A Boryl‐Substituted Diphosphene: Synthesis, Structure, and Reaction with n‐Butyllithium To Form a Stabilized Adduct by pπ‐pπ Interaction

Abstract

A boryl-substituted diphosphene was synthesized through the nucleophilic borylation of PCl3 with a borylzinc reagent, followed by a reduction with Mg. A combined analysis of the resulting diboryldiphosphene by single-crystal X-ray diffraction, DFT calculations, and UV/Vis spectroscopy revealed a σ-electron-donating effect for the boryl substituent that was slightly weaker than that of the 2,4,6-tri-tert-butylphenyl (Mes*) ligand. The reaction of this diboryldiphosphene with (n) BuLi afforded a boryl-substituted phosphinophosphide that was, in comparison with the thermally unstable Mes*-substituted diaryldiphosphene, stabilized by a π-electron-accepting effect of the boryl substituent.

London Dispersion Interactions in Pnictogen Cations [ECl2]+ and [E=E]2+ (E=P, As, Sb) Supported by Anionic N‐Heterocyclic Carbenes

“…The P−P bond length in 5 is 2.0530(5) Å, which falls in the range reported for diphosphenes with bulky aryl substituents, and is also consistent with the distances reported for other NHC‐supported phosphorus‐phosphorus double bonds, for example, 2.0826(12) Å in V , 2.0450(11) Å in [(IDipp)P 2 (IMes)] 2+ , 2.0611(7) Å in VII , 2.038(1) Å in VIII , and 2.0655(17) Å in IX (Figure ) . The As−As and Sb−Sb bond lengths of 2.2882(8) Å in 6 and 2.6632(3) Å in 7 are also in good agreement with known diarsene and distibene compounds.…”

“…It is also in excellent agreement with the chemical shift of +452 ppm (in CD 3 CN) reported for [(IDipp) 2 P 2 ] 2+ ( V , as OTf salt); the GaCl 4 salt containing the heteroleptic congener [(IDipp)P 2 (IMes)] 2+ produced two signals in the same range at +440.1 and +438.5 ppm (in CD 2 Cl 2 ) with 1 J PP =543 Hz) . The boryl‐substituted diphosphene exhibits a resonance at even lower field (+605 ppm in C 6 D 6 ) …”

“…These cationic diphosphenes adopt intermediate positions between neutral and dicationic diphosphenes such as I and V . Another important example is the boryl‐substituted neutral diphosphene IX , which is electronically and structurally closely related to the dication V …”

Isolation and Characterization of Radical Anions Derived from a Boryl‐Substituted Diphosphene

“…[11] Thec hemical oneelectron reduction of 1 with KC 8 in the presence or absence of [2.2.2]cryptand in THF at À30 8 8Cg enerated purple crystalline solids of the radical anions [1C] À [K(THF) 2 ] + and [1C] À [K(cryptand)] + in 60 %a nd 69 %y ield, respectively (Scheme 2), and these products were structurally characterized by single-crystal X-ray diffraction ( Figure 2). [11] Thec hemical oneelectron reduction of 1 with KC 8 in the presence or absence of [2.2.2]cryptand in THF at À30 8 8Cg enerated purple crystalline solids of the radical anions [1C] À [K(THF) 2 ] + and [1C] À [K(cryptand)] + in 60 %a nd 69 %y ield, respectively (Scheme 2), and these products were structurally characterized by single-crystal X-ray diffraction ( Figure 2).…”

A Tale of Two Elements: The Lewis Acidity/Basicity Umpolung of Boron and Phosphorus

“…have reported the synthesis of a boryl‐phosphine via reactions of the boryl lithium species with chlorophosphines,(see 13 , Scheme ) while Yamashita et al. described the synthesis of a diboryldiphosphene 14 , and most recently, the generation of the corresponding P‐based radicals …”