Group 13 Superacid Adducts of [PCl₂N]₃

Abstract

Irrespective of the order of the addition of reagents, the reactions of [PCl2N]3 with MX3 (MX3 = AlCl3, AlBr3, GaCl3) in the presence of water or gaseous HX give the air- and light-sensitive superacid adducts [PCl2N]3·HMX4. The reactions are quantitative when HX is used. These reactions illustrate a Lewis acid/Brønsted acid dichotomy in which Lewis acid chemistry can become Brønsted acid chemistry in the presence of adventitious water or HX. The crystal structures of all three [PCl2N]3·HMX4 adducts show that protonation weakens the two P-N bonds that flank the protonated nitrogen atom. Variable-temperature NMR studies indicate that exchange in solution occurs in [PCl2N]3·HMX4, even at lower temperatures than those for [PCl2N]3·MX3. The fragility of [PCl2N]3·HMX4 at or near room temperature and in the presence of light suggests that such adducts are not involved directly as intermediates in the high-temperature ring-opening polymerization (ROP) of [PCl2N]3 to give [PCl2N]n. Attempts to catalyze or initiate the ROP of [PCl2N]3 with the addition of [PCl2N]3·HMX4 at room temperature or at 70 °C were not successful.

RETRACTED ARTICLE: Synthesis and characterization of trimeric phosphazene based ionic liquids with tetrafluoroborate anions and their thermal investigations

“…[PCl 2 N] 3 ·MX 3 obtained by excluding water or HX is the main product. Whenever MX 3 (AlCl 3 , GaCl 3 , AlBr 3 ) was used, water traces were always found, and by isolating [PCl 2 N] 3 ·HMX 4 (HMX 4 : HAlCl 4 , HGaCl 4 , HAlBr 4 ) structures as the second product, they detected the location of the protonation by X-ray crystallography 11 , 12 . In recent years, PILs have been synthesized using a variety of cyclophosphazene compounds and bulky acids (salicylic, gentisic, γ-resorcylic acids), and the biological activity of these PMOSs has been investigated 13 – 15 .…”

Phosphazene-Based Ionic Liquids

“…The protonated specie distorted the P 3 N 3 ring and weakened the two P − N bonds that flank the protonated nitrogen. The crystal structures of Figure 4 [21,22].…”

New Synthetic Approach to Molecular Rods Using Cyclophosphazene-Based Oligospiranes

“…Therefore, the search for new types of rod structures and the development of new efficient synthetic methods have been intensively studied research areas in the last decades . Cyclic phosphazenes are a remarkable group of inorganic heterocycles that can serve as templates for the construction of new derivatives having properties that lead to a large variety of applications. − New derivatives can be easily obtained by the substitution reactions of the halogens (usually chlorine) attached to phosphorus atoms with various nucleophiles. ,− It is known that the reaction of cyclic phosphazenes with a tetrafunctional alcohol such as pentaerythritol gives spirane-bridged compounds whose structures consist of four six-membered rings, each joined at a tetrahedral phosphorus or carbon atom to the next ring . Recently, deprotonation reactions were used to form fused cyclophosphazene rings joined by a phosphazene or phosphazane ring.…”