title: 15N-1H and 15N-13C couplings in 15N-enriched dihydroxamic acids.
abstract: (15)N-enriched dihydroxamic acids (HONHCO(CH(2))(n)CONHOH, n = 0, 1, and 2) were prepared and their spectra NMR ((1)H, (13)C, (15)N) recorded in dimethyl sulfoxide (DMSO) solutions with the aim of determining (15)N coupling constants ((15)N-(1)H and (15)N-(13)C). The results supplement chemical shifts published earlier and yield additional support to the structural conclusions derived from other NMR parameters. Notably, no trace of hydroximic structures could be found in the (15)N NMR spectra of these acids. The values of (15)N-(13)C coupling constants backed by theoretical calculations support the assignments made earlier for all of the major conformers and for the minor conformer of succinohydroxamic acid. The enrichment revealed that the minor component of malonodihydroxamic acid solution previously considered to be the ZE conformer is in fact the monohydroxamic acid (HOOC-CH(2)-CO-NH-OH).
authors.affiliation: Institute of Chemical Process Fundamentals of the ASCR, v. v. i., Rozvojová 135, 16502 Prague 6, Czech Republic. schraml@icpf.cas.cz
authors.forename: Jan
authors.initials: J
authors.lastname: Schraml
authors.forename: Petr
authors.initials: P
authors.lastname: Cigler
mesh_terms: D002247:Carbon Isotopes; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D008968:Molecular Conformation; D009587:Nitrogen Isotopes; D010072:Oxamic Acid / Q000031:analogs & derivatives / Q000138:chemical synthesis / Q000737:chemistry; D011522:Protons
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D011522:Protons; D010072:Oxamic Acid