Aqueous Chemistry of Chlorocyclophosphazenes: Phosphates {PO2}, Phosphamides {P(O)NHR}, and the first Phosphites {PHO} and Pyrophosphates {(PO)2O} of These Heterocycles

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• 作者：Joanne Ledger ; Ramamoorthy Boomishankar ; Alexander Steiner
• 刊名：Inorganic Chemistry
• 出版年：2010
• 出版时间：April 19, 2010
• 年：2010
• 卷：49
• 期：8
• 页码：3896-3904
• 全文大小：1042K
• 年卷期：v.49,no.8(April 19, 2010)
• ISSN：1520-510X

文摘

Cyclotriphosphazenes have been functionalized with various oxo-groups at one of the ring phosphorus atoms. Starting from geminal dichlorides (A) which are equipped with amino groups at the other two phosphorus atoms {(Z′₂P)₂N₃PCl₂ (Z′ = NHCy) and (Z′′P)₂N₃PCl₂ (Z′′ = {EtN(C₃H₆)NEt}), respectively}, phosphate (B), pyrophosphate (C), phosphamide (D), and phosphite (E) derivatives have been prepared. The zwitterionic phosphate (Z′₂P)₂N₃H₂PO₂ B is obtained via the 4-dimethylamino pyridine (dmap)-catalyzed hydrolysis of A in a biphasic mixture of aqueous KOH and tetrahydrofuran (thf). B contains a PO₂ moiety neighboring two protonated ring nitrogen sites. It crystallizes as the tetrahydrate (Z′₂P)₂N₃H₂PO₂·4H₂O, which consists of a double helix: A helical chain of hydrogen bonded zwitterions is intertwined with a helical chain of water molecules. The reaction of A with only dmap in CHCl₃ produces the dication [(Z′₂P)₂N₃P(dmap)₂]²⁺, which binds two dmap ligands at one phosphorus atom. The tetrahydrate dehydrates at 160 °C in vacuo under formation of the pyrophosphate {(Z′₂P)₂N₃HPO}₂O C, which contains a O═P−O−P═O residue linking the two phosphazene rings. When heated in a mixture of aqueous KOH, primary amine, and thf, A undergoes a concurrent aminolysis-hydrolysis reaction, which gives the phosphamide (Z₂P)₂N₃HP(O)NHR D featuring a P(=O)NHR residue. The corresponding reaction of A with α,α′-diamino-p-xylene in a 2:1 ratio leads to the formation of {(Z′₂P)₂N₃HP(O)NHCH₂}₂C₆H₄, in which two phosphamide moieties are linked by a xylylene bridge. Phosphites E containing PHO moieties are obtained via reduction of the dichloride with potassium and subsequent treatment with KOH. The product consists of a hexameric potassium complex, which features a central K₆O₆ double cube arrangement and contains the anionic ligand [(Z′′P)₂N₃PHO]⁻ that offers two bidentate N−P−O coordination sites. Addition of NH₄Cl yields the neutral phosphite (Z′′P)₂N₃HPHO. The title compounds are amphiphilic featuring hydrophilic NH and PO_x moieties and hydrophobic alkyl groups. In addition, they show amphiprotic behavior via protonation/deprotonation at ring N atoms.