Cyclodiphosphazanes are saturated four membered P₂N₂ ring systems and one of the major classes of cyclic

phosphazene Phosphazenes refer to classes of organophosphorus compounds featuring phosphorus(V) with a double bond between P and N. One class of phosphazenes have the formula . These phosphazenes are also known as iminophosphoranes and phosphine imides. They a ...

compounds. Bis(chloro)cyclodiphosphazanes, (cis- lP(μ-NR)sub>2) are important starting compounds for synthesizing a variety of cyclodiphosphazane derivatives by

nucleophilic substitution In chemistry, a nucleophilic substitution is a class of chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass c ...

reactions; are prepared by reaction of

phosphorus trichloride Phosphorus trichloride is an inorganic compound with the chemical formula PCl3. A colorless liquid when pure, it is an important industrial chemical, being used for the manufacture of phosphites and other organophosphorus compounds. It is toxic a ...

(PCl₃) with a

primary amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent such ...

(RNH₂) or amine hydrochlorides (RNH₃Cl). Organic

substituent A substituent is one or a group of atoms that replaces (one or more) atoms, thereby becoming a moiety in the resultant (new) molecule. (In organic chemistry and biochemistry, the terms ''substituent'' and '' functional group'', as well as '' ...

s on nitrogen play an important role in formation of cyclic phosphazane compounds. The cyclic tetramers and trimer are formed with methyl and ethyl substituents on nitrogen, whereas formation of cyclic dimers (cis- lP(μ-NR)sub>2) have been observed exclusively with more sterically demanding primary amines such as ''tert''-butylamine and

aniline Aniline is an organic compound with the formula C6 H5 NH2. Consisting of a phenyl group attached to an amino group, aniline is the simplest aromatic amine. It is an industrially significant commodity chemical, as well as a versatile start ...

Coordination Chemistry

Cyclodiphosphazanes are excellent ligand systems for metallosupramolecular chemistry. The cis-oriented lone pair on phosphorus in cyclodiphosphazane are projected away from each other, so chelation to metal center is not possible. This bridging coordination of cyclodiphosphazane allows formation of metallomacrocycles containing four

rhodium Rhodium is a chemical element with the symbol Rh and atomic number 45. It is a very rare, silvery-white, hard, corrosion-resistant transition metal. It is a noble metal and a member of the platinum group. It has only one naturally occurring ...

and

gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile ...

centers and metallopolymers CuX, AgX. Chiral cyclodiphosphazanes have found use as ligands in asymmetric catalysis. Gade et al. employed them in enantioselective transition-metal mediated catalysis, while Goldfuss et al. employed di-amino substituted chiral variants in hydrogen bonding catalysis. Cyclodiphosphazanes have also been found to have a high ability to bind anions via hydrogen bonding - specifically halides - in both their monomeric and macrocyclic forms. They are competitive to or better than comparable bifurcated anion binding structural motifs such as (thio)urea and squaramide.

References

External links

*{{Commons category-inline Nitrogen compounds Phosphorus compounds Four-membered rings