Mangan(II)-Komplexe mit dem vierzähnigen Stickstoffliganden C 12 H 22 N 6 (L): Synthese von [MnX 2 L] (X = Cl, Br, I, NCS), Kristallstrukturen von [MnCl 2 L] und [MnBr 2 L] / Manganese(II) Complexes with the Tetradentate Nitrogen Ligand C 12 H 22 N 6 (L): Synthesis of [MnX 2 L] (Χ = Cl, Br, I, NCS), Crystal Structures of [MnCl 2 L] and [MnBr 2 L]