Investigations into the Photophysical and Electronic Properties of Pnictoles and Their Pnictenium Counterparts

Abstract

The reaction of phosphole/arsole starting materials with a series of halide abstraction reagents afforded their respective phosphenium/arsenium complexes. UV-vis absorption and luminescence studies on these cations showed interesting emission profiles, which was found to be dependent upon counterion choice. The addition of a reductant to the phosphole reagent garnered a dimeric species with a central P-P bond, which when heated was found to undergo homolytic bond cleavage to produce an 11π radical complex. Electron paramagnetic resonance (EPR), supported by density functional theory (DFT) calculations, was used to characterize this radical species.

Arsenic Catalysis: Hydroboration of Aldehydes Using a Benzo‐Fused Diaza‐benzyloxy‐arsole

“…Analysis of the solid‐state structures of 3 and 4 revealed that both compounds crystallize in the monoclinic space group P 2 1 / c . For 3 two molecules were present in the asymmetric unit, with metrics of the C 2 N 2 As ring similar to that previously reported for 1 . The As−O bond length was found to be 1.82(2) Å, similar to those reported previously for As III −O bonds, and an As‐O‐C interior bond angle of 119.06(12)–120.79(12)°.…”

Functionalization of Bis‐Diazaphospholene P–P Bonds with Diverse Electrophiles

“…Bis‐diazaphospholene 2 was shown to be a source of persistent 7 pi radical 5 , however the solution concentration of these radicals is typically low relative to that of dimer 2 at ambient temperature . We found that 2 could be accessed in high yield and purity via reductive coupling of readily accessible 3‐Br with magnesium turnings in THF . An alternate synthesis of bis‐diazaphospholene 2 involves a photochemical dehydrocoupling, via the ultraviolet irradiation of hydride 3‐H with concomitant release of hydrogen, as reported by Nyulászi, Gudat and co‐workers (Equation 2, Scheme ) .…”

Structure–property-reactivity studies on dithiaphospholes

“…This reduced bond order can be explained by hyperconjugation between the π electrons in the C 2 S 2 unit and the σ*(P-X) orbital, in turn weakening the P-X bond, which is consistent with observations we have previously reported on related diaza-phosphole compounds. 29 In addition, NBO analysis showed significant polarisation in this bond, with a natural charge of +0.53 on the P heteroatom, and −0.33 on the Cl atom; the S atoms exhibit natural charges of +0.06. Comparing the results of 1a to 1b and 1c, a reduction in the polarisation of the P-X bond was found to be accompanied by a small increase in bond order.…”