Crystal structure and properties of K{sub 2}[OsO{sub 2}(C{sub 2}O{sub 4}){sub 2}] . 2H{sub 2}O

The synthesis and X-ray diffraction study of the compound K{sub 2}[OsO{sub 2}(C{sub 2}O{sub 4}){sub 2}] . 2H{sub 2}O are performed. The compound crystallizes in the triclinic crystal system, space group P1-bar, a = 6.545(1) A, b = 6.835(2) A, c = 7.595(2) A, {alpha} = 85.76(2) deg., {beta} = 65.33(2) deg., {gamma} = 71.14(2) deg., and Z = 1. The osmium atom is located at the center of symmetry and has a distorted octahedral coordination formed by oxygen atoms: two oxygen atoms of the osmyl group occupy the apical positions [Os-O, 1.730(2) A], and four oxygen atoms of the oxalate ions lie in the equatorial plane. The K{sup +} cation is surrounded by ten oxygen atoms located at different K-O distances in the range from 2.787(2) to 3.158(2) A. The assignment of the absorption bands in the IR spectrum of K{sub 2}[OsO{sub 2}(C{sub 2}O{sub 4}){sub 2}] . 2H{sub 2}O is performed. The electronic absorption spectra of the compound are recorded in different solvents, and the thermal behavior in air is studied.