Synthesis, crystal structures and characterization of two heterometallic compounds: Ba3[Fe(C2O4)3]2(H2O)12 and Ba4.5[Fe4O(OH)3(C2O4)8](H2O)19

Heterometallic yellow compound Ba3[Fe(C2O4)3]2(H2O)12 (1) could be transformed to heterometallic red compound Ba4.5[Fe4O(OH)3(C2O4)8]-(H2O)19 (2) in solution. Ba2+ and Fe3+ formed three-dimensional network thorough oxalate anion and H2O molecules. 1 is a paramagnet and a strong antiferromagnetic interaction in OH/O bridged tetranuclear anion [Fe4O(OH)3(C2O4)89−] as ground state of S = 0 exists in 2.57