Structure and ESR spectra of single crystals of potassium bis(malonato)cuprate

The present paper gives the results ofmeasurementsof the ESR spectra and the preliminary results of an x-ray structural analysis of the potassium bis(malonato)cuprates KzCu(CsHzO~)- nH20 (n= 2 or 3). The compounds were obtained by cooling a 0.2 M solution containing potassium malonate and copper sulfate in the ratio 2: 1. The crystals separated in the form of rhomb-shaped platelets with well developed (010) faces. In some specimens the faces of the orthorhombic biwramid (111) predominated, and the lower part, adjacent to the foot of the crystallization vessel, was suppressed. For the x-ray diffraction studies we isolated crystals with two different compositions: K2Cu(C~H204) 2. 3H20 (I) and K2Cu(C3H204)z" 2HzO (II). The main bulk of the larger crystals with the composition I did not differ in color and faceting from the crystals with the composition II. In a large number of repeated experiments, we were able to obtain only one of the modifications (with the composition I) in pure form. The crystals with the composition II are unstable in air, so that for these crystals we obtained a limited set of intensities of the x-ray reflections, and their chemical composition was determined precisely during the struerare determination. The unit eel1 parameters were determined from x-ray rotation patterns and scannings of the equatorial layer