Cupferron Explained

Cupferron is jargon for the ammonium salt of the conjugate base derived from N-nitroso-N-phenylhydroxylamine. It once was a common reagent for the complexation of metal ions, being of interest in the area of qualitative inorganic analysis. Its formula is NH₄[C₆H₅N(O)NO]. The anion binds to metal cations through the two oxygen atoms, forming five-membered chelate rings.

Synthesis and complexes

Cupferron is prepared from phenylhydroxylamine and an NO⁺ source:^[1]

C₆H₅NHOH + C₄H₉ONO + NH₃ → NH₄[C₆H₅N(O)NO] + C₄H₉OH

Being a bidentate mono-anionic ligand, CU⁻ forms complexes analogous to those produced with acetylacetonate. Illustrative complexes include Cu(CU)₂, Fe(CU)₃, and Zr(CU)₄.^{[2] [3] [4]}

References

1. 10.15227/orgsyn.004.0019. Cupferron. Organic Syntheses. 1925. 4. 19. C. S. Marvel.
2. 10.1107/S0108270195002770. Bis(cupferronato)copper(II), [Cu(C₆H₅N₂O₂)₂]. 1995. Elerman. Y.. Atakol. O.. Svoboda. I.. Geselle. M.. Acta Crystallographica Section C Crystal Structure Communications. 51. 8. 1520–1522.
3. 10.1107/S0365110X65000816. The Crystal Structure of IIron Cupferron Fe(O₂N₂C₆H₅)₃. 1965. Van Der Helm. D.. Merritt. L. L.. Degeilh. R.. MacGillavry. C. H.. Acta Crystallographica. 18. 3. 355–362. free.
4. 10.3891/acta.chem.scand.24-1398. The Crystal Structure of Zirconium Cupferrate, Zr(C₆H₅N₂O₂)₄. 1970. Mark. Wanda. Aava. Ulf. Haaland. A.. Resser. Dag. Rasmussen. S. E.. Sunde. Erling. Sørensen. Nils Andreas. Acta Chemica Scandinavica. 24. 1398–1414. free.