Two phosphaalkene radical cations with inverse spin density distributions

Abstract

Two phosphaalkene radical cations 1(•+) and 2(•+) have been reported. 1(•+) is stable in the solid state and has been structurally characterized. 2(•+) only remains persistent in solution. 1(•+) is described as a phosphorus-centered radical, while 2(•+) as a delocalized radical with little contribution from phosphorus.

Synthesis and Characterization of Cyclopentadithiophene Heterofulvenes: Design Tools for Light‐Activated Processes

“…EPR and DFT studies of stable radical anions based on fluoren‐9‐ylidene phosphanes, that is, a dibenzoheterofulvene, have shown that spin density largely resides on phosphorous . In contrast, stable radical cations have only been found for inverse polarized phosphaalkenes . The cathodic scans of our systems show an irreversible oxidation at 0.94 V for PA and 0.87 V for AsA with two additional features at around +0.5 and +0.35 V during the anodic scan direction, indicative of polymer deposition .…”

“…[17] In contrast, stable radicalc ations have only been found for inverse polarized phosphaalkenes. [18] The cathodic scans of our systems show an irreversible oxidation at 0.94 Vf or PA and0 .87 Vf or AsA with two additional features at around + 0.5 and + 0.35 V during the anodic scan direction, indicative of polymer deposition. [12] The gold-substituted complex PA-AuCl shows an irreversible reductiona ts low scan rates,w hich becomes quasi-reversible (E 1/2 = À1.56 V) at higher scan rates (n = 1Vs À1 )b esides an irreversible oxidationat0 .68 V.…”

Heavier pnictogens – treasures for optical electronic and reactivity tuning

“…12, 45). 47 By thienyl extension of the conjugated fluorenyl core, Orthaber and coworkers were able to spread the spin density towards the α-thienyl carbon atoms (46 •+ ), allowing for the cationic radical polymerisation of both arsa-and phosphaalkene derivatives (Fig. 12, P5).…”

Organophosphorus Compounds in Organic Electronics

“…In contrast, an inverse electron density upon oxidation of the fluorene‐derived phosphaalkene ( 63 ; Figure ) was evidenced by EPR spectroscopy. The drastic decrease in the 31 P coupling revealed that the spin density delocalizes over the fluorene core . Interestingly, fluorene‐based phosphaalkenes also form stable radical anions ( 64 .− ; Figure ) upon one‐electron reduction with Li(DME) and K(THF) to give discrete ions and ion pairs, respectively.…”

“…In contrast, an inverse electron density upon oxidation of the fluorene-derived phosphaalkene (63;F igure 12) was evidenced by EPR spectroscopy.T he drastic decrease in the 31 P coupling revealed that the spin density delocalizes over the fluorene core. [109] Interestingly,f luorene-based phosphaalkenes also form stable radical anions (64C À À ;F igure 12) upon one-electron reduction with Li(DME) and K(THF)t og ive discrete ions and ion pairs,r espectively.A ppreciable spin density is found on the Pc enter( 0.59),m uch highert han on the Ca tom of the double bond (0.11), which is consistent with ar esonance structure of an phosphinyl radicala nd an anionic (aromatic) fulvene core, also confirmed by EPR measurements (doublet with g = 2.0062). In contrastt ot he corresponding radical cation, two additional absorptions at about 500 and 580 nm are assigned to the HOMO(b)-LUMO(b)a nd the HOMO(a)-LUMO(a)t ransitions, respectively.…”