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Other names
ammonium N-nitrosophenylhydroxylamine
3D model (JSmol)
EC Number
  • 205-183-2
Molar mass 155.15 g/mol
Melting point 150 to 155 °C (302 to 311 °F; 423 to 428 K)
GHS pictograms GHS06: ToxicGHS07: HarmfulGHS08: Health hazard
GHS Signal word Danger
H301, H315, H319, H335, H351
P201, P202, P261, P264, P270, P271, P280, P281, P301+310, P302+352, P304+340, P305+351+338, P308+313, P312, P321, P330, P332+313, P337+313, P362, P403+233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

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]


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