Synthesis and structure of three manganese oxalates: MnC₂O₄·2H₂O, [C₄H₈(NH₂)₂][Mn₂(C₂O₄)₃] and Mn₂(C₂O₄)(OH)₂

Three manganese oxalates have been hydrothermally synthesized, and their structures determined by single-crystal X-ray diffraction. MnC2O4.2H(2)O (1) is orthorhombic, P2(1)2(1)2(1), a = 6.262(4) Angstrom, b = 13.585(5) Angstrom c = 6.091(4) Angstrom, V = 518.2(4) Angstrom(3), Z = 4, final R, R-w = 0.0832, 0.1017 for 561 observed data (I>3sigma(I)). The one-dimensional structure consists of chains of oxalate-bridged manganese centers. [C4H8(NH2)(2)][Mn-2(C2O4)(3)] (II) is triclinic, P (1) over bar a = 5.9305(5) Angstrom, b = 7.7763(7) Angstrom, c = 8.1707(7) Angstrom, alpha = 81.489(2)degrees, beta = 81.045(2)degrees, gamma = 86.076(2)degrees, V = 367.72(5) Angstrom(3), Z = 1, final R, R-w = 0.0467. 0.0596 for 1773 observed data (I > 3sigma (I)). The Z = 1, final R, R, three-dimensional framework is constructed from seven coordinate manganese and oxalate anions. The material contains extra-framework diprotonated piperazine cations. Mn-2(C2O4)(OH)(2) (III) is monoclinic, P2(1)/c, a = 5.926(1) Angstrom, b = 5.695(1) Angstrom, c = 7.494(2) Angstrom, beta = 91.10(3)degrees, V = 252.88(9)Angstrom, Z = 1. final R-1, wR2 = 0.0710, 0.1378 for 268 observed data (I > 2sigma (I)). The structure is also three dimensional, with layers of MnO6 octahedra pillared by oxalate anions. The hydroxide group is found bonded to three manganese centers resulting in a four coordinate oxygen. (C) 2003 Elsevier Science (USA). All rights reserved.