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Speciation 98: Abstracts
G. Bell1, D.A. Brown1, L. Cuffe1, W. Errington2, E. Farkas3, N.J. Fitzpatrick1, W. K. Glass1, T. J. Kemp2
1 Dept. of Chemistry, University College Dublin, Ireland;
2 Dept. of Chemistry, University of Warwick, U.K.;
3 Dept. of Inorganic analytical Chemistry, Lajos Kossuth University, Debrecen, Hungary
Glycinehydroxamic acid, NH2CH2CONHOH, exhibits an interesting coordination behaviour with transition metals (1), providing the first example of N,N coordination in Ni(GHA)2 (2). The free acid exists in the crystalline state as a zwritterion formed by proton transfer of the amino proton to the terminal NH2 group (+NH3CH2CON-OH) together with a network of hydrogen bonds (3). However, reaction of GHA with sodium molybdate dihydrate, although exhibiting quite complicated solution equilibria (4), yields the O,O bonded complex, MoO2(GHA)2, with structure (Fig 1) close to the reported for simple monohydroxamic acids such as hexanohydroxamic acid (5). The factors responsible for this varied conformational and complexation behaviour are not clear so calculations of the electronic structure of GHA in various conformations and in various solvents have been carried out at both the HF optimizations with MP2 single point energies and density functional method. Results from both the Onsager and the Isodensity model of Keith, Frisch, Foresmann et al. (6), as implemented in G94, are reported in an attempt to clarify the various factors involved. In addition, the results of normal coordinate analyses of these systems are presented.
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