Preparation and Characterization of Phenyl Phosphine Diselenide – The Monomeric Form of Woollins' Reagent

Abstract

We report the preparation, matrix‐isolation, and IR and UV/Vis spectroscopic characterization of phenyl phosphine diselenide, thus providing the first experimental evidence of the monomeric form of Woollins' reagent. Phenyl phosphine diselenide was prepared by thermal dissociation of Woollins' reagent and was identified by matching its spectroscopic data with density functional theory [B3LYP‐D3/6‐311++G(3df,3pd)] computations. The title compound proved to be highly photolabile and irradiation with light at λ = 334 nm results in the formation of hitherto unknown phenyldiselenyl phosphirane. Upon λ = 465 nm irradiation it rearranges back to phenyl phosphine diselenide.

Isolation and Characterization of the Free Phenylphosphinidene Chalcogenides C6H5P=O and C6H5P=S, the Phosphorous Analogues of Nitrosobenzene and Thionitrosobenzene

“…Recently, we reported the synthesis of previously elusive phenyldioxophosphorane ( 6 , PhPO 2 ), the phosphorus analogue of nitrobenzene, under matrix‐isolation conditions through the reaction of triplet phenylphosphinidene ( 5 ) with triplet molecular oxygen ( 3 P‐O 2 ) . The heavier congeners of 7 , namely (4‐methoxy)phenyl phosphine disulphide ( 6 ) and phenyl phosphine diselenide ( 8 ) (the monomeric forms of Lawesson's and Woollins’ reagents, respectively), have been isolated and characterized spectroscopically as well (Scheme C). Following our studies on the synthesis and reactivity of transient organophosphorus species including PhP, PhPO 2 , PhPCO, PhPS 2 , and PhPSe 2 , we report herein the first spectroscopic evidence of hitherto unknown “free” (that is, uncomplexed) phenylphosphinidene oxide Ph−P=O ( 1 ) and phenylphosphinidene sulfide Ph−P=S ( 2 ) by means of IR and UV/Vis spectroscopy (Scheme A).…”

Isolation and Characterization of the Free Phenylphosphinidene Chalcogenides C6H5P=O and C6H5P=S, the Phosphorous Analogues of Nitrosobenzene and Thionitrosobenzene

“…The heavier congeners of 7 , namely (4‐methoxy)phenyl phosphine disulphide ( 6 ) and phenyl phosphine diselenide ( 8 ) (the monomeric forms of Lawesson's and Woollins’ reagents, respectively), have been isolated and characterized spectroscopically as well (Scheme C). Following our studies on the synthesis and reactivity of transient organophosphorus species including PhP, PhPO 2 , PhPCO, PhPS 2 , and PhPSe 2 , we report herein the first spectroscopic evidence of hitherto unknown “free” (that is, uncomplexed) phenylphosphinidene oxide Ph−P=O ( 1 ) and phenylphosphinidene sulfide Ph−P=S ( 2 ) by means of IR and UV/Vis spectroscopy (Scheme A).…”

“…Computational analysis using time‐dependent density functional theory (TD‐B3LYP/6–311++G(3df,3pd)) of the excitations of 1 exhibit a strong transition at 284 nm ( f =0.222) and two weak transitions at 314 nm ( f =0.011) and 474 nm ( f =0.004) in good agreement with the experimentally observed UV/Vis spectrum (Figure ). Likewise, in our earlier studies on reactive organophosphorus species, the inspection of the molecular orbitals of 1 reveals that the weak absorption band in the visible region at 460 nm corresponds an n→π* transition, while the strong band at 277 nm is a π→π* transition.…”

History and Future of Dative Bonds

“…As expected, we believe that the DB form is more faithful to the bond origin and physical properties. It is worth mentioning that the equilibrium (or lack thereof) between triangular and angular Ch‐Pn‐Ch substituents (Ch=O, S or Se, Pn=N or P) has already been studied, and obeys similar rules.…”