Crystal structure of an eight-co-ordinate manganese complex: bis-(3,4-di-2-pyridylpyridazine)dinitratomanganese(II)

Abstract

The crystal and molecular structures of the compound [Mn(dppn)₂(NO₃)₂](dppn = 3,6-di-2-pyridylpyridazine) have been determined by single-crystal X-ray diffraction photography, and refined anisotropically by the method of least squares to R 6·6% for 1816 independent observed reflections. The yellow crystals are triclinic, and the unit cell, of dimensions a= 8·88, b= 11·95, c= 14·20 (±0·03)Å, α= 107·0, β= 87·6, γ= 103·0 (±0·3)°, contains two enantiomorphous molecules. All four ligands are bidentate, giving an eight-co-ordinate complex roughly approximating to C₂ symmetry. The dppn molecules are nearly planar, and the two non-co-ordinating N atoms in each ligand are mutually trans. The four Mn–N bond lengths are all close to 2·30 Å. The co-ordination of one nitrate ion is symmetrical (Mn–O 2·46 Å), that of the other is unsymmetrical (Mn–O 2·30 and 2·47 Å). This compound and its cadmium analogue are isomorphous. The i.r. spectra in the region of nitrate vibrations are reported.