Crystal structure analysis of silver oxalate, Ag2C2O4 and X-ray diffraction study of its single crystal at the initial stage of photolysis

Abstract

The crystal structure of Ag2C2O4 was determined; space group P21/c, a=3.4603(5), b=6.1972(9), c=9.548(2) A, β=103.47(1)0, V=199.12(6) A3, Z=2, dcalc=5.066 g/cm3 (Syntex P21 automatic diffractometer, CuKα radiation, ф/2ф scan mode with a rate of 1.98–14.5 deg/min to 2θmax=115°, 548 measured and 274 independent Ihkl, R(F)=0.259). The structure is channel type ionic, with single-layer packing of anions in the (100) plane according to the hexagonal law. In the channels stretched along [100], there are silver dimers with the Ag−Ag distance of 2.945 A. The C2O 4 2− anion has $$\bar 1$$ symmetry; the C−C bond lengths are 1.60(1) and C−O are 1.23(1) and 1.24(1) A. The observation and X-ray diffration monitoring of the initial stage of photolysis allowed us to conclude that it proceeds in a thin surface layer and has no effect on the crystal struture. The obtained results are discussed in the light of the literature data on the photolysis and thermolysis mechanisms of Ag2C2O4. The results of previous structural studies are analyzed.