A new inversion process at Group VA (Group 15) elements. Edge inversion through a planar T-shaped structure

Why edge inversion? Theoretical characterization of the bonding in the transition states for inversion in F n NH(3−n) and FnPH(3−n) (n = 0–3)

“…All of the molecules go through D 3h -like transition states, except for PF 3 and F 2 PH, which have T-shaped transition states, a fact first reported by Dixon and coworkers [4][5][6][7][8]. For all of the molecules with D 3h -like transition states, the bond distances are shorter than those in their ground states, a result of the increased s character in the N and P bond orbitals in the transition states.…”

“…This quasi-linear structure is also present in PF 3 , where the FPF axial angle is 176.0°and the angle between the axial and equatorial F atom is 88.0°. These two transition states are referred to as T-shaped transition states as first characterized by Dixon and coworkers [4][5][6][7][8] and are referred to as edge transition states in contrast to the transition states for the other six F n NH (3-n) and F n PH (3-n) molecules, which are referred to as vertex transition states. Table 1 The geometries, frequencies and total energies for the ground states (GS) of the F n NH (3-n) (n = 0-3) molecules from CCSD(T) calculations with the indicated basis sets Distances are in Å , angles in degrees, frequencies in cm -1 and energies in Hartrees Table 2 The geometries, frequencies and total energies for the inversion transition states (TS) of the F n NH (3-n) (n = 0-3) molecules from CCSD(T) calculations with the indicated basis sets Distances are in Å , angles in degrees, frequencies in cm -1 and energies in Hartrees.…”

“…Another hypervalent 10-P-3 compound, an intermediate, was discovered by Lochschmidt and Schmidpeter at approximately the same time [3]. Following up on this discovery, Dixon and co-workers [4][5][6][7][8] explored the structures of the transition states for inversion in phosphorus compounds. They performed calculations on PH 3 , FPH 2 , F 2 PH and PF 3 and found that F 2 PH and PF 3 have T-shaped transition states while FPH 2 and PH 3 have D 3h -like transition states.…”

The syntheses and structures of iron carbonyl adducts of tricoordinated hypervalent phosphorus compounds

“…The conversion of an intermolecularly formed ADPO anti dimer to the syn isomer could be accomplished if a single phosphorus were free to invert. The inversion of any of these phosphorus centers cannot occur by a traditional vertex inversion mechanism due to the electronegative substituents at phosphorus [31,33,351. The edge inversion process is electronically the most favored pathway in these systems [12,[31][32][33]351.…”

“…The inversion of any of these phosphorus centers cannot occur by a traditional vertex inversion mechanism due to the electronegative substituents at phosphorus [31,33,351. The edge inversion process is electronically the most favored pathway in these systems [12,[31][32][33]351. The strict geometric requirements of the edge inversion transition state make it difficult to accommodate in the dimer ring system due to ring strain and steric hindrance.…”