserted C 3 H 6 and with C 4 H 8 recovering its part‐folded shape, hence pushing Li and F farther apart. The potential barriers for Li or F to go around the molecule towards one another are significantly lower than for the neutral counterpart, at about 0.1 and 0.2 eV, respectively.…”

“…Metastability was found for the Li−C 4 H 8 −Cl and Li−C 3 H 6 −F counterparts as well . In the former system, D e =−1.92 eV indicates a lower energy above the dissociation products compared to the present case, consistent with the shorter Li−Cl distance of 4.71 Å due to the thinner inserted molecule.…”

“…The potential energy barriers stabilizing Li‐cub‐F are about 0.4 eV for either Li or F to go around the molecule and recombine with the other framing atom, producing cub‐LiF in both cases (Figure ). In particular, these barriers are about 0.1 to 0.2 eV higher than those for the analogous Li−C 4 H 8 −Cl and Li−C 3 H 6 −F, with the flattened cyclobutane in the former system resembling compressed cubane with half the carbon core. This result is consistent with a more rigid molecule, compared to C 4 H 8 part‐folding into a chair‐like structure upon its release from in‐between the counterions, and with a wider open “tetrapod” of CH bonds in cubane, compared to a “tripod” in cyclopropane, allowing Li and F to sink in deeper and experience stronger attraction.…”