The controlled activation of white phosphorus, P₄, provides a key entry point into many aspects of polyphosphorus chemistry. Herein, the reaction of cyclo-diphosphadiazane derivative (DmpNPCl)₂ (3a; Dmp = 2,6-dimethylphenyl) and P₄ in the presence of GaCl₃ as Lewis acid for the targeted synthesis of mono- and dicationic phosphorus-rich cage compounds [(DmpNP)₂(P₄)Cl][GaCl₄] (8a[GaCl₄]) and [(DmpNP)₂(P₄)₂][Ga₂Cl₇]₂ (9a[Ga₂Cl₇]₂) is reported. Depending on the reaction conditions, formation of these types of cages, which are similar to those of the known cations [(DippNP)₂(P₄)Cl]⁺ (8b⁺) and [(DippNP)₂(P₄)₂]²⁺ (9b²⁺; Dipp = 2,6-diisopropylphenyl) is observed. However, due to the reduced steric requirements of the Dmp compared to the Dipp group, an interconversion process of the P₂N₂ framework of cyclo-dichlorodiphosphadiazane 3a with the cyclo-trichlorotriphosphatriazane 5a is observed, which leads also to the formation of mono- and dicationic derivatives [(DmpNP)₃(P₄)Cl₂]⁺ (10a⁺) and [(DmpNP)₃(P₄)₂Cl]²⁺ (11a²⁺) via cyclo-triphosphatriazenium cation [(DmpNP)₃Cl₂]⁺ (4a⁺).

The reaction of the bis(imidazoliumyl)-substituted P^I cation [(2-Im^Dipp)P(4-Im^Dipp)]⁺ (10⁺) (2-Im=imidazolium-2-yl; 4-Im=imidazolium-4-yl; Dipp=2,6-di-isopropylphenyl) with trifluoromethanesulfonic acid (HOTf) or methyl trifluoromethylsulfonate (MeOTf) yields the corresponding protonated [(2-Im^Dipp)PH(4-Im^Dipp)]²⁺ (11²⁺) and methylated [(2-Im^Dipp)PMe(4-Im^Dipp)]²⁺ (12²⁺) dications, respectively. EPR/UV/Vis-NIR spectroelectrochemical investigation of the low-coordinated P^I cation 10⁺ predicted a stable and “bottleable” P-centered radical dication [(2-Im^Dipp)P(4-Im^Dipp)]^2+. (13^2+.). The reaction of 10⁺ with the nitrosyl salt NO[OTf] yields the persistent phosphanyl radical dication 13^2+. as triflate salt in crystalline form. Quantum chemical investigation revealed an exceptional high spin density at the P atom.

The reaction of the bis(imidazoliumyl)-substituted P^I cation [(2-Im^Dipp)P(4-Im^Dipp)]⁺ (10⁺) (2-Im=imidazolium-2-yl; 4-Im=imidazolium-4-yl; Dipp=2,6-di-isopropylphenyl) with trifluoromethanesulfonic acid (HOTf) or methyl trifluoromethylsulfonate (MeOTf) yields the corresponding protonated [(2-Im^Dipp)PH(4-Im^Dipp)]²⁺ (11²⁺) and methylated [(2-Im^Dipp)PMe(4-Im^Dipp)]²⁺ (12²⁺) dications, respectively. EPR/UV/Vis-NIR spectroelectrochemical investigation of the low-coordinated P^I cation 10⁺ predicted a stable and “bottleable” P-centered radical dication [(2-Im^Dipp)P(4-Im^Dipp)]^2+. (13^2+.). The reaction of 10⁺ with the nitrosyl salt NO[OTf] yields the persistent phosphanyl radical dication 13^2+. as triflate salt in crystalline form. Quantum chemical investigation revealed an exceptional high spin density at the P atom.

The trication (pyr₃P₂)³⁺ (1⁺, pyr = 3,5-dimethylpyrazolyl) is used as a convenient pyrazolyl-transfer reagent to convert 2-pyridones, 4-pyridones, and urea derivatives to pyrazolyl-substituted pyridinium or guanidinium triflate salts. This conversion represents a new, efficient, and highly functional-group-compatible approach that yields the desired products conveniently and in high yields. Typically, this reaction proceeds by exchange of the carbonyl oxygen atom of the substrate for a pyrazolyl moiety. However, for the structurally related 3-hydroxypyridines, a different reaction pathway occurs to give tripyridyl phosphites. The outcome of the reaction can be explained by the lactam–lactim tautomerism of the substrate and is discussed in detail. All reaction products were fully characterized by elemental analysis and multinuclear NMR, IR, and Raman spectroscopy, and the structural arrangements of most of the products were confirmed by X-ray crystallography analysis.

Compound Ph₃As(OTf)₂ as a pentacoordinated As^V Lewis acid readily forms dicationic Lewis acid/base adducts upon addition of various Lewis bases. It also represents a stronger chloride-abstracting agent than Me₃SiOTf and facilitates the reductive coupling of PCl₃ in the presence of AsPh₃ to the unprecedented cation [P₇(AsPh₃)₃]³⁺ as triflate salt. This crystallographically characterized nortricyclane-type cation represents a P₇R₃-derivative with the most electron-withdrawing substituents, resulting in a pronounced effect on the structural parameters of the P₇ core.

Cationic R₂P₅⁺ cage compounds (1⁺) have been synthesized by the stoichiometric reaction of R₂PCl, GaCl₃ and P₄. The reaction conditions depend on the substituent R. Alkyl-substituted derivatives (1 a–1 d[GaCl₄]) are best synthesized under solvent-free conditions, whereas aryl-substituted derivatives (1 e–1 h[GaCl₄]) are formed in C₆H₅F. All compounds have been prepared on a multi-gram scale in good to excellent yields and have been fully characterized with an emphasis on ³¹P NMR spectroscopy in solution and single-crystal structure determination. Subsequent chalcogenation reactions of cations R₂P₅⁺ (1 a⁺, 1 e⁺) and trication Ph₆P₇³⁺ (3³⁺) with elemental sulfur (α-S₈) or grey selenium (Se_grey) yielded a series of unique polyphosphorus–chalcogen cations (4 a⁺, 4 e⁺, 5 a⁺, 6²⁺ and 7²⁺), possessing nortricyclane-type molecular structures. An in-depth study of the ³¹P{¹H} and ⁷⁷Se NMR spectroscopic parameters is presented, and correlations between the substitution pattern and the observed structural features have been investigated in detail.