Cupferron

Chemical compound

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

Structure of ferric cupferron complex

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. 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 IIron 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.