Single crystals of new Mn₂[Bi₂O](SeO₃)₄ (I), MnBi(SeO₃)₂Cl (II), Mn^IIMn^III(SeO₃)₂Cl (III), Mn₅(SeO₃)₂Cl₆ (IV), and Mn₄(Mn₅,Bi)(SeO₃)₈Cl₅ (V) have been synthesized by chemical vapour transport and hydrothermal methods. They have been structurally characterized by single crystal X-ray diffraction analysis. The compounds II-V are the first Mn selenite chlorides, while the I, II and V compounds are the first Bi-containing Mn oxoselenites. Structural relationships of the new phases with other compounds are discussed. An overview of the mixed-ligand MnO_mCl_n polyhedra in inorganic compounds is given.