Cyclodiphosphazane
{{Short description|Class of chemical compounds}}
Cyclodiphosphazanes are saturated four membered P2N2 ring systems and one of the major classes of cyclic phosphazene compounds.{{Cite journal |last1=Yang |first1=Yun-Fang |last2=Cheng |first2=Gui-Juan |last3=Zhu |first3=Jun |last4=Zhang |first4=Xinhao |last5=Inoue |first5=Shigeyoshi |last6=Wu |first6=Yun-Dong |date=2012-06-11 |title=Silicon-containing formal 4π-electron four-membered ring systems: antiaromatic, aromatic, or nonaromatic? |url=https://pubmed.ncbi.nlm.nih.gov/22532432/ |journal=Chemistry: A European Journal |volume=18 |issue=24 |pages=7516–7524 |doi=10.1002/chem.201103443 |issn=1521-3765 |pmid=22532432}} Bis(chloro)cyclodiphosphazanes, (cis-[ClP(μ-NR)]2) are important starting compounds for synthesizing a variety of cyclodiphosphazane derivatives by nucleophilic substitution reactions; are prepared by reaction of phosphorus trichloride (PCl3) with a primary amine (RNH2) or amine hydrochlorides (RNH3Cl).{{Cite journal |last1=Chandrasekaran |first1=P. |last2=Mague |first2=Joel T. |last3=Balakrishna |first3=Maravanji S. |date=March 30, 2011 |title=Synthesis and Derivatization of the Bis(amido)-λ 3 -cyclodiphosphazanes cis -[R′(H)NP(μ-NR)] 2 , Including a Rare Example, trans -[ t Bu(H)N(Se)P(μ-NCy)] 2 , Showing Intermolecular Se···H–O Hydrogen Bonding |url=https://onlinelibrary.wiley.com/doi/10.1002/ejic.201001348 |journal=European Journal of Inorganic Chemistry |language=en |volume=2011 |issue=14 |pages=2264–2272 |doi=10.1002/ejic.201001348 |issn=1434-1948}}
Organic substituents on nitrogen play an important role in formation of cyclic phosphazane compounds.{{Cite journal |last1=Jezuita |first1=Anna |last2=Ejsmont |first2=Krzysztof |last3=Szatylowicz |first3=Halina |date=2021-02-01 |title=Substituent effects of nitro group in cyclic compounds |journal=Structural Chemistry |language=en |volume=32 |issue=1 |pages=179–203 |doi=10.1007/s11224-020-01612-x |issn=1572-9001|doi-access=free }} The cyclic tetramers and trimer are formed with methyl and ethyl substituents on nitrogen, whereas formation of cyclic dimers (cis-[ClP(μ-NR)]2) have been observed exclusively with more sterically demanding primary amines such as tert-butylamine and aniline.{{Cite journal|last1=Balakrishna|first1=Maravanji S.|last2=Eisler|first2=Dana J.|last3=Chivers|first3=Tristram|date=2007|title=Chemistry of pnictogen(III)–nitrogen ring systems |journal=Chem. Soc. Rev.|volume=36|issue=4|pages=650–664|doi=10.1039/b514861h |pmid=17387412}}
Coordination Chemistry
Cyclodiphosphazanes are excellent ligand systems for metallosupramolecular chemistry.{{Cite journal |last=Balakrishna |first=Maravanji S. |date=2016-08-02 |title=Cyclodiphosphazanes: options are endless |url=https://pubmed.ncbi.nlm.nih.gov/27430043/ |journal=Dalton Transactions |volume=45 |issue=31 |pages=12252–12282 |doi=10.1039/c6dt01121g |issn=1477-9234 |pmid=27430043}} 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 and gold centers and metallopolymers CuX, AgX.{{Cite journal|last1=Ananthnag|first1=Guddekoppa S.|last2=Kuntavalli|first2=Seema|last3=Mague|first3=Joel T.|last4=Balakrishna|first4=Maravanji S.|date=2012-05-07|title=Resorcinol Based Acyclic Dimeric and Cyclic Di- and Tetrameric Cyclodiphosphazanes: Synthesis, Structural Studies, and Transition Metal Complexes |journal=Inorganic Chemistry|volume=51|issue=10|pages=5919–5930|doi=10.1021/ic300541n |pmid=22564192}}
Chiral cyclodiphosphazanes have found use as ligands in asymmetric catalysis. Gade et al. employed them in enantioselective transition-metal mediated catalysis,{{Cite journal|last1=Roth|first1=Torsten|last2=Wadepohl|first2=Hubert|last3=Wright|first3=Dominic S.|last4=Gade|first4=Lutz H.|date=2013-08-28|title=Chiral Ditopic Cyclophosphazane (CycloP) Ligands: Synthesis, Coordination Chemistry, and Application in Asymmetric Catalysis |journal=Chemistry - A European Journal|volume=19|issue=41|pages=13823–13837|doi=10.1002/chem.201302327 |pmid=24038171}} while Goldfuss et al. employed di-amino substituted chiral variants in hydrogen bonding catalysis.{{Cite journal|last1=Klare|first1=Helge|last2=Neudörfl|first2=Jörg M.|last3=Goldfuss|first3=Bernd|date=2014-01-21|title=New hydrogen-bonding organocatalysts: Chiral cyclophosphazanes and phosphorus amides as catalysts for asymmetric Michael additions |journal=Beilstein Journal of Organic Chemistry|volume=10|issue=1|pages=224–236|doi=10.3762/bjoc.10.18 |pmc=3944119|pmid=24605142}}
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.{{Cite journal|last1=Klare|first1=Helge|last2=Hanft|first2=Sebastian|last3=Neudörfl|first3=Jörg M.|last4=Schlörer|first4=Nils E.|last5=Griesbeck|first5=Axel|last6=Goldfuss|first6=Bernd|date=2014-09-08|title=Anion Recognition with Hydrogen-Bonding Cyclodiphosphazanes|url=https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.201403013|journal=Chemistry – A European Journal|volume=20|issue=37|pages=11847–11855|doi=10.1002/chem.201403013|pmid=25079663|issn=0947-6539}}{{Cite journal|last1=Wolf|first1=Florian F.|last2=Neudörfl|first2=Jörg-M.|last3=Goldfuss|first3=Bernd|date=2018-03-26|title=Hydrogen-bonding cyclodiphosphazanes: superior effects of 3,5-(CF3)2-substitution in anion-recognition and counter-ion catalysis|url=https://pubs.rsc.org/en/content/articlelanding/2018/nj/c7nj04660j|journal=New Journal of Chemistry|language=en|volume=42|issue=7|pages=4854–4870|doi=10.1039/C7NJ04660J|issn=1369-9261}}{{Cite journal|last1=Plajer|first1=Alex J.|last2=Zhu|first2=Jinbo|last3=Proehm|first3=Patrick|last4=Bond|first4=Andrew D.|last5=Keyser|first5=Ulrich F.|last6=Wright|first6=Dominic S.|date=2019-06-05|title=Tailoring the Binding Properties of Phosphazane Anion Receptors and Transporters|url=https://doi.org/10.1021/jacs.9b00504|journal=Journal of the American Chemical Society|volume=141|issue=22|pages=8807–8815|doi=10.1021/jacs.9b00504|pmid=31079456|bibcode=2019JAChS.141.8807P |s2cid=153304971|issn=0002-7863}}{{Cite journal|last1=Plajer|first1=Alex J.|last2=Zhu|first2=Jinbo|last3=Pröhm|first3=Patrick|last4=Rizzuto|first4=Felix J.|last5=Keyser|first5=Ulrich F.|last6=Wright|first6=Dominic S.|date=2020-01-15|title=Conformational Control in Main Group Phosphazane Anion Receptors and Transporters|url=https://doi.org/10.1021/jacs.9b11347|journal=Journal of the American Chemical Society|volume=142|issue=2|pages=1029–1037|doi=10.1021/jacs.9b11347|pmid=31877039|bibcode=2020JAChS.142.1029P |s2cid=209490378|issn=0002-7863}}{{Cite journal|last1=Shi|first1=Xiaoyan|last2=León|first2=Felix|last3=Sim|first3=Ying|last4=Quek|first4=Shina|last5=Hum|first5=Gavin|last6=Khoo|first6=Yi Xin Joycelyn|last7=Ng|first7=Zi Xuan|last8=Par|first8=Mian Yang|last9=Ong|first9=How Chee|last10=Singh|first10=Varun K.|last11=Ganguly|first11=Rakesh|title=N-Bridged Acyclic Trimeric Poly-Cyclodiphosphazanes: Highly Tuneable Cyclodiphosphazane Building Blocks|journal=Angewandte Chemie International Edition|year=2020|volume=59|issue=49|pages=22100–22108|language=en|doi=10.1002/anie.202008214|pmid=32696527|issn=1521-3773|doi-access=free}}
References
External links
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