Second-Order Jahn−Teller Distortions in Group 17 Fluorides EF3 (E = Cl, Br, I, and At). Large Relativistic Bond Angle Changes in AtF3

摘要: Group 17 element fluorides EF3 (E = Cl, Br, I) are well-known to undergo second-order Jahn−Teller symmetry breaking toward a T-shaped C2v arrangement mainly due a1‘HOMO ⊗ e‘LUMO mixing at the expected symmetric trigonal planar D3h state. For heavy elements, a1‘ HOMO is relativistically stabilized because of large s-orbital participation. Hence, relativistic effects diminish term. This results in change Feq−E−Fax bonding angle αeR − αeNR 5.5° case AtF3 and causes an anomaly bond behavior down group compounds, α(ClF3) > α(BrF3) α(AtF3) α(IF3). Furthermore, difference between distorted structure only 10 kJ/mol coupled cluster level theory, indicating that measured Feq−At−Fax αe will be very sensitive upon temperature applied gas phase diffraction studies. Vibrational frequencies predicted for all EF3. As a...