Crystal-To-Crystal Transformation From K-2[Co(C2o4)(2)(H2o)(2)]Center Dot 4h(2)O To K-2[Co(Mu-C2o4)(C2o4)]

Crystal-to-crystal transformation is a path to obtain crystals with different crystal structures and physical properties. K-2[Co(C2O4)(2)(H2O)(2)]center dot 4H(2)O (1) is obtained from K2C2O4 center dot 2H(2)O, CoCl2 center dot 6H(2)O in H2O with a yield of 60%. It is crystallized in the triclinic with space group P1 and cell parameters: a = 7.684(1) angstrom, b = 9.011(1) angstrom, c = 10.874(1) angstrom, alpha = 72.151(2)degrees, beta = 70.278(2)degrees, gamma = 80.430(2)degrees, V = 670.0(1) angstrom(3), Z = 2 at 100 K. 1 is composed of K+, mononuclear anion [Co(C2O4)(2)(H2O)(2)(2-)] and H2O. Co2+ is coordinated by two bidentated oxalate anion and two H2O in an octahedron environment. There is a hydrogen bond between mononuclear anion [Co(C2O4)(2)(H2O)(2)(2-)] and H2O. K-2[Co(mu-C2O4)(C2O4)] (2) is obtained from 1 by dehydration. The cell parameters of 2 are a = 8.460(5) angstrom, b = 6.906 (4) angstrom, c = 14.657(8) angstrom, beta = 93.11(1)degrees, V = 855.0(8) angstrom(3) at 100 K, with space group in P2/c. It is composed of K+ and zigzag [Co(mu-C2O4)(C2O42-](n) chain. Co2+ is coordinated by two bisbendentate oxalate and one bidentated oxalate anion in trigonal-prism. 1 is an antiferromagnetic molecular crystal. The antiferromagnetic ordering at 8.2 K is observed in 2.