Potassium 2-(N-hydroxy-carbamo-yl)acetate monohydrate.

The crystal structure of the title compound, K(+)·C(3)H(4)NO(4) (-)·H(2)O, consists of potassium cations, monoanions of 2-carboxy-acetohydroxamic acid [namely 2-(N-hydroxy-carbamo-yl)acetate] and solvent water mol-ecules. The elements of the structure are united in a three-dimensional network by numerous K⋯O coordinate bonds and O-H⋯O and N-H⋯O hydrogen bonds. The coordination sphere of the K(+) ions may be described as a distorted double capped octa-hedron. Bond lengths and angles are similar to those in related compounds.

Crystal structure of µ-oxalodi-hydroxamato-bis-[(2,2'-bipyrid-yl)(di-methyl sulfoxide-κO)copper(II)] bis-(perchlorate).

The centrosymmetric binuclear complex, [Cu2(C2H2N2O4)(C10H8N2)2(C2H6OS)2](ClO4)2, contains two copper(II) ions, connected through an N-deprotonated oxalodi-hydroxamic acid dianion, two terminal 2,2'-bi-pyridine ligands, and two apically coordinating dimethylsulfoxide mol-ecules. Two non-coordinating perchlorate anions assure electrical neutrality. The copper(II) ions in the complex dication [Cu2(C10H8N2)2(µ-C2H2N2O4)(C2H6SO)2](2+) are in an O2N3 square-pyramidal donor environment, the Cu-Cu separation being 5.2949 (4) Å. Two hydroxamate groups in the deprotonated oxalodi-hydroxamic acid are located trans to one each other. In the crystal, O-H⋯O and C-H⋯O hydrogen bonds link the complex cations to the perchlorate anions. Further C-H⋯O hydrogen bonds combine with π-π contacts with a centroid-to-centroid separation of 3.6371 (12) Što stack the mol-ecules along the a-axis direction.