Parity violation effects in helical osmocene: theoretical analysis and experimental prospects

Abstract

We present a computational investigation of the parity-violating (PV) contributions to the vibrational transitions and nuclear magnetic resonance shieldings of helical osmocene. A number of promising transitions within the spectral window of currently available sub-Hz metrology-grade lasers are identified, exhibiting high intensities and parity violation shifts of up to 7 Hz. We discuss the prospects for the synthesis of this compound and for subsequent ultra-precise mid-IR spectroscopy towards the first detection of parity violation in a chiral molecule.

Figures (9)

• Figure 1: Helical metalocene structure (X = Fe/Ru/Os) with 10 connected carbon atoms ($\eta$-10 complex).
• Figure 2: Minus (M) and plus (P) enantiomers of helical osmocene and corresponding PV contributions to the vibrational transitions.
• Figure 3: Correlation between PV frequency shifts in helical osmocene calculated on two different levels of theory -- the higher level uses dyall.v3z basis set for Os in the $E^\text{M,PV}$ calculations and potential $V(q)$ calculated in Q-Chem; the lower level uses dyall.v2z basis set for Os in the $E^\text{M,PV}$ calculations and potential $V(q)$ from the same DIRAC calculations. In both cases, the v2z basis set was used for the carbons and the hydrogens. Red line shows the ideal linear correlation.
• Figure 4: PV Frequency shifts of the recommended modes calculated using different DFT functionals and Hartree--Fock. Red dots represent the CAM-B3LYP* values, while black bars represent the range of frequency shifts calculated using all methods (based on the values in Table S3 in ESI$^\dag$).
• Figure 5: Absolute values of the PV frequency shifts of the vibrational transitions of helical osmocene plotted against the total metal-carbon displacement. The vibrations selected as promising for measurements (see Table \ref{['tab:recommendation']}) are marked in red.