Chirality Induced in Tetraethyllead through Noncovalent Interactions with a Chiral Tag

Weakly bound complexes containing lead (Pb) were studied in a supersonic jet using broadband chirped-pulse Fourier transform microwave (CP-FTMW) spectroscopy, complemented with quantum-chemical calculations. These complexes were formed from a vapor mixture of tetraethyllead (TEL) and 2-(trifluoromethyl)oxirane (TFO), diluted in a Ne carrier gas. Theoretical isomer searches reveal 75 nearly isoenergetic isomers of the TEL-TFO dimer, all within an energy range of 1.0 kJ/mol. Rotational spectroscopy has unambiguously identified the global-minimum configuration in the ground vibrational state, including its three singly substituted ^206/207/208Pb isotopologues. This assignment is further supported by the observation of the TEL-TFO-Ne trimer, which gives rise to six doubly substituted ^206/207/208Pb-^20/22Ne isotopologues in their natural abundance. The experimental data provides a valuable benchmark for assessing modern quantum-chemical methods, particularly in the treatment of relativistic effects of heavy nuclei along with noncovalent interactions. Additionally, as heavy-atom-containing chiral complexes, parity-violating effects were calculated for the TEL-TFO dimer at various levels of theory, shedding light on parity nonconservation in weakly bound complexes involving heavy nuclei.