Search for a Parity-Violating Energy Difference between Enantiomers of a Chiral Iron Complex

Abstract

Mössbauer spectra for $l$ and $d$ enantiomers of the $\mathrm{Fe}\left(\mathrm{phen}{)}_3{\mathrm{Sb}}_2\right({\mathrm{C}}_4{\mathrm{H}}_2{\mathrm{O}}_6{)}_2̇8{\mathrm{H}}_2\mathrm{O}$ complex are reported. Four independent experiments show a small but reproducible energy shift of the Fe-Mössbauer spectra for the two enantiomers of $0.004\pm 0.002\mathrm{mm}/\sec$ ( $1.9\times {10}^{-10\mathrm{}}\mathrm{eV}$). This exceedingly small energy difference is comparable to that predicted by the parity-violating energy difference (PVED) using a $Z^{6.2}$ scaling law applied to low $Z$ ( $Z=6\mathrm{}$) molecules. Theoretical calculations suggest that the PVED for the $\mathrm{Fe}(\mathrm{phen}{)}_3^{2+}$ moiety should be smaller than this estimate, however, PVED effects of the chiral antimony tartrates are not taken into account.