A New Chain-Like Heteropolytungstate Formed by Keggin Cluster Units: Synthesis and Structure of [H 2 bpy] 3 [SiMnW 11 O 39 ]·1.25H 2 O. -The title compound is hydrothermally synthesized from an aqueous solution containing K8[β2-SiW11O39]·14H2O, MnCl2, and 4,4'-bipyridine (autoclave, 130°C, 5 d, 39% yield). [H2bpy]3[SiMnW11O39]·1.25H2O crystallizes in the monoclinic space group P21/n with Z = 4 (single crystal XRD) and exhibits a new zigzag chain structure, which is different to the straight chain structure reported for one-dimensional transition metal substituted Keggin heteropolytungstates. Furthermore, the zigzag chains of the title compound form layers which are stacked parallel giving a three-dimensional structure with dumbbell-like one-dimensional channels. -(MENG, J. X.; MA, Y.; XU, X. X.; LI, Y. G.; WANG*, E. B.; Chin.