Dimeric cerium (IV) peroxide complexes:

The [Ce(O2)2Ce]4+ unit, with bridging, doubly bidentate, peroxy-groups, found previously in salts of Ce2(O2)2(CO3)68+ has been found in an edta complex, K2Na2[(edta)Ce(O2)2Ce(edta)].13H2O. Triclinic, Panti 1, a = 8.412(1), b = 9.789(2), c = 10.186(2) A, α = 96.20(2), β = 102.87(1), γ = 112.20(2)deg, R = 0.025 for 2475 reflexions. The edta anions cap the outer sides of the Ce(IV) atoms, with Ce-O 2.418 A and Ce-N 2.716 A, to give a total of 10-coordination for the Ce atoms. The carbonato-anion has been crystallised as the (6K+, 2Na+, 8H2O) salt. Monoclinic, I2/a, a = 14.3691(15), b = 12.5011(26), c = 24.2535(40) A, β = 101.45(1)deg, R = 0.034 for 3287 reflexions. In this structure the anion is somewhat more distorted than in the 8K+ and 8Na+ salts. (orig.)