Capture of Phosphorus(I) and Arsenic(I) Moieties by a 1,2-Bis(arylimino)acenaphthene (Aryl-BIAN) Ligand. A Case of Intramolecular Charge Transfer

Abstract

The reaction of PCl3 with SnCl2 in THF solution, followed by treatment with dpp-BIAN (dpp = 2,6-i-Pr2C6H3), affords the phosphenium complex [(dpp-BIAN)P][SnCl5.THF]. The 31P chemical shift (delta 232.5) and the metrical parameters from a single-crystal X-ray diffraction study indicate that the oxidation state of phosphorus in this compound is +3. A similar conclusion was reached regarding the phosphorus oxidation state in [(dpp-BIAN)P][I3], which was prepared via the reaction of dpp-BIAN with PI3 in CH2Cl2 solution. The arsenium salt [(dpp-BIAN)As][SnCl5.THF] was prepared by treatment of AsCl3 with SnCl2 in THF solution, followed by the addition of dpp-BIAN. The X-ray crystal structure of this salt was determined, and the pattern of bond distances and angles indicates that arsenic is present in the +3 oxidation state.

Recent Developments in the Chemistry of N-Heterocyclic Phosphines

“…3.1.2 ), the group of Cowley was the first to describe a direct conversion of a -diimines into cationic heterocycles by means of a reaction that can be described as capture of a P(I) cation by diazabutadiene via [4 + 1] cycloaddition [31] (Scheme 4 ). The P(I) moiety is either generated by reduction of phosphorus trihalides with tin dichloride in the presence of the diimine [31] or, even more simply, by spontaneous disproportionation of phosphorus triiodide in the presence of the diimine [32] . The reaction is of particular value as it provides a straightforward access to annulated heterocyclic ring systems.…”

“…The reaction is of particular value as it provides a straightforward access to annulated heterocyclic ring systems. Thus, the tricyclic structure of 11 is readily assembled by addition of a P(I) moiety to an acenaphthene-diimine [31] , and the pyrido-annulated cationic NHP 12 is generated by action of appropriate pyridine-carbaldimines upon PI 3 [33] . In addition to cyclic phosphenium cations, homologous arsenium ions were also obtained [31] .…”

“…Of particularly high diagnostic value are 31 P NMR spectra where rather specific chemical shift ranges for heterocycles with different types of P-substituents can be observed. The largest chemical shifts occur for anionic and neutral 1,3,2-diazaphospholes (220-300 ppm) and 1,3,2-diazaphospholenium cations (210-200 ppm).…”

Ligand‐Stabilized Chalcogen Dications

“…[13a,b, 20,21] An indication of the extraordinary reactions that may be possible with these trapped monoatomic electrophiles is furnished by the report from Driess et al on the synthesis of the intriguing square-planar phosphonium cation P[Zr(H)Cp 2 ] 4 + , where the dicoordinate P-centred cation [(Me 2 N) 3 P] 2 P + was used as a source of "P + " in the reaction with [Cp 2 Zr(H)Cl]. [22] To date, the reactions of the novel chalcogenium dications in salts of type 1 and 2 have been limited to a preliminary report of the facile extrusion of the chalcogen from the heterocyclic ring by phosphines to give SPR 3 .…”

Synthesis and characterization of a 2-chloro-1,3,2-diaza-phospholidine-4,5-diimine

“…5,6,7 Cations 4 have alternatively been accessed via a [1+4]-cycloaddition route starting from a diazabutadiene and a transient P(I) fragment generated via disproportionation of PI 3 , or via reduction of PCl 3 with SnCl 2 , respectively. 10 In view of this approach we became interested in the synthesis of derivatives 7 featuring both a five-membered phosphorus-nitrogen heterocycle and a diazabutadiene moiety. Molecules of this type have not only a large potential as bridging ligands in coordination chemistry, but offer also a prospect to generate functional phosphenium ions via P-Cl bond heterolysis, or prepare novel fused heterocyclic systems via subsequent [1+4]-cycloadditions.…”