A novel Ru-contg. silicotungstate of [Me2NH2]8K2H2[(ホウ-SiW10O36)2Ru4Cl4O2(OH)4]窶「23H2O (1) was obtained as a single crystal suitable for x-ray crystallog. anal. by the reaction of a divacant lacunary ホウ-Keggin silicotungstate K8[ホウ-SiW10O36] with K2[RuCl5(OH2)]. The unprecedented dimeric silicotungstate consisted of two [ホウ-SiW10O36]8- units sandwiching an adamantanoid Ru-O cluster core [Ru4Cl4O2(OH)4]4+. [on SciFinder(R)]