Spectroscopic Identification of Diphosphene HPPH and Isomeric Diphosphinyldene PPH₂

Abstract

The simplest diphosphene HPPH and isomeric diphosphinyldene PPH2 features prototype phosphorus‐phosphorus multiple bonding properties that have been of long‐standing interest in main‐group chemistry. Herein, we report the observation of cis‐HPPH, trans‐HPPH, and PPH2 among the respective laser photolysis products of phosphine (PH3) and diphosphine (P2H4) in solid N2‐ and Ar‐matrices at 10 K. The identification of these P2H2 isomers with matrix‐isolation IR and UV/Vis spectroscopy is supported by D‐isotope labeling and the quantum chemical calculations at the CCSD(T)‐F12a/cc‐pVTZ‐F12 level using configuration‐selective vibrational configuration interaction theory (VCI). Bonding analyses suggest that the two conformers of HPPH contain standard PP double bonds, whereas, PPH2 resembles P2 in having partial PP triple bond due to the H2P←P π bonding interaction.

Phosphinidenes: Fundamental Properties and Reactivity

“…The high reactivity of PH is further examplified by its spontaneous dimerization of triplet PH at 10 K, yielding the simplest diphosphene HPPH in syn and anti conformations that can be interconverted upon selective UV-light irradiations. [17] Similar photochromic conformational rearrangements have been recently found for diphosphene transition metal complexes. [18] As the halogenated derivatives of PH, the diatomic molecules PF, PCl, and PBr are involved in the decomposition of the halogenated phosphorus-containing compounds.…”

“…Laser photolysis of matrix‐isolated HPN 2 at 266 nm mainly furnishes PH and N 2 with minor fragmentation to H and PN 2 . The high reactivity of PH is further examplified by its spontaneous dimerization of triplet PH at 10 K, yielding the simplest diphosphene HPPH in syn and anti conformations that can be interconverted upon selective UV‐light irradiations [17] . Similar photochromic conformational rearrangements have been recently found for diphosphene transition metal complexes [18]…”

“…Quite recently, ligand-free PPH 2 was identified among the 193 nm laser photolysis products of PH 3 in solid N 2 -and Armatrices at 10 K. [17] The reaction proceeds through the dimerization of the initially generated phosphinidene PH, followed by 1,2-H shift under the irradiation conditions (Scheme 1). As an alternative method, PPH 2 can be directly synthesized through the photolytic dehydrogenation of diphosphine P 2 H 4 in solid matrix (Scheme 9).…”

Trendbericht Anorganik 2024: Hauptgruppen‐ und Molekülchemie

“…Sie könnten wichtige astrochemische Zersetzungsprodukte von PH 3 sein und damit eine zentrale Rolle bei der interstellaren Bildung von Nukleinsäuren und Phospholipiden spielen. 28) Molekulare Hauptgruppenverbindungen finden in der Materialchemie zunehmend Anwendung. Ein Team um Chitnis synthetisierte Phospha-bicyclo[2.2.2]octan [(P NSi-Me 3 ) 2 (NMe) 6 ].…”

Diphosphene with a phosphineborane tether and its rhodium complex

“…Diphosphenes C with a PP bond in the molecules are also low-coordinate phosphorus compounds that captivated chemists early on. 5,6 The LUMO level of the PP π* orbital in diphosphenes is lower than that of the PC π* orbital in phosphaalkenes or phosphinines, 7 which should enhance the π-accepting character of the transition metals. We recently demonstrated that a gold complex of diphosphene with a 1,1′-binaphthyl group is an active catalyst for the intramolecular hydroarylation of aryl alkynyl ethers.…”