Synthesis and structure of three manganese oxalates: MnC 2O 4·2H 2O, [C 4H 8(NH 2) 2][Mn 2(C 2O 4) 3] and Mn 2(C 2O 4)(OH) 2

Abstract

Three manganese oxalates have been hydrothermally synthesized, and their structures determined by single-crystal X-ray diffraction. MnC 2O 4·2H 2O ( I) is orthorhombic, P2 12 12 1, a =6.262(4) A ̊ , b =13.585(5) A ̊ , c =6.091(4) A ̊ , V =518.2(4) A ̊ 3 , Z=4, final R, R w=0.0832, 0.1017 for 561 observed data ( I>3 σ( I)). The one-dimensional structure consists of chains of oxalate-bridged manganese centers. [C 4H 8(NH 2) 2][Mn 2(C 2O 4) 3] ( II) is triclinic, P 1 ̄ , a =5.9305(5) A ̊ , b =7.7763(7) A ̊ , c =8.1707(7) A ̊ , α=81.489(2)°, β=81.045(2)°, γ=86.076(2)°, V =367.72(5) A ̊ 3 , Z=1, final R, R w=0.0467, 0.0596 for 1773 observed data ( I > 3 σ ( I)). The three-dimensional framework is constructed from seven coordinate manganese and oxalate anions. The material contains extra-framework diprotonated piperazine cations. Mn 2(C 2O 4)(OH) 2 ( III) is monoclinic, P2 1/ c, a =5.926(1) A ̊ , b =5.695(1) A ̊ , c =7.494(2) A ̊ , β=91.10(3)°, V =252.88(9) A ̊ 3 , Z=1, final R 1, w R2=0.0710, 0.1378 for 268 observed data ( I>2 σ ( I)). The structure is also three dimensional, with layers of MnO 6 octahedra pillared by oxalate anions. The hydroxide group is found bonded to three manganese centers resulting in a four coordinate oxygen.