SYNTHESIS AND MOLECULAR-STRUCTURE OF 2 CRYSTALLINE FORMS OF HYDRATED CERIUM(III) PICRATE

The compound of formula Ce(pic)3.12H2O (pic = picrate, C6H2N3O7) has been synthesized and crystallized in two different forms. The X-ray structure of both forms has been determined; form 1 is monoclinic, space group P2(1)/n, a = 7.799(2), b = 26.925(2), c = 17.465(2) angstrom, beta = 98.93(3)degrees, V = 3623(2) angstrom3, Z = 4, D(x) = 1.908 g cm-3; form 2 is monoclinic, space group C2/c, a = 40.225(5), b = 8.008(4), c = 24.351(9), beta = 111.46(2)degrees, V = 7300(8) angstrom3, Z = 8, D(x) = 1.893 g cm-3. The molecular structure of the two forms is essentially the same, with the Ce3+ ion coordinated to six water molecules, one phenolic oxygen from one picrate ion and two oxygens, one from a phenolic and the other from a nitro group of a second picrate giving a coordination number nine; a third picrate ion and six additional water molecules (in different positions in the two forms) complete the crystal packing through a complex network of hydrogen bonds.