Application of photoelectron spectroscopy to molecular properties. Part 34. Phosphaethene. Synthesis by vacuum gas-solid reaction (VGSR) and characterization by photoelectron spectroscopy

Abstract

Phosphaethene, the unstable parent compound in the phosphaalkenes series, has been thoroughly investigated using theoretical calculations. For the first time, its electronic structure is evidenced from its photoelectron spectrum. The P E spectra of phosphaethene and 1 -phosphapropene, generated in the gas phase by the respective vacuum dehydrochlorination of chloromethylphosphine and I-chloroethylphosphine, have been recorded in situ by the use of a vacuum device directly coupled to the spectrophotometer. T h e vertical rW and np ionization energies are observed respectively a t 10.30 and 10.70 eV for phosphaethene and a t 9.75 and 10.35 eV for I-phosphapropene. The band's characterizations are discussed through correlations with the corresponding imines and with substituted phosphaalkenes and are confirmed by a b initio theoretical calculations.T h e results indicate a rather significant energetic separation between the two first rWc and np ionic states.

Phospha‐Organic Chemistry: Panorama and Perspectives

“…[29] The "phospha-Peterson" reaction constitutes a third reliable route. An example is given in Equation (5). [30] For other examples, see ref.…”

“…(25)]. [59] The analogy between C¼C and P¼C bonds is completed by the participation of P¼C bonds in ene reactions, [60] [1,5], [61] and [3,3] sigmatropic shifts, [62] as well as 4 p [63] and 6 p electrocyclizations. [64] Finally, numerous conjugated or cumulated phosphapolyenes and phosphaketenes show chemistry which quite nicely parallels that of their all-carbon analogues.…”

“…[149a] From an electronic standpoint, these [RPÀM(CO) 5 ] complexes are quite different from the nucleophilic phosphinidenes described in Section 5.2. The ground states of [M(CO) 5 ] are singlets, [150] with singlet-triplet separation being approximately 33.7 kcal mol [150b] Thus, combining the triplet ground states of phosphinidenes with the triplet excited states of [M(CO) 5 ] costs more in energy than combining the singlet excited states of phosphinidenes with the singlet ground states of [M(CO) 5 ], especially for amino-phosphinidenes.…”

“…The ground states of [M(CO) 5 ] are singlets, [150] with singlet-triplet separation being approximately 33.7 kcal mol [150b] Thus, combining the triplet ground states of phosphinidenes with the triplet excited states of [M(CO) 5 ] costs more in energy than combining the singlet excited states of phosphinidenes with the singlet ground states of [M(CO) 5 ], especially for amino-phosphinidenes. The calculated tripletsinglet separations for RP, [151] the PÀW bond lengths in the corresponding [RPÀW(CO) 5 ] complexes, and the charges at phosphorus in these complexes [152,153] are given in Table 2.…”

“…The ground states of [M(CO) 5 ] are singlets, [150] with singlet-triplet separation being approximately 33.7 kcal mol [150b] Thus, combining the triplet ground states of phosphinidenes with the triplet excited states of [M(CO) 5 ] costs more in energy than combining the singlet excited states of phosphinidenes with the singlet ground states of [M(CO) 5 ], especially for amino-phosphinidenes. The calculated tripletsinglet separations for RP, [151] the PÀW bond lengths in the corresponding [RPÀW(CO) 5 ] complexes, and the charges at phosphorus in these complexes [152,153] are given in Table 2. When the calculated PÀW bond lengths are compared with the experimental values found for P¼W (2.349(5) [135] ) and PW bonds (2.169(1) [136] ), it is quite clear that [RPÀ 5 Cr¼PH] using an electron localizing function (ELF) analysis led to the same conclusions: a Ti¼P double bond and negative charge at the phosphorus center in the former, a CrÀP single bond and positive charge at phosphorus in the latter.…”