We re-examined the existence of planar tetracoordinate F (ptF) atoms, which was proposed recently by using highlevel ab initio methods such as coupled-cluster singles and doubles with perturbative triples (CCSD(T)) with large basis sets. Our calculations indicate that the planar structures of FIn 4 + (D 4h ), FTl 4 + (D 4h ), FGaIn 3 + (C 2V ), FIn 2 Tl 2 + (D 2h ), FIn 3 Tl + (C 2V ), and FInTl 3 + (C 2V ) are not the minimum energy states; by contrast, they are transition states. Density functional theory calculations overestimate the size of the cavity formed by the four peripheral atoms, leading to erroneous conclusions regarding the existence of ptF atoms. Our analysis suggests that the preference for non-planar structures in the six cations studied is not due to the pseudo Jahn−Teller effect. Additionally, spin−orbit coupling does not alter the main conclusion that the ptF atom does not exist. If sufficiently large cavity formation by group 13 elements to accommodate the central F − ion is guaranteed, then the existence of ptF atoms is plausible.

Discovery of a new oxidation state for an element expands its chemistry. A high oxidation state, such as +7, is rare for sp-block elements except for halogens. In this study, we determined that Te can attain a +7 oxidation state through the existence of a distorted octahedron (DOH) structure of TeCl6+ based on coupled cluster singles and doubles with perturbative triples calculations. We propose a new type of isomerization that resembles pseudorotation. The octahedron structure of TeF6+ bearing one elongated axial bond isomerizes to a DOH via an associated pseudorotation.

Time-resolved X-ray liquidography (TRXL) has emerged as a powerful technique for studying the structural dynamics of small molecules and macromolecules in liquid solutions. However, TRXL has limited sensitivity for small molecules containing light atoms only, whose signal has lower contrast compared with the signal from solvent molecules. Here, we present an alternative approach to bypass this limitation by detecting the change in solvent temperature resulting from a photoinduced reaction. Specifically, we analyzed the heat dynamics of TRXL data obtained from p-hydroxyphenacyl diethyl phosphate (HPDP). This analysis enabled us to experimentally determine the number of intermediates and their respective enthalpy changes, which can be compared to theoretical enthalpies to identify the intermediates. This work demonstrates that TRXL can be used to uncover the kinetics and reaction pathways for small molecules without heavy atoms even if the scattering signal from the solute molecules is buried under the strong solvent scattering signal.

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