The black, air and moisture sensitive octastannanediide R* 6Sn8[Na(THF)2]2 (4) (R* = SitBu3) is prepared by reaction of Sn[N(SiMe3)2]2 with R*Na in tBuOMe at -78°C. Red brown octastannane R*6Sn8 (5) is formed by thermolysis of the tristannacyclopropene R*4Sn3 in benzene at 100 °C. According to the result of the X-ray structural analysis, 4 contains a Sn8 cubane with six Sn atoms each connected with R* and two at the end of a space diagonal connected with Na(THF)2. A preliminary X-ray structure analysis shows 5 to adopt the same Sn8 cubane structure as 4 with two bare Sn atoms at the end of a space diagonal.