Networks. -The title compounds are prepared from the elements (Ta tubes, 1100 K, 48 h) and characterized by powder XRD and magnetic susceptibility measurements. Single crystal XRD data are reported for BaCo2Sn8. Both compounds crystallize with a new structure type in the space group Cccm (Z = 8). The structure of the Ba compound contains CoSn 7 units, which are condensed via common rectangular faces to [Co2Sn10] dimers. The double units form a covalently bonded three-dimensional network through Sn-Co-Sn bridges. BaCo2Sn8 exhibits Pauli paramagnetism. -(SCHWICKERT, C.; POETTGEN*, R.; Z. Naturforsch., B: Chem. Sci. 68b (2013) 1, 17-22, http://dx.