@article{2928397, title = "Structural and spectral studies of N -alkyloxamates and their complexes: X-ray structures of MeHNCOCOOK and [Cu(EtHNCOCOO) 2 ], and vibrational studies", author = "G.S. Papaefstathiou and A. Peeters and A.T.H. Lenstra and H.O. Desseyn and S.P. Perlepes", journal = "Journal of Molecular Structure", year = "2001", volume = "559", number = "1-3", pages = "167--177", publisher = "ELSEVIER BV", issn = "0022-2860", doi = "10.1016/s0022-2860(00)00693-1", abstract = "This work is devoted to structural and vibrational studies of N-alkyloxamates and their complexes. The structures of MeHNCOCOOK and [Cu(EtHNCOCOO)(2)] have been determined by single-crystal X-ray crystallography. The potassium salt crystallizes in the monoclinic space group P2(1)/n and the copper(II) complex in the triclinic space group P (1) over bar. The lattice constants are a = 3.882(2), b = 10.175(1), c = 13.004(1), beta = 97.04(1)degrees for MeHNCOCOOK and a = 5.013(1), b = 6.996(1), c = 8.575(1) Angstrom, alpha = 73,54(1), beta = 85.66(1), gamma = 71.22(1)degrees for [Cu(EtHNCOCOO)(2)]. The salt has a trans secondary amide group and the K- ion is surrounded by seven O atoms belonging to six different N-methyloxamate(-1) moieties. The ligand EtHNCOCOO- behaves as a bidentate chelate in the trans square planar copper(II) complex with ligated atoms being the amide and one of the carboxylate oxygens. The copper(II) complex was characterized by its room-temperature magnetic susceptibility and solid-state d-d spectrum. A detailed comparison of the vibrational spectra (FT-IR, FT-Raman) of [Cu(EtHNCOCOO)(2)] with the corresponding potassium salt, EtHNCOCOOK, is presented. The vibrational data are discussed in terms of the nature of bonding and the known structure of the copper(II) complex. Quantum-chemical calculations were performed to obtain the equilibrium geometries and torsional energies for an isolated oxamate(-1) ion (H2NCOCOO-) and its hypothetical square planar zinc(II) complex. (C) 2001 Elsevier Science B.V, All rights reserved." }